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JoinSpec

public final class JoinSpec
extends Object

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

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 QUALIFIED_ID, which refers to the document's combined package, database, namespace, and id.

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.

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 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. If the getAggregationScoringStrategy() is set to AGGREGATION_SCORING_OUTER_RESULT_RANKING_SIGNAL, the ranking signal of the outer SearchResult will stay as it is.

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.

String QUALIFIED_ID

A property expression referring to the combined package name, database name, namespace, and id of the document.

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 that will be joined to 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.

Inherited methods

Constants

AGGREGATION_SCORING_AVG_RANKING_SIGNAL

Added in Android UpsideDownCake 
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 Android UpsideDownCake 
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 Android UpsideDownCake 
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 Android UpsideDownCake 
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 Android UpsideDownCake 
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 Android UpsideDownCake 
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)

QUALIFIED_ID

Added in Android UpsideDownCake 
public static final String QUALIFIED_ID

A property expression referring to the combined package name, database name, namespace, and id of the document.

For instance, if a document with an id of "id1" exists in the namespace "ns" within the database "db" created by package "pkg", this would evaluate to "pkg$db/ns#id1".

Constant Value: "this.qualifiedId()"

Public methods

getAggregationScoringStrategy

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

getChildPropertyExpression

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:

getMaxJoinedResultCount

public int getMaxJoinedResultCount ()

Returns the max amount of SearchResult objects that will be joined to the parent document, with a default of 10 SearchResults.

Returns
int

getNestedQuery

public String getNestedQuery ()

Returns the query to run on the joined documents.

Returns
String This value cannot be null.

getNestedSearchSpec

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.