Added in API level 34
Also in T Extensions 7

Summary: Nested Classes | Constants | Inherited Constants | Fields | Methods | Inherited Methods

JoinSpec

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Kotlin |Java

public final class JoinSpec
extends Object implements Parcelable

java.lang.Object
↳	android.app.appsearch.JoinSpec

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This class represents the specifications for the joining operation in search.

Joins are only possible for matching on the qualified id of an outer document and a property value within a subquery document. In the subquery documents, these values may be referred to with a property path such as "email.recipient.id" or "entityId" or a property expression. One such property expression is "this.qualifiedId()", which refers to the document's combined package, database, namespace, and id.

Note that in order for perform the join, the property referred to by getChildPropertyExpression() has to be a property with AppSearchSchema.StringPropertyConfig.getJoinableValueType() set to AppSearchSchema.StringPropertyConfig.JOINABLE_VALUE_TYPE_QUALIFIED_ID. Otherwise no documents will be joined to any SearchResult.

Take these outer query and subquery results for example:

Outer result {
   id: id1
   score: 5
 }
 Subquery result 1 {
   id: id2
   score: 2
   entityId: pkg$db/ns#id1
   notes: This is some doc
 }
 Subquery result 2 {
   id: id3
   score: 3
   entityId: pkg$db/ns#id2
   notes: This is another doc
 }
 

In this example, subquery result 1 contains a property "entityId" whose value is "pkg$db/ns#id1", referring to the outer result. If you call Builder with "entityId", we will retrieve the value of the property "entityId" from the child document, which is "pkg$db#ns/id1". Let's say the qualified id of the outer result is "pkg$db#ns/id1". This would mean the subquery result 1 document will be matched to that parent document. This is done by adding a SearchResult containing the child document to the top-level parent SearchResult.getJoinedResults().

If getChildPropertyExpression() is "notes", we will check the values of the notes property in the subquery results. In subquery result 1, this values is "This is some doc", which does not equal the qualified id of the outer query result. As such, subquery result 1 will not be joined to the outer query result.

It's possible to define an advanced ranking strategy in the nested SearchSpec and also use SearchSpec.RANKING_STRATEGY_JOIN_AGGREGATE_SCORE in the outer SearchSpec. In this case, the parents will be ranked based on an aggregation, such as the sum, of the signals calculated by scoring the joined documents with the advanced ranking strategy.

In terms of scoring, if SearchSpec.RANKING_STRATEGY_JOIN_AGGREGATE_SCORE is set in SearchSpec.getRankingStrategy, the scores of the outer SearchResults can be influenced by the ranking signals of the subquery results. For example, if the getAggregationScoringStrategy() is set to:

• JoinSpec.AGGREGATION_SCORING_MIN_RANKING_SIGNAL, the ranking signal of the outer SearchResult will be set to the minimum of the ranking signals of the subquery results. In this case, it will be the minimum of 2 and 3, which is 2.
• JoinSpec.AGGREGATION_SCORING_MAX_RANKING_SIGNAL, the ranking signal of the outer SearchResult will be 3.
• JoinSpec.AGGREGATION_SCORING_AVG_RANKING_SIGNAL, the ranking signal of the outer SearchResult will be 2.5.
• JoinSpec.AGGREGATION_SCORING_RESULT_COUNT, the ranking signal of the outer SearchResult will be 2 as there are two joined results.
• JoinSpec.AGGREGATION_SCORING_SUM_RANKING_SIGNAL, the ranking signal of the outer SearchResult will be 5, the sum of 2 and 3.
• JoinSpec.AGGREGATION_SCORING_OUTER_RESULT_RANKING_SIGNAL, the ranking signal of the outer SearchResult will stay as it is.

Referring to "this.childrenRankingSignals()" in the ranking signal of the outer query will return the signals calculated by scoring the joined documents using the scoring strategy in the nested SearchSpec, as in SearchResult.getRankingSignal.

Summary

Nested classes
class	JoinSpec.Builder Builder for objects.

Constants
int	AGGREGATION_SCORING_AVG_RANKING_SIGNAL Score the aggregation of joined documents using the average ranking signal.
int	AGGREGATION_SCORING_MAX_RANKING_SIGNAL Score the aggregation of joined documents using the largest ranking signal.
int	AGGREGATION_SCORING_MIN_RANKING_SIGNAL Score the aggregation of joined documents using the smallest ranking signal.
int	AGGREGATION_SCORING_OUTER_RESULT_RANKING_SIGNAL Do not score the aggregation of joined documents.
int	AGGREGATION_SCORING_RESULT_COUNT Score the aggregation of joined documents by counting the number of results.
int	AGGREGATION_SCORING_SUM_RANKING_SIGNAL Score the aggregation of joined documents using the sum of ranking signal.

Inherited constants

From interface android.os.Parcelable int CONTENTS_FILE_DESCRIPTOR Descriptor bit used with describeContents(): indicates that the Parcelable object's flattened representation includes a file descriptor. int PARCELABLE_WRITE_RETURN_VALUE Flag for use with writeToParcel(Parcel, int): the object being written is a return value, that is the result of a function such as "Parcelable someFunction()", "void someFunction(out Parcelable)", or "void someFunction(inout Parcelable)".

Fields
public static final Creator<JoinSpec>	CREATOR Creator class for JoinSpec.

Public methods
int	getAggregationScoringStrategy() Gets the joined document list scoring strategy.
String	getChildPropertyExpression() The property expression that is used to get values from child documents, returned from the nested search.
int	getMaxJoinedResultCount() Returns the max amount of SearchResult objects to return with the parent document, with a default of 10 SearchResults.
String	getNestedQuery() Returns the query to run on the joined documents.
SearchSpec	getNestedSearchSpec() Returns the search spec used to retrieve the joined documents.
void	writeToParcel(Parcel dest, int flags) Flatten this object in to a Parcel.

Inherited methods
From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait(long timeoutMillis, int nanos) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait(long timeoutMillis) Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed. final void wait() Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
From interface android.os.Parcelable abstract int describeContents() Describe the kinds of special objects contained in this Parcelable instance's marshaled representation. abstract void writeToParcel(Parcel dest, int flags) Flatten this object in to a Parcel.

Constants

AGGREGATION_SCORING_AVG_RANKING_SIGNAL

Added in API level 34
Also in T Extensions 7

public static final int AGGREGATION_SCORING_AVG_RANKING_SIGNAL

Score the aggregation of joined documents using the average ranking signal.

Constant Value: 3 (0x00000003)

AGGREGATION_SCORING_MAX_RANKING_SIGNAL

Added in API level 34
Also in T Extensions 7

public static final int AGGREGATION_SCORING_MAX_RANKING_SIGNAL

Score the aggregation of joined documents using the largest ranking signal.

Constant Value: 4 (0x00000004)

AGGREGATION_SCORING_MIN_RANKING_SIGNAL

Added in API level 34
Also in T Extensions 7

public static final int AGGREGATION_SCORING_MIN_RANKING_SIGNAL

Score the aggregation of joined documents using the smallest ranking signal.

Constant Value: 2 (0x00000002)

AGGREGATION_SCORING_OUTER_RESULT_RANKING_SIGNAL

Added in API level 34
Also in T Extensions 7

public static final int AGGREGATION_SCORING_OUTER_RESULT_RANKING_SIGNAL

Do not score the aggregation of joined documents. This is for the case where we want to perform a join, but keep the parent ranking signal.

Constant Value: 0 (0x00000000)

AGGREGATION_SCORING_RESULT_COUNT

Added in API level 34
Also in T Extensions 7

public static final int AGGREGATION_SCORING_RESULT_COUNT

Score the aggregation of joined documents by counting the number of results.

Constant Value: 1 (0x00000001)

AGGREGATION_SCORING_SUM_RANKING_SIGNAL

Added in API level 34
Also in T Extensions 7

public static final int AGGREGATION_SCORING_SUM_RANKING_SIGNAL

Score the aggregation of joined documents using the sum of ranking signal.

Constant Value: 5 (0x00000005)

Fields

CREATOR

Added in API level 35
Also in T Extensions 13

public static final Creator<JoinSpec> CREATOR

Creator class for JoinSpec.

Public methods

getAggregationScoringStrategy

Added in API level 34
Also in T Extensions 7

public int getAggregationScoringStrategy ()

Gets the joined document list scoring strategy.

The default scoring strategy is AGGREGATION_SCORING_OUTER_RESULT_RANKING_SIGNAL, which specifies that the score of the outer parent document will be used.

Returns
int	Value is AGGREGATION_SCORING_OUTER_RESULT_RANKING_SIGNAL, AGGREGATION_SCORING_RESULT_COUNT, AGGREGATION_SCORING_MIN_RANKING_SIGNAL, AGGREGATION_SCORING_AVG_RANKING_SIGNAL, AGGREGATION_SCORING_MAX_RANKING_SIGNAL, or AGGREGATION_SCORING_SUM_RANKING_SIGNAL

See also:

• SearchSpec.RANKING_STRATEGY_JOIN_AGGREGATE_SCORE

getChildPropertyExpression

Added in API level 34
Also in T Extensions 7

public String getChildPropertyExpression ()

The property expression that is used to get values from child documents, returned from the nested search. These values are then used to match them to parent documents. These are analogous to foreign keys.

Returns
String	the property expression to match in the child documents. This value cannot be null.

See also:

• JoinSpec.Builder

getMaxJoinedResultCount

Added in API level 34
Also in T Extensions 7

public int getMaxJoinedResultCount ()

Returns the max amount of SearchResult objects to return with the parent document, with a default of 10 SearchResults.

Returns
int

getNestedQuery

Added in API level 34
Also in T Extensions 7

public String getNestedQuery ()

Returns the query to run on the joined documents.

Returns
String	This value cannot be null.

getNestedSearchSpec

Added in API level 34
Also in T Extensions 7

public SearchSpec getNestedSearchSpec ()

Returns the search spec used to retrieve the joined documents.

If Builder.setNestedSearch is never called, this will return a SearchSpec with all default values. This will match every document, as the nested search query will be "" and no schema will be filtered out.

Returns
SearchSpec	This value cannot be null.

writeToParcel

Added in API level 34

public void writeToParcel (Parcel dest, 
                int flags)

Flatten this object in to a Parcel.

Parameters
dest	Parcel: This value cannot be null.
flags	int: Additional flags about how the object should be written. May be 0 or Parcelable.PARCELABLE_WRITE_RETURN_VALUE. Value is either 0 or a combination of Parcelable.PARCELABLE_WRITE_RETURN_VALUE, and android.os.Parcelable.PARCELABLE_ELIDE_DUPLICATES