com.squareup.sqlbrite

Class QueryObservable

java.lang.Object

<any>

com.squareup.sqlbrite.QueryObservable

public final class QueryObservable
extends <any>

An Observable of SqlBrite.Query which offers query-specific convenience operators.

Method Summary

Modifier and Type	Method and Description
<T> <any>	mapToList(<any> mapper) Given a function mapping the current row of a Cursor to T, transform each emitted SqlBrite.Query to a List<T>.
<T> <any>	mapToOne(<any> mapper) Given a function mapping the current row of a Cursor to T, transform each emitted SqlBrite.Query which returns a single row to T.
<T> <any>	mapToOneOrDefault(<any> mapper, T defaultValue) Given a function mapping the current row of a Cursor to T, transform each emitted SqlBrite.Query which returns a single row to T.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

mapToOne

public final <T> <any> mapToOne(<any> mapper)

Given a function mapping the current row of a Cursor to T, transform each emitted SqlBrite.Query which returns a single row to T.

It is an error for a query to pass through this operator with more than 1 row in its result set. Use LIMIT 1 on the underlying SQL query to prevent this. Result sets with 0 rows do not emit an item.

This method is equivalent to:

 flatMap(q -> q.asRows(mapper).take(1))
 

and a convenience operator for:

 lift(Query.mapToOne(mapper))
 

Parameters:

mapper - Maps the current Cursor row to T. May not return null.

mapToOneOrDefault

public final <T> <any> mapToOneOrDefault(<any> mapper,
                                         T defaultValue)

Given a function mapping the current row of a Cursor to T, transform each emitted SqlBrite.Query which returns a single row to T.

It is an error for a query to pass through this operator with more than 1 row in its result set. Use LIMIT 1 on the underlying SQL query to prevent this. Result sets with 0 rows emit defaultValue.

This method is equivalent to:

 flatMap(q -> q.asRows(mapper).take(1).defaultIfEmpty(defaultValue))
 

and a convenience operator for:

 lift(Query.mapToOneOrDefault(mapper, defaultValue))
 

Parameters:

mapper - Maps the current Cursor row to T. May not return null.

defaultValue - Value returned if result set is empty

mapToList

public final <T> <any> mapToList(<any> mapper)

Given a function mapping the current row of a Cursor to T, transform each emitted SqlBrite.Query to a List<T>.

Be careful using this operator as it will always consume the entire cursor and create objects for each row, every time this observable emits a new query. On tables whose queries update frequently or very large result sets this can result in the creation of many objects.

This method is equivalent to:

 flatMap(q -> q.asRows(mapper).toList())
 

and a convenience operator for:

 lift(Query.mapToList(mapper))
 

Consider using SqlBrite.Query.asRows(<any>) if you need to limit or filter in memory.

Parameters:

mapper - Maps the current Cursor row to T. May not return null.