== MongoDB Component

*Available as of Camel version 2.10*

According to Wikipedia: "NoSQL is a movement promoting a loosely defined
class of non-relational data stores that break with a long history of
relational databases and ACID guarantees." NoSQL solutions have grown in
popularity in the last few years, and major extremely-used sites and
services such as Facebook, LinkedIn, Twitter, etc. are known to use them
extensively to achieve scalability and agility.

Basically, NoSQL solutions differ from traditional RDBMS (Relational
Database Management Systems) in that they don't use SQL as their query
language and generally don't offer ACID-like transactional behaviour nor
relational data. Instead, they are designed around the concept of
flexible data structures and schemas (meaning that the traditional
concept of a database table with a fixed schema is dropped), extreme
scalability on commodity hardware and blazing-fast processing.

MongoDB is a very popular NoSQL solution and the camel-mongodb component
integrates Camel with MongoDB allowing you to interact with MongoDB
collections both as a producer (performing operations on the collection)
and as a consumer (consuming documents from a MongoDB collection).

MongoDB revolves around the concepts of documents (not as is office
documents, but rather hierarchical data defined in JSON/BSON) and
collections. This component page will assume you are familiar with them.
Otherwise, visit http://www.mongodb.org/[http://www.mongodb.org/].

Maven users will need to add the following dependency to their `pom.xml`
for this component:

[source,xml]
------------------------------------------------------------
<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-mongodb</artifactId>
    <version>x.y.z</version>
    <!-- use the same version as your Camel core version -->
</dependency>
------------------------------------------------------------

### URI format

[source,java]
---------------------------------------------------------------------------------------------------------------
mongodb:connectionBean?database=databaseName&collection=collectionName&operation=operationName[&moreOptions...]
---------------------------------------------------------------------------------------------------------------

### MongoDB options


// component options: START
The MongoDB component has no options.
// component options: END






// endpoint options: START
The MongoDB endpoint is configured using URI syntax:

----
mongodb:connectionBean
----

with the following path and query parameters:

==== Path Parameters (1 parameters):

[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *connectionBean* | *Required* Name of com.mongodb.Mongo to use. |  | String
|===

==== Query Parameters (23 parameters):

[width="100%",cols="2,5,^1,2",options="header"]
|===
| Name | Description | Default | Type
| *collection* (common) | Sets the name of the MongoDB collection to bind to this endpoint |  | String
| *collectionIndex* (common) | Sets the collection index (JSON FORMAT : field1 : order1 field2 : order2) |  | String
| *createCollection* (common) | Create collection during initialisation if it doesn't exist. Default is true. | true | boolean
| *database* (common) | Sets the name of the MongoDB database to target |  | String
| *operation* (common) | Sets the operation this endpoint will execute against MongoDB. For possible values see MongoDbOperation. |  | MongoDbOperation
| *outputType* (common) | Convert the output of the producer to the selected type : DBObjectList DBObject or DBCursor. DBObjectList or DBObject applies to findAll. DBCursor applies to all other operations. |  | MongoDbOutputType
| *writeConcern* (common) | Set the WriteConcern for write operations on MongoDB using the standard ones. Resolved from the fields of the WriteConcern class by calling the link WriteConcernvalueOf(String) method. | ACKNOWLEDGED | WriteConcern
| *bridgeErrorHandler* (consumer) | Allows for bridging the consumer to the Camel routing Error Handler which mean any exceptions occurred while the consumer is trying to pickup incoming messages or the likes will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions that will be logged at WARN or ERROR level and ignored. | false | boolean
| *exceptionHandler* (consumer) | To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this options is not in use. By default the consumer will deal with exceptions that will be logged at WARN or ERROR level and ignored. |  | ExceptionHandler
| *exchangePattern* (consumer) | Sets the exchange pattern when the consumer creates an exchange. |  | ExchangePattern
| *cursorRegenerationDelay* (advanced) | MongoDB tailable cursors will block until new data arrives. If no new data is inserted after some time the cursor will be automatically freed and closed by the MongoDB server. The client is expected to regenerate the cursor if needed. This value specifies the time to wait before attempting to fetch a new cursor and if the attempt fails how long before the next attempt is made. Default value is 1000ms. | 1000 | long
| *dynamicity* (advanced) | Sets whether this endpoint will attempt to dynamically resolve the target database and collection from the incoming Exchange properties. Can be used to override at runtime the database and collection specified on the otherwise static endpoint URI. It is disabled by default to boost performance. Enabling it will take a minimal performance hit. | false | boolean
| *readPreference* (advanced) | Sets a MongoDB ReadPreference on the Mongo connection. Read preferences set directly on the connection will be overridden by this setting. The link ReadPreferencevalueOf(String) utility method is used to resolve the passed readPreference value. Some examples for the possible values are nearest primary or secondary etc. |  | ReadPreference
| *synchronous* (advanced) | Sets whether synchronous processing should be strictly used or Camel is allowed to use asynchronous processing (if supported). | false | boolean
| *writeResultAsHeader* (advanced) | In write operations it determines whether instead of returning WriteResult as the body of the OUT message we transfer the IN message to the OUT and attach the WriteResult as a header. | false | boolean
| *persistentId* (tail) | One tail tracking collection can host many trackers for several tailable consumers. To keep them separate each tracker should have its own unique persistentId. |  | String
| *persistentTailTracking* (tail) | Enable persistent tail tracking which is a mechanism to keep track of the last consumed message across system restarts. The next time the system is up the endpoint will recover the cursor from the point where it last stopped slurping records. | false | boolean
| *persistRecords* (tail) | Sets the number of tailed records after which the tail tracking data is persisted to MongoDB. | -1 | int
| *tailTrackCollection* (tail) | Collection where tail tracking information will be persisted. If not specified link MongoDbTailTrackingConfigDEFAULT_COLLECTION will be used by default. |  | String
| *tailTrackDb* (tail) | Indicates what database the tail tracking mechanism will persist to. If not specified the current database will be picked by default. Dynamicity will not be taken into account even if enabled i.e. the tail tracking database will not vary past endpoint initialisation. |  | String
| *tailTrackField* (tail) | Field where the last tracked value will be placed. If not specified link MongoDbTailTrackingConfigDEFAULT_FIELD will be used by default. |  | String
| *tailTrackIncreasingField* (tail) | Correlation field in the incoming record which is of increasing nature and will be used to position the tailing cursor every time it is generated. The cursor will be (re)created with a query of type: tailTrackIncreasingField lastValue (possibly recovered from persistent tail tracking). Can be of type Integer Date String etc. NOTE: No support for dot notation at the current time so the field should be at the top level of the document. |  | String
| *tailTrackingStrategy* (tail) | Sets the strategy used to extract the increasing field value and to create the query to position the tail cursor. | LITERAL | MongoDBTailTracking Enum
|===
// endpoint options: END






### Configuration of database in Spring XML

The following Spring XML creates a bean defining the connection to a
MongoDB instance.

[source,xml]
----------------------------------------------------------------------------------------------------------------------------------
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    <bean id="mongoBean" class="com.mongodb.Mongo">
        <constructor-arg name="host" value="${mongodb.host}" />
        <constructor-arg name="port" value="${mongodb.port}" />
    </bean>
</beans>
----------------------------------------------------------------------------------------------------------------------------------

### Sample route

The following route defined in Spring XML executes the operation
link:mongodb.html[*dbStats*] on a collection.

*Get DB stats for specified collection*

[source,xml]
---------------------------------------------------------------------------------------------------------------------------
<route>
  <from uri="direct:start" />
  <!-- using bean 'mongoBean' defined above -->
  <to uri="mongodb:mongoBean?database=${mongodb.database}&amp;collection=${mongodb.collection}&amp;operation=getDbStats" />
  <to uri="direct:result" />
</route>
---------------------------------------------------------------------------------------------------------------------------

### MongoDB operations - producer endpoints

### Query operations

#### findById

This operation retrieves only one element from the collection whose _id
field matches the content of the IN message body. The incoming object
can be anything that has an equivalent to a BSON type. See
http://bsonspec.org/#/specification[http://bsonspec.org/#/specification]
and
http://www.mongodb.org/display/DOCS/Java+Types[http://www.mongodb.org/display/DOCS/Java+Types].

[source,java]
------------------------------------------------------------------------------
from("direct:findById")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=findById")
    .to("mock:resultFindById");
------------------------------------------------------------------------------


TIP: *Supports optional parameters*. This operation supports specifying a fields filter. See
link:mongodb.html[Specifying optional parameters].

#### findOneByQuery

Use this operation to retrieve just one element from the collection that
matches a MongoDB query. *The query object is extracted from the IN
message body*, i.e. it should be of type `DBObject` or convertible to
`DBObject`. It can be a JSON String or a Hashmap. See
link:mongodb.html[#Type conversions] for more info.

Example with no query (returns any object of the collection):

[source,java]
------------------------------------------------------------------------------------
from("direct:findOneByQuery")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=findOneByQuery")
    .to("mock:resultFindOneByQuery");
------------------------------------------------------------------------------------

Example with a query (returns one matching result):

[source,java]
------------------------------------------------------------------------------------
from("direct:findOneByQuery")
    .setBody().constant("{ \"name\": \"Raul Kripalani\" }")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=findOneByQuery")
    .to("mock:resultFindOneByQuery");
------------------------------------------------------------------------------------

TIP: *Supports optional parameters*. This operation supports specifying a fields filter and/or a sort clause. See
link:mongodb.html[Specifying optional parameters].

#### findAll

The `findAll` operation returns all documents matching a query, or none
at all, in which case all documents contained in the collection are
returned. *The query object is extracted from the IN message body*, i.e.
it should be of type `DBObject` or convertible to `DBObject`. It can be
a JSON String or a Hashmap. See link:mongodb.html[#Type conversions] for
more info.

Example with no query (returns all object in the collection):

[source,java]
-----------------------------------------------------------------------------
from("direct:findAll")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=findAll")
    .to("mock:resultFindAll");
-----------------------------------------------------------------------------

Example with a query (returns all matching results):

[source,java]
-----------------------------------------------------------------------------
from("direct:findAll")
    .setBody().constant("{ \"name\": \"Raul Kripalani\" }")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=findAll")
    .to("mock:resultFindAll");
-----------------------------------------------------------------------------

Paging and efficient retrieval is supported via the following headers:

[width="100%",cols="10%,10%,10%,70%",options="header",]
|=======================================================================
|Header key |Quick constant |Description (extracted from MongoDB API doc) |Expected type

|`CamelMongoDbNumToSkip` |`MongoDbConstants.NUM_TO_SKIP` |Discards a given number of elements at the beginning of the cursor. |int/Integer

|`CamelMongoDbLimit` |`MongoDbConstants.LIMIT` |Limits the number of elements returned. |int/Integer

|`CamelMongoDbBatchSize` |`MongoDbConstants.BATCH_SIZE` |Limits the number of elements returned in one batch. A cursor typically
fetches a batch of result objects and store them locally. If batchSize
is positive, it represents the size of each batch of objects retrieved.
It can be adjusted to optimize performance and limit data transfer. If
batchSize is negative, it will limit of number objects returned, that
fit within the max batch size limit (usually 4MB), and cursor will be
closed. For example if batchSize is -10, then the server will return a
maximum of 10 documents and as many as can fit in 4MB, then close the
cursor. Note that this feature is different from limit() in that
documents must fit within a maximum size, and it removes the need to
send a request to close the cursor server-side. The batch size can be
changed even after a cursor is iterated, in which case the setting will
apply on the next batch retrieval. |int/Integer
|=======================================================================

The `findAll` operation will also return the following OUT headers to
enable you to iterate through result pages if you are using paging:

[width="100%",cols="10%,10%,10%,70%",options="header",]
|=======================================================================
|Header key |Quick constant |Description (extracted from MongoDB API doc) |Data type

|`CamelMongoDbResultTotalSize` |`MongoDbConstants.RESULT_TOTAL_SIZE` |Number of objects matching the query. This does not take limit/skip into
consideration. |int/Integer

|`CamelMongoDbResultPageSize` |`MongoDbConstants.RESULT_PAGE_SIZE` |Number of objects matching the query. This does not take limit/skip into
consideration. |int/Integer
|=======================================================================

TIP: *Supports optional parameters*. This operation supports specifying a fields filter and/or a sort clause. See
link:mongodb.html[Specifying optional parameters].

#### count

Returns the total number of objects in a collection, returning a Long as
the OUT message body. +
The following example will count the number of records in the
"dynamicCollectionName" collection. Notice how dynamicity is enabled,
and as a result, the operation will not run against the
"notableScientists" collection, but against the "dynamicCollectionName"
collection.

[source,java]
------------------------------------------------------------------------------------------------------------------------------------
// from("direct:count").to("mongodb:myDb?database=tickets&collection=flights&operation=count&dynamicity=true");
Long result = template.requestBodyAndHeader("direct:count", "irrelevantBody", MongoDbConstants.COLLECTION, "dynamicCollectionName");
assertTrue("Result is not of type Long", result instanceof Long);
------------------------------------------------------------------------------------------------------------------------------------

From *Camel 2.14* onwards you can provide
a `com.mongodb.DBObject` object in the message body as a query, and
operation will return the amount of documents matching this criteria. 

 

[source,java]
------------------------------------------------------------------------------------------------------------------------
DBObject query = ...
Long count = template.requestBodyAndHeader("direct:count", query, MongoDbConstants.COLLECTION, "dynamicCollectionName");
------------------------------------------------------------------------------------------------------------------------

#### Specifying a fields filter (projection)

Query operations will, by default, return the matching objects in their
entirety (with all their fields). If your documents are large and you
only require retrieving a subset of their fields, you can specify a
field filter in all query operations, simply by setting the relevant
`DBObject` (or type convertible to `DBObject`, such as a JSON String,
Map, etc.) on the `CamelMongoDbFieldsFilter` header, constant shortcut:
`MongoDbConstants.FIELDS_FILTER`.

Here is an example that uses MongoDB's BasicDBObjectBuilder to simplify
the creation of DBObjects. It retrieves all fields except `_id` and
`boringField`:

[source,java]
----------------------------------------------------------------------------------------------------------------------------
// route: from("direct:findAll").to("mongodb:myDb?database=flights&collection=tickets&operation=findAll")
DBObject fieldFilter = BasicDBObjectBuilder.start().add("_id", 0).add("boringField", 0).get();
Object result = template.requestBodyAndHeader("direct:findAll", (Object) null, MongoDbConstants.FIELDS_FILTER, fieldFilter);
----------------------------------------------------------------------------------------------------------------------------

#### Specifying a sort clause

There is a often a requirement to fetch the min/max record from a 
collection based on sorting by a particular field. In Mongo the 
operation is performed using syntax similar to:

[source]
----------------------------------------------------------------------------------------------------------------------------
db.collection.find().sort({_id: -1}).limit(1)
// or
db.collection.findOne({$query:{},$orderby:{_id:-1}})
----------------------------------------------------------------------------------------------------------------------------

In a Camel route the SORT_BY header can be used with the findOneByQuery 
operation to achieve the same result. If the FIELDS_FILTER header is also
specified the operation will return a single field/value pair 
that can be passed directly to another component (for example, a 
parameterized MyBatis SELECT query). This example demonstrates fetching 
the temporally newest document from a collection and reducing the result 
to a single field, based on the `documentTimestamp` field:

[source,java]
----------------------------------------------------------------------------------------------------------------------------
.from("direct:someTriggeringEvent")
.setHeader(MongoDbConstants.SORT_BY).constant("{\"documentTimestamp\": -1}")
.setHeader(MongoDbConstants.FIELDS_FILTER).constant("{\"documentTimestamp\": 1}")
.setBody().constant("{}")
.to("mongodb:myDb?database=local&collection=myDemoCollection&operation=findOneByQuery")
.to("direct:aMyBatisParameterizedSelect")
;
----------------------------------------------------------------------------------------------------------------------------


### Create/update operations

#### insert

Inserts an new object into the MongoDB collection, taken from the IN
message body. Type conversion is attempted to turn it into `DBObject` or
a `List`. +
 Two modes are supported: single insert and multiple insert. For
multiple insert, the endpoint will expect a List, Array or Collections
of objects of any type, as long as they are - or can be converted to -
`DBObject`. All objects are inserted at once. The endpoint will
intelligently decide which backend operation to invoke (single or
multiple insert) depending on the input.

Example:

[source,java]
-----------------------------------------------------------------------------
from("direct:insert")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=insert");
-----------------------------------------------------------------------------

The operation will return a WriteResult, and depending on the
`WriteConcern` or the value of the `invokeGetLastError` option,
`getLastError()` would have been called already or not. If you want to
access the ultimate result of the write operation, you need to retrieve
the `CommandResult` by calling `getLastError()` or
`getCachedLastError()` on the `WriteResult`. Then you can verify the
result by calling `CommandResult.ok()`,
`CommandResult.getErrorMessage()` and/or `CommandResult.getException()`.

Note that the new object's `_id` must be unique in the collection. If
you don't specify the value, MongoDB will automatically generate one for
you. But if you do specify it and it is not unique, the insert operation
will fail (and for Camel to notice, you will need to enable
invokeGetLastError or set a WriteConcern that waits for the write
result).

This is not a limitation of the component, but it is how things work in
MongoDB for higher throughput. If you are using a custom `_id`, you are
expected to ensure at the application level that is unique (and this is
a good practice too).

Since Camel *2.15*: OID(s) of the inserted record(s) is stored in the
message header under `CamelMongoOid` key (`MongoDbConstants.OID`
constant). The value stored is `org.bson.types.ObjectId` for single
insert or `java.util.List<org.bson.types.ObjectId>` if multiple records
have been inserted.

#### save

The save operation is equivalent to an _upsert_ (UPdate, inSERT)
operation, where the record will be updated, and if it doesn't exist, it
will be inserted, all in one atomic operation. MongoDB will perform the
matching based on the _id field.

Beware that in case of an update, the object is replaced entirely and
the usage of
http://www.mongodb.org/display/DOCS/Updating#Updating-ModifierOperations[MongoDB's
$modifiers] is not permitted. Therefore, if you want to manipulate the
object if it already exists, you have two options:

1.  perform a query to retrieve the entire object first along with all
its fields (may not be efficient), alter it inside Camel and then save
it.
2.  use the update operation with
http://www.mongodb.org/display/DOCS/Updating#Updating-ModifierOperations[$modifiers],
which will execute the update at the server-side instead. You can enable
the upsert flag, in which case if an insert is required, MongoDB will
apply the $modifiers to the filter query object and insert the result.

For example:

[source,java]
---------------------------------------------------------------------------
from("direct:insert")
    .to("mongodb:myDb?database=flights&collection=tickets&operation=save");
---------------------------------------------------------------------------

#### update

Update one or multiple records on the collection. Requires a
List<DBObject> as the IN message body containing exactly 2 elements:

* Element 1 (index 0) => filter query => determines what objects will be
affected, same as a typical query object
* Element 2 (index 1) => update rules => how matched objects will be
updated. All
http://www.mongodb.org/display/DOCS/Updating#Updating-ModifierOperations[modifier
operations] from MongoDB are supported.

NOTE: *Multiupdates* . By default, MongoDB will only update 1 object even if multiple objects
match the filter query. To instruct MongoDB to update *all* matching
records, set the `CamelMongoDbMultiUpdate` IN message header to `true`.

A header with key `CamelMongoDbRecordsAffected` will be returned
(`MongoDbConstants.RECORDS_AFFECTED` constant) with the number of
records updated (copied from `WriteResult.getN()`).

Supports the following IN message headers:

[width="100%",cols="10%,10%,10%,70%",options="header",]
|=======================================================================
|Header key |Quick constant |Description (extracted from MongoDB API doc) |Expected type

|`CamelMongoDbMultiUpdate` |`MongoDbConstants.MULTIUPDATE` |If the update should be applied to all objects matching. See
http://www.mongodb.org/display/DOCS/Atomic+Operations[http://www.mongodb.org/display/DOCS/Atomic+Operations] |boolean/Boolean

|`CamelMongoDbUpsert` |`MongoDbConstants.UPSERT` |If the database should create the element if it does not exist |boolean/Boolean
|=======================================================================

For example, the following will update *all* records whose filterField
field equals true by setting the value of the "scientist" field to
"Darwin":

[source,java]
------------------------------------------------------------------------------------------------------------------------------------------
// route: from("direct:update").to("mongodb:myDb?database=science&collection=notableScientists&operation=update");
DBObject filterField = new BasicDBObject("filterField", true);
DBObject updateObj = new BasicDBObject("$set", new BasicDBObject("scientist", "Darwin"));
Object result = template.requestBodyAndHeader("direct:update", new Object[] {filterField, updateObj}, MongoDbConstants.MULTIUPDATE, true);
------------------------------------------------------------------------------------------------------------------------------------------

### Delete operations

#### remove

Remove matching records from the collection. The IN message body will
act as the removal filter query, and is expected to be of type
`DBObject` or a type convertible to it. +
 The following example will remove all objects whose field
'conditionField' equals true, in the science database, notableScientists
collection:

[source,java]
------------------------------------------------------------------------------------------------------------------
// route: from("direct:remove").to("mongodb:myDb?database=science&collection=notableScientists&operation=remove");
DBObject conditionField = new BasicDBObject("conditionField", true);
Object result = template.requestBody("direct:remove", conditionField);
------------------------------------------------------------------------------------------------------------------

A header with key `CamelMongoDbRecordsAffected` is returned
(`MongoDbConstants.RECORDS_AFFECTED` constant) with type `int`,
containing the number of records deleted (copied from
`WriteResult.getN()`).

### Other operations

#### aggregate

*Available as of Camel 2.14*

Perform a aggregation with the given pipeline contained in the
body. *Aggregations could be long and heavy operations. Use with care.*

 

[source,java]
----------------------------------------------------------------------------------------------------------------------------------------------------------------------
// route: from("direct:aggregate").to("mongodb:myDb?database=science&collection=notableScientists&operation=aggregate");
from("direct:aggregate")
    .setBody().constant("[{ $match : {$or : [{\"scientist\" : \"Darwin\"},{\"scientist\" : \"Einstein\"}]}},{ $group: { _id: \"$scientist\", count: { $sum: 1 }} } ]")
    .to("mongodb:myDb?database=science&collection=notableScientists&operation=aggregate")
    .to("mock:resultAggregate");
----------------------------------------------------------------------------------------------------------------------------------------------------------------------

#### getDbStats

Equivalent of running the `db.stats()` command in the MongoDB shell,
which displays useful statistic figures about the database. +
 For example:

[source,java]
-------------------------------------
> db.stats();
{
    "db" : "test",
    "collections" : 7,
    "objects" : 719,
    "avgObjSize" : 59.73296244784423,
    "dataSize" : 42948,
    "storageSize" : 1000058880,
    "numExtents" : 9,
    "indexes" : 4,
    "indexSize" : 32704,
    "fileSize" : 1275068416,
    "nsSizeMB" : 16,
    "ok" : 1
}
-------------------------------------

Usage example:

[source,java]
---------------------------------------------------------------------------------------------------------
// from("direct:getDbStats").to("mongodb:myDb?database=flights&collection=tickets&operation=getDbStats");
Object result = template.requestBody("direct:getDbStats", "irrelevantBody");
assertTrue("Result is not of type DBObject", result instanceof DBObject);
---------------------------------------------------------------------------------------------------------

The operation will return a data structure similar to the one displayed
in the shell, in the form of a `DBObject` in the OUT message body.

#### getColStats

Equivalent of running the `db.collection.stats()` command in the MongoDB
shell, which displays useful statistic figures about the collection. +
 For example:

[source,java]
-----------------------------
> db.camelTest.stats();
{
    "ns" : "test.camelTest",
    "count" : 100,
    "size" : 5792,
    "avgObjSize" : 57.92,
    "storageSize" : 20480,
    "numExtents" : 2,
    "nindexes" : 1,
    "lastExtentSize" : 16384,
    "paddingFactor" : 1,
    "flags" : 1,
    "totalIndexSize" : 8176,
    "indexSizes" : {
        "_id_" : 8176
    },
    "ok" : 1
}
-----------------------------

Usage example:

[source,java]
-----------------------------------------------------------------------------------------------------------
// from("direct:getColStats").to("mongodb:myDb?database=flights&collection=tickets&operation=getColStats");
Object result = template.requestBody("direct:getColStats", "irrelevantBody");
assertTrue("Result is not of type DBObject", result instanceof DBObject);
-----------------------------------------------------------------------------------------------------------

The operation will return a data structure similar to the one displayed
in the shell, in the form of a `DBObject` in the OUT message body.

#### command

*Available as of Camel 2.15*

Run the body as a command on database. Usefull for admin operation as
getting host informations, replication or sharding status.

Collection parameter is not use for this operation.

[source,java]
--------------------------------------------------------------------------------
// route: from("command").to("mongodb:myDb?database=science&operation=command");
DBObject commandBody = new BasicDBObject("hostInfo", "1");
Object result = template.requestBody("direct:command", commandBody);
--------------------------------------------------------------------------------

### Dynamic operations

An Exchange can override the endpoint's fixed operation by setting the
`CamelMongoDbOperation` header, defined by the
`MongoDbConstants.OPERATION_HEADER` constant. +
 The values supported are determined by the MongoDbOperation enumeration
and match the accepted values for the `operation` parameter on the
endpoint URI.

For example:

[source,java]
-----------------------------------------------------------------------------------------------------------------------------
// from("direct:insert").to("mongodb:myDb?database=flights&collection=tickets&operation=insert");
Object result = template.requestBodyAndHeader("direct:insert", "irrelevantBody", MongoDbConstants.OPERATION_HEADER, "count");
assertTrue("Result is not of type Long", result instanceof Long);
-----------------------------------------------------------------------------------------------------------------------------

### Tailable Cursor Consumer

MongoDB offers a mechanism to instantaneously consume ongoing data from
a collection, by keeping the cursor open just like the `tail -f` command
of *nix systems. This mechanism is significantly more efficient than a
scheduled poll, due to the fact that the server pushes new data to the
client as it becomes available, rather than making the client ping back
at scheduled intervals to fetch new data. It also reduces otherwise
redundant network traffic.

There is only one requisite to use tailable cursors: the collection must
be a "capped collection", meaning that it will only hold N objects, and
when the limit is reached, MongoDB flushes old objects in the same order
they were originally inserted. For more information, please refer to:
http://www.mongodb.org/display/DOCS/Tailable+Cursors[http://www.mongodb.org/display/DOCS/Tailable+Cursors].

The Camel MongoDB component implements a tailable cursor consumer,
making this feature available for you to use in your Camel routes. As
new objects are inserted, MongoDB will push them as DBObjects in natural
order to your tailable cursor consumer, who will transform them to an
Exchange and will trigger your route logic.

### How the tailable cursor consumer works

To turn a cursor into a tailable cursor, a few special flags are to be
signalled to MongoDB when first generating the cursor. Once created, the
cursor will then stay open and will block upon calling the
`DBCursor.next()` method until new data arrives. However, the MongoDB
server reserves itself the right to kill your cursor if new data doesn't
appear after an indeterminate period. If you are interested to continue
consuming new data, you have to regenerate the cursor. And to do so, you
will have to remember the position where you left off or else you will
start consuming from the top again.

The Camel MongoDB tailable cursor consumer takes care of all these tasks
for you. You will just need to provide the key to some field in your
data of increasing nature, which will act as a marker to position your
cursor every time it is regenerated, e.g. a timestamp, a sequential ID,
etc. It can be of any datatype supported by MongoDB. Date, Strings and
Integers are found to work well. We call this mechanism "tail tracking"
in the context of this component.

The consumer will remember the last value of this field and whenever the
cursor is to be regenerated, it will run the query with a filter like:
`increasingField > lastValue`, so that only unread data is consumed.

*Setting the increasing field:* Set the key of the increasing field on
the endpoint URI `tailTrackingIncreasingField` option. In Camel 2.10, it
must be a top-level field in your data, as nested navigation for this
field is not yet supported. That is, the "timestamp" field is okay, but
"nested.timestamp" will not work. Please open a ticket in the Camel JIRA
if you do require support for nested increasing fields.

*Cursor regeneration delay:* One thing to note is that if new data is
not already available upon initialisation, MongoDB will kill the cursor
instantly. Since we don't want to overwhelm the server in this case, a
`cursorRegenerationDelay` option has been introduced (with a default
value of 1000ms.), which you can modify to suit your needs.

An example:

[source,java]
-----------------------------------------------------------------------------------------------------
from("mongodb:myDb?database=flights&collection=cancellations&tailTrackIncreasingField=departureTime")
    .id("tailableCursorConsumer1")
    .autoStartup(false)
    .to("mock:test");
-----------------------------------------------------------------------------------------------------

The above route will consume from the "flights.cancellations" capped
collection, using "departureTime" as the increasing field, with a
default regeneration cursor delay of 1000ms.

### Persistent tail tracking

Standard tail tracking is volatile and the last value is only kept in
memory. However, in practice you will need to restart your Camel
container every now and then, but your last value would then be lost and
your tailable cursor consumer would start consuming from the top again,
very likely sending duplicate records into your route.

To overcome this situation, you can enable the *persistent tail
tracking* feature to keep track of the last consumed increasing value in
a special collection inside your MongoDB database too. When the consumer
initialises again, it will restore the last tracked value and continue
as if nothing happened.

The last read value is persisted on two occasions: every time the cursor
is regenerated and when the consumer shuts down. We may consider
persisting at regular intervals too in the future (flush every 5
seconds) for added robustness if the demand is there. To request this
feature, please open a ticket in the Camel JIRA.

### Enabling persistent tail tracking

To enable this function, set at least the following options on the
endpoint URI:

* `persistentTailTracking` option to `true`
* `persistentId` option to a unique identifier for this consumer, so
that the same collection can be reused across many consumers

Additionally, you can set the `tailTrackDb`, `tailTrackCollection` and
`tailTrackField` options to customise where the runtime information will
be stored. Refer to the endpoint options table at the top of this page
for descriptions of each option.

For example, the following route will consume from the
"flights.cancellations" capped collection, using "departureTime" as the
increasing field, with a default regeneration cursor delay of 1000ms,
with persistent tail tracking turned on, and persisting under the
"cancellationsTracker" id on the "flights.camelTailTracking", storing
the last processed value under the "lastTrackingValue" field
(`camelTailTracking` and `lastTrackingValue` are defaults).

[source,java]
-----------------------------------------------------------------------------------------------------------------------------------
from("mongodb:myDb?database=flights&collection=cancellations&tailTrackIncreasingField=departureTime&persistentTailTracking=true" + 
     "&persistentId=cancellationsTracker")
    .id("tailableCursorConsumer2")
    .autoStartup(false)
    .to("mock:test");
-----------------------------------------------------------------------------------------------------------------------------------

Below is another example identical to the one above, but where the
persistent tail tracking runtime information will be stored under the
"trackers.camelTrackers" collection, in the "lastProcessedDepartureTime"
field:

[source,java]
-----------------------------------------------------------------------------------------------------------------------------------
from("mongodb:myDb?database=flights&collection=cancellations&tailTrackIncreasingField=departureTime&persistentTailTracking=true" + 
     "&persistentId=cancellationsTracker&tailTrackDb=trackers&tailTrackCollection=camelTrackers" + 
     "&tailTrackField=lastProcessedDepartureTime")
    .id("tailableCursorConsumer3")
    .autoStartup(false)
    .to("mock:test");
-----------------------------------------------------------------------------------------------------------------------------------

### Oplog Tail Tracking

The *oplog* collection tracking feature allows to implement trigger like functionality in MongoDB.
In order to activate this collection you will have first to activate a replica set. For more
information on this topic please check https://docs.mongodb.com/manual/tutorial/deploy-replica-set/ .

Below you can find an example of a Java DSL based route demonstrating how you can use the component to track the *oplog*
collection. In this specific case we are filtering the events which affect a collection *customers* in
database *optlog_test*. Note that the `tailTrackIncreasingField` is a timestamp field ('ts') which implies
that you have to use the `tailTrackingStrategy` parameter with the *TIMESTAMP* value.

[source,java]
-----------------------------------------------------------------------------------------------------------------------------------
import com.mongodb.BasicDBObject;
import com.mongodb.MongoClient;
import org.apache.camel.Exchange;
import org.apache.camel.Message;
import org.apache.camel.Processor;
import org.apache.camel.builder.RouteBuilder;
import org.apache.camel.component.mongodb.MongoDBTailTrackingEnum;
import org.apache.camel.main.Main;

import java.io.InputStream;

/**
 * For this to work you need to turn on the replica set
 * <p>
 * Commands to create a replica set:
 * <p>
 * rs.initiate( {
 * _id : "rs0",
 * members: [ { _id : 0, host : "localhost:27017" } ]
 * })
 */
public class MongoDbTracker {

    private final String database;

    private final String collection;

    private final String increasingField;

    private MongoDBTailTrackingEnum trackingStrategy;

    private int persistRecords = -1;

    private boolean persistenTailTracking;

    public MongoDbTracker(String database, String collection, String increasingField) {
        this.database = database;
        this.collection = collection;
        this.increasingField = increasingField;
    }

    public static void main(String[] args) throws Exception {
        final MongoDbTracker mongoDbTracker = new MongoDbTracker("local", "oplog.rs", "ts");
        mongoDbTracker.setTrackingStrategy(MongoDBTailTrackingEnum.TIMESTAMP);
        mongoDbTracker.setPersistRecords(5);
        mongoDbTracker.setPersistenTailTracking(true);
        mongoDbTracker.startRouter();
        // run until you terminate the JVM
        System.out.println("Starting Camel. Use ctrl + c to terminate the JVM.\n");

    }

    public void setTrackingStrategy(MongoDBTailTrackingEnum trackingStrategy) {
        this.trackingStrategy = trackingStrategy;
    }

    public void setPersistRecords(int persistRecords) {
        this.persistRecords = persistRecords;
    }

    public void setPersistenTailTracking(boolean persistenTailTracking) {
        this.persistenTailTracking = persistenTailTracking;
    }

    void startRouter() throws Exception {
        // create a Main instance
        Main main = new Main();
        main.bind(MongoConstants.CONN_NAME, new MongoClient("localhost", 27017));
        main.addRouteBuilder(new RouteBuilder() {
            @Override
            public void configure() throws Exception {
                getContext().getTypeConverterRegistry().addTypeConverter(InputStream.class, BasicDBObject.class,
                        new MongoToInputStreamConverter());
                from("mongodb://" + MongoConstants.CONN_NAME + "?database=" + database
                        + "&collection=" + collection
                        + "&persistentTailTracking=" + persistenTailTracking
                        + "&persistentId=trackerName" + "&tailTrackDb=local"
                        + "&tailTrackCollection=talendTailTracking"
                        + "&tailTrackField=lastTrackingValue"
                        + "&tailTrackIncreasingField=" + increasingField
                        + "&tailTrackingStrategy=" + trackingStrategy.toString()
                        + "&persistRecords=" + persistRecords
                        + "&cursorRegenerationDelay=1000")
                        .filter().jsonpath("$[?(@.ns=='optlog_test.customers')]")
                        .id("logger")
                        .to("log:logger?level=WARN")
                        .process(new Processor() {
                            public void process(Exchange exchange) throws Exception {
                                Message message = exchange.getIn();
                                System.out.println(message.getBody().toString());
                                exchange.getOut().setBody(message.getBody().toString());
                            }
                        });
            }
        });
        main.run();
    }
}
-----------------------------------------------------------------------------------------------------------------------------------


### Type conversions

The `MongoDbBasicConverters` type converter included with the
camel-mongodb component provides the following conversions:

[width="100%",cols="10%,10%,10%,70%",options="header",]
|=======================================================================
|Name |From type |To type |How?

|fromMapToDBObject |`Map` |`DBObject` |constructs a new `BasicDBObject` via the `new BasicDBObject(Map m)`
constructor

|fromBasicDBObjectToMap |`BasicDBObject` |`Map` |`BasicDBObject` already implements `Map`

|fromStringToDBObject |`String` |`DBObject` |uses `com.mongodb.util.JSON.parse(String s)`

|fromAnyObjectToDBObject |`Object`  |`DBObject` |uses the http://jackson.codehaus.org/[Jackson library] to convert the
object to a `Map`, which is in turn used to initialise a new
`BasicDBObject`
|=======================================================================

This type converter is auto-discovered, so you don't need to configure
anything manually.

### See also

* http://www.mongodb.org/[MongoDB website]
* http://en.wikipedia.org/wiki/NoSQL[NoSQL Wikipedia article]
* http://api.mongodb.org/java/current/[MongoDB Java driver API docs -
current version]
*
http://svn.apache.org/viewvc/camel/trunk/components/camel-mongodb/src/test/[Unit
tests] for more examples of usage
