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## org.apache.lucene.facet.search.params
Class FacetRequest

    java.lang.Object
      org.apache.lucene.facet.search.params.FacetRequest

All Implemented Interfaces:
  Cloneable

Direct Known Subclasses:
  AssociationFloatSumFacetRequest, AssociationIntSumFacetRequest, CountFacetRequest, ScoreFacetRequest

    public abstract class FacetRequest

extends Object
implements Cloneable

Request to accumulate facet information for a specified facet and possibly also some of its descendants, upto a specified depth.

The facet request additionally defines what information should be computed within the facet results, if and how should results be ordered, etc.

An example facet request is to look at all sub-categories of "Author", and return the 10 with the highest counts (sorted by decreasing count).

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

Nested Class Summary
`static class` | `FacetRequest.ResultMode` Result structure manner of applying request's limits such as `getNumLabel()` and `getNumResults()`.
`static class` | `FacetRequest.SortBy` Sort options for facet results.
`static class` | `FacetRequest.SortOrder` Requested sort order for the results.

Field Summary
`static int` | `DEFAULT_DEPTH` Default depth for facets accumulation.
`static FacetRequest.ResultMode` | `DEFAULT_RESULT_MODE` Default result mode
`static FacetRequest.SortBy` | `DEFAULT_SORT_BY` Default sort mode.

Constructor Summary
`FacetRequest(CategoryPath path, int numResults)` Initialize the request with a given path, and a requested number of facets results.

Method Summary
`Object` | `clone()`
`abstract Aggregator` | `createAggregator(boolean useComplements, FacetArrays arrays, IndexReader indexReader, TaxonomyReader taxonomy)` Create an aggregator for this facet request.
`CategoryListIterator` | `createCategoryListIterator(IndexReader reader, TaxonomyReader taxo, FacetSearchParams sParams, int partition)` Create the category list iterator for the specified partition.
`FacetResultsHandler` | `createFacetResultsHandler(TaxonomyReader taxonomyReader)` Creates a new `FacetResultsHandler` that matches the request logic and current settings, such as `depth`, `limits-mode`, etc, as well as the passed in `TaxonomyReader`.
`boolean` | `equals(Object o)`
`CategoryPath` | `getCategoryPath()` The root category of this facet request.
`int` | `getDepth()` How deeply to look under the given category.
`int` | `getNumLabel()` If getNumLabel()
`int` | `getNumResults()` The number of sub-categories to return (at most).
`FacetRequest.ResultMode` | `getResultMode()` Return the requested result mode.
`FacetRequest.SortBy` | `getSortBy()` Specify how should results be sorted.
`FacetRequest.SortOrder` | `getSortOrder()` Return the requested order of results.
`abstract double` | `getValueOf(FacetArrays arrays, int idx)` Return the value of a category used for facets computations for this request.
`int` | `hashCode()`
`abstract boolean` | `requireDocumentScore()` Indicates whether the results of this request depends on each result document's score
`void` | `setDepth(int depth)`
`void` | `setNumLabel(int numLabel)`
`void` | `setResultMode(FacetRequest.ResultMode resultMode)`
`void` | `setSortBy(FacetRequest.SortBy sortBy)`
`void` | `setSortOrder(FacetRequest.SortOrder sortOrder)`
`boolean` | `supportsComplements()` Indicates whether this facet request is eligible for applying the complements optimization.
`String` | `toString()`

Methods inherited from class java.lang.Object
`finalize, getClass, notify, notifyAll, wait, wait, wait`

Field Detail

### DEFAULT_DEPTH

    public static final int DEFAULT_DEPTH

  Default depth for facets accumulation.

  See Also:
    `getDepth()`, Constant Field Values

### DEFAULT_SORT_BY

    public static final FacetRequest.SortBy DEFAULT_SORT_BY

  Default sort mode.

  See Also:
    `getSortBy()`

### DEFAULT_RESULT_MODE

    public static final FacetRequest.ResultMode DEFAULT_RESULT_MODE

  Default result mode

  See Also:
    `getResultMode()`

Constructor Detail

### FacetRequest

    public FacetRequest(CategoryPath path,
                        int numResults)

  Initialize the request with a given path, and a requested number of facets results. By default, all returned results would be labeled - to alter this default see `setNumLabel(int)`.

  NOTE: if `numResults` is given as `Integer.MAX_VALUE` than all the facet results would be returned, without any limit.

  NOTE: it is assumed that the given `CategoryPath` is not modified after construction of this object. Otherwise, some things may not function properly, e.g. `hashCode()`.

  Throws:
    `IllegalArgumentException` - if numResults is ≤ 0

Method Detail

### clone

    public Object clone()
                 throws CloneNotSupportedException

  Overrides:
    `clone` in class `Object`
  Throws:
    `CloneNotSupportedException`

### setNumLabel

    public void setNumLabel(int numLabel)

### setDepth

    public void setDepth(int depth)

### setSortOrder

    public void setSortOrder(FacetRequest.SortOrder sortOrder)

### setSortBy

    public void setSortBy(FacetRequest.SortBy sortBy)

### getCategoryPath

    public final CategoryPath getCategoryPath()

  The root category of this facet request. The categories that are returned as a result of this request will all be descendants of this root.

  NOTE: you should not modify the returned `CategoryPath`, or otherwise some methonds may not work properly, e.g. `hashCode()`.

### getDepth

    public final int getDepth()

  How deeply to look under the given category. If the depth is 0, only the category itself is counted. If the depth is 1, its immediate children are also counted, and so on. If the depth is Integer.MAX_VALUE, all the category's descendants are counted.
  TODO (Facet): add AUTO_EXPAND option

### getNumLabel

    public final int getNumLabel()

  If getNumLabel() If Integer.MAX_VALUE is specified, all results are labled.

  The purpose of this parameter is to avoid having to run the whole faceted search again when the user asks for more values for the facet; The application can ask (getNumResults()) for more values than it needs to show, but keep getNumLabel() only the number it wants to immediately show. The slow-down caused by finding more values is negligible, because the slowest part - finding the categories' paths, is avoided.

  Depending on the `LimitsMode`, this limit is applied globally or per results node. In the global mode, if this limit is 3, only 3 top results would be labeled. In the per-node mode, if this limit is 3, 3 top children of `the target category` would be labeled, as well as 3 top children of each of them, and so forth, until the depth defined by `getDepth()`.

  See Also:
    `getResultMode()`

### getNumResults

    public final int getNumResults()

  The number of sub-categories to return (at most). If the sub-categories are returned.

  If Integer.MAX_VALUE is specified, all sub-categories are returned.

  Depending on the `LimitsMode`, this limit is applied globally or per results node. In the global mode, if this limit is 3, only 3 top results would be computed. In the per-node mode, if this limit is 3, 3 top children of `the target category` would be returned, as well as 3 top children of each of them, and so forth, until the depth defined by `getDepth()`.

  See Also:
    `getResultMode()`

### getSortBy

    public final FacetRequest.SortBy getSortBy()

  Specify how should results be sorted.

### getSortOrder

    public final FacetRequest.SortOrder getSortOrder()

  Return the requested order of results.

### toString

    public String toString()

  Overrides:
    `toString` in class `Object`

### createFacetResultsHandler

    public FacetResultsHandler createFacetResultsHandler(TaxonomyReader taxonomyReader)

  Creates a new `FacetResultsHandler` that matches the request logic and current settings, such as `depth`, `limits-mode`, etc, as well as the passed in `TaxonomyReader`.

  Parameters:
    `taxonomyReader` - taxonomy reader is needed e.g. for knowing the taxonomy size.

### getResultMode

    public final FacetRequest.ResultMode getResultMode()

  Return the requested result mode.

### setResultMode

    public void setResultMode(FacetRequest.ResultMode resultMode)

  Parameters:
    `resultMode` - the resultMode to set
  See Also:
    `getResultMode()`

### hashCode

    public int hashCode()

  Overrides:
    `hashCode` in class `Object`

### equals

    public boolean equals(Object o)

  Overrides:
    `equals` in class `Object`

### createAggregator

    public abstract Aggregator createAggregator(boolean useComplements,
                                                FacetArrays arrays,
                                                IndexReader indexReader,
                                                TaxonomyReader taxonomy)
                                         throws IOException

  Create an aggregator for this facet request. Aggregator action depends on request definition. For a count request, it will usually increment the count for that facet.

  Parameters:
    `useComplements` - whether the complements optimization is being used for current computation.
    `arrays` - provider for facet arrays in use for current computation.
    `indexReader` - index reader in effect.
    `taxonomy` - reader of taxonomy in effect.
  Throws:
    `IOException`

### createCategoryListIterator

    public CategoryListIterator createCategoryListIterator(IndexReader reader,
                                                           TaxonomyReader taxo,
                                                           FacetSearchParams sParams,
                                                           int partition)
                                                    throws IOException

  Create the category list iterator for the specified partition. If a non null cache is provided which contains the required data, use it for the iteration.

  Throws:
    `IOException`

### getValueOf

    public abstract double getValueOf(FacetArrays arrays,
                                      int idx)

  Return the value of a category used for facets computations for this request. For a count request this would be the count for that facet, i.e. an integer number. but for other requests this can be the result of a more complex operation, and the result can be any double precision number. Having this method with a general name value which is double precision allows to have more compact API and code for handling counts and perhaps other requests (such as for associations) very similarly, and by the same code and API, avoiding code duplication.

  Parameters:
    `arrays` - provider for facet arrays in use for current computation.
    `idx` - an index into the count arrays now in effect in `arrays`. E.g., for ordinal number n, with partition, of size partitionSize, now covering n, `getValueOf` would be invoked with `idx` being n % partitionSize.

### supportsComplements

    public boolean supportsComplements()

  Indicates whether this facet request is eligible for applying the complements optimization.

### requireDocumentScore

    public abstract boolean requireDocumentScore()

  Indicates whether the results of this request depends on each result document's score

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