org.apache.lucene.facet

## Class DrillDownQuery

- java.lang.Object
- - org.apache.lucene.search.Query
  - - org.apache.lucene.facet.DrillDownQuery

-     public final class DrillDownQuery
      extends Query

  A `Query` for drill-down over facet categories. You should call `add(String, String...)` for every group of categories you want to drill-down over.

  NOTE: if you choose to create your own `Query` by calling `term(java.lang.String, java.lang.String, java.lang.String...)`, it is recommended to wrap it in a `BoostQuery` with a boost of `0.0f`, so that it does not affect the scores of the documents.

  WARNING: This API is experimental and might change in incompatible ways in the next release.

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `DrillDownQuery(FacetsConfig config)` Creates a new `DrillDownQuery` without a base query, to perform a pure browsing query (equivalent to using `MatchAllDocsQuery` as base).
    `DrillDownQuery(FacetsConfig config, Query baseQuery)` Creates a new `DrillDownQuery` over the given base query.

  - ### Method Summary

    All Methods Static Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `add(String dim, Query subQuery)` Expert: add a custom drill-down subQuery.
    `void` | `add(String dim, String... path)` Adds one dimension of drill downs; if you pass the same dimension more than once it is OR'd with the previous constraints on that dimension, and all dimensions are AND'd against each other and the base query.
    `DrillDownQuery` | `clone()`
    `boolean` | `equals(Object other)`
    `int` | `hashCode()`
    `Query` | `rewrite(IndexReader r)`
    `static Term` | `term(String field, String dim, String... path)` Creates a drill-down term.
    `String` | `toString(String field)`
    `void` | `visit(QueryVisitor visitor)`

    - ### Methods inherited from class org.apache.lucene.search.Query

      `classHash, createWeight, sameClassAs, toString`

    - ### Methods inherited from class java.lang.Object

      `finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Constructor Detail

    - #### DrillDownQuery

          public DrillDownQuery(FacetsConfig config)

      Creates a new `DrillDownQuery` without a base query, to perform a pure browsing query (equivalent to using `MatchAllDocsQuery` as base).

    - #### DrillDownQuery

          public DrillDownQuery(FacetsConfig config,
                                Query baseQuery)

      Creates a new `DrillDownQuery` over the given base query. Can be `null`, in which case the result `Query` from `rewrite(IndexReader)` will be a pure browsing query, filtering on the added categories only.

  - ### Method Detail

    - #### term

          public static Term term(String field,
                                  String dim,
                                  String... path)

      Creates a drill-down term.

    - #### add

          public void add(String dim,
                          String... path)

      Adds one dimension of drill downs; if you pass the same dimension more than once it is OR'd with the previous constraints on that dimension, and all dimensions are AND'd against each other and the base query.

    - #### add

          public void add(String dim,
                          Query subQuery)

      Expert: add a custom drill-down subQuery. Use this when you have a separate way to drill-down on the dimension than the indexed facet ordinals.

    - #### clone

          public DrillDownQuery clone()

      Overrides:
        `clone` in class `Object`

    - #### hashCode

          public int hashCode()

      Specified by:
        `hashCode` in class `Query`

    - #### equals

          public boolean equals(Object other)

      Specified by:
        `equals` in class `Query`

    - #### rewrite

          public Query rewrite(IndexReader r)
                        throws IOException

      Overrides:
        `rewrite` in class `Query`
      Throws:
        `IOException`

    - #### toString

          public String toString(String field)

      Specified by:
        `toString` in class `Query`

    - #### visit

          public void visit(QueryVisitor visitor)

      Overrides:
        `visit` in class `Query`

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