Builder

Builder

Builder(childPropertyExpression: String)

Create a specification for the joining operation in search.

The child property expression specifies how to join documents. Documents with a child property expression equal to the qualified id of the parent will be retrieved.

Property expressions differ from PropertyPath as property expressions may refer to document properties or nested document properties such as "person.business.id" as well as a property expression. Currently the only property expression is "this.qualifiedId()". PropertyPath objects may only reference document properties and nested document properties.

In order to join a child document to a parent document, the child document must contain the parent's qualified id at the property expression specified by this method.

build

fun build(): JoinSpec

Constructs a new JoinSpec from the contents of this builder.

setAggregationScoringStrategy

fun setAggregationScoringStrategy(aggregationScoringStrategy: Int): JoinSpec.Builder

Sets how we derive a single score from a list of joined documents.

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

setMaxJoinedResultCount

fun setMaxJoinedResultCount(maxJoinedResultCount: Int): JoinSpec.Builder

Sets the max amount of SearchResults to return with the parent document, with a default of 10 SearchResults.

This does NOT limit the number of results that are joined with the parent document for scoring. This means that, when set, only a maximum of maxJoinedResultCount results will be returned with each parent document, but all results that are joined with a parent will factor into the score.

setNestedSearch

fun setNestedSearch(
    nestedQuery: String, 
    nestedSearchSpec: SearchSpec
): JoinSpec.Builder

Sets the query and the SearchSpec for the documents being joined. This will score and rank the joined documents as well as filter the joined documents.

If SearchSpec.RANKING_STRATEGY_JOIN_AGGREGATE_SCORE is set in the outer SearchSpec, the resulting signals will be used to rank the parent documents. Note that the aggregation strategy also needs to be set with android.app.appsearch.JoinSpec.Builder#setAggregationScoringStrategy, otherwise the default will be android.app.appsearch.JoinSpec#AGGREGATION_SCORING_OUTER_RESULT_RANKING_SIGNAL, which will just use the parent documents ranking signal.

If this method is never called, JoinSpec.getNestedQuery will return an empty string, meaning we will join with every possible document that matches the equality constraints and hasn't been filtered out by the type or namespace filters.