Class ObjectSelect<T>
- All Implemented Interfaces:
Serializable
,ParameterizedQuery
,Query
,Select<T>
- Direct Known Subclasses:
PrefetchSelectQuery
For example, the following is a convenient way to return a record:
Artist a = ObjectSelect
.query(Artist.class)
.where(Artist.NAME.eq("Picasso"))
.selectOne(context);
- Since:
- 4.0
- See Also:
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Field Summary
Fields inherited from class org.apache.cayenne.query.FluentSelect
dbEntityName, distinct, entityName, entityType, having, havingExpressionIsActive, metaData, orderings, where
Fields inherited from class org.apache.cayenne.query.AbstractQuery
root
Fields inherited from class org.apache.cayenne.query.CacheableQuery
logger
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescription<E> ColumnSelect
<E> aggregate
(BaseProperty<E> property, String function, Class<E> type) Select result of some function, that aggregates values.<E extends Number>
ColumnSelect<E> avg
(NumericProperty<E> property) Select average value of property<E> ColumnSelect
<E> Select one specific property.static ColumnSelect
<Object[]> columnQuery
(Class<?> entityType, Property<?>... columns) Creates a ColumnSelect that will fetch multiple columns of a givenObjEntity
static <E> ColumnSelect
<E> columnQuery
(Class<?> entityType, Property<E> column) Creates a ColumnSelect that will fetch single property that can be resolved against a givenObjEntity
class.Select only specific properties.count()
Select COUNT(*)count
(BaseProperty<?> property) Select COUNT(property)protected org.apache.cayenne.query.ObjectSelectMetadata
createQuery
(Map<String, ?> parameters) This method is intended for internal use in aMappedSelect
.static ObjectSelect
<DataRow> dataRowQuery
(Class<?> entityType) Creates a ObjectSelect that fetches data for anObjEntity
determined from a provided class.static ObjectSelect
<DataRow> dataRowQuery
(Class<?> entityType, Expression expression) Creates a ObjectSelect that fetches data for anObjEntity
determined from a provided class and uses provided expression for its qualifier.static ObjectSelect
<DataRow> Creates a ObjectSelect that fetches DataRows for aDbEntity
determined from provided "dbEntityName".static ObjectSelect
<DataRow> dbQuery
(String dbEntityName, Expression expression) Creates a ObjectSelect that fetches DataRows for aDbEntity
determined from provided "dbEntityName" and uses provided expression for its qualifier.distinct()
Forces query to fetch DataRows.protected org.apache.cayenne.query.ObjectSelectMetadata
getMetaData
(EntityResolver resolver) Returns default select parameters.Appends a having qualifier expression of this query, using provided expression String and an array of position parameters.having
(Expression expression) Appends a having qualifier expression of this query.<E> ColumnSelect
<E> max
(ComparableProperty<E> property) Select maximum value of property<E extends Number>
ColumnSelect<E> max
(NumericProperty<E> property) Select maximum value of property<E> ColumnSelect
<E> min
(ComparableProperty<E> property) Select minimum value of property<E extends Number>
ColumnSelect<E> min
(NumericProperty<E> property) Select minimum value of propertystatic <T> ObjectSelect
<T> Creates a ObjectSelect that selects objects of a given persistent class.static <T> ObjectSelect
<T> Creates a ObjectSelect that fetches data forObjEntity
determined from provided "entityName", but fetches the result of a provided type.static <T> ObjectSelect
<T> query
(Class<T> entityType, Expression expression) Creates a ObjectSelect that selects objects of a given persistent class and uses provided expression for its qualifier.static <T> ObjectSelect
<T> query
(Class<T> entityType, Expression expression, List<Ordering> orderings) Creates a ObjectSelect that selects objects of a given persistent class and uses provided expression for its qualifier.long
selectCount
(ObjectContext context) Quick way to select count of recordsselectFirst
(ObjectContext context) Selects a single object using provided context.<E extends Number>
ColumnSelect<E> sum
(NumericProperty<E> property) Select sum of valuesMethods inherited from class org.apache.cayenne.query.FluentSelect
and, and, batchIterator, cacheGroup, cacheStrategy, cacheStrategy, castSelf, createSQLAction, dbEntityName, entityName, entityType, getActiveExpression, getColumns, getDbEntityName, getEntityName, getEntityType, getHaving, getLimit, getOffset, getOrderings, getPageSize, getPrefetches, getQueryTimeout, getStatementFetchSize, getWhere, initWithProperties, isDistinct, isFetchingDataRows, iterate, iterator, joinExpression, limit, localCache, localCache, offset, or, or, orderBy, orderBy, orderBy, orderBy, pageSize, prefetch, prefetch, queryTimeout, resolveRoot, route, routePrefetches, select, selectOne, setActiveExpression, sharedCache, sharedCache, statementFetchSize, where, where
Methods inherited from class org.apache.cayenne.query.AbstractQuery
getRoot, setRoot, toString
Methods inherited from class org.apache.cayenne.query.CacheableQuery
getCacheGroup, getCacheStrategy, setCacheGroup, setCacheStrategy, useLocalCache, useLocalCache, useSharedCache, useSharedCache
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface org.apache.cayenne.query.Query
createSQLAction, route
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Constructor Details
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ObjectSelect
protected ObjectSelect()
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Method Details
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query
Creates a ObjectSelect that selects objects of a given persistent class. -
query
Creates a ObjectSelect that selects objects of a given persistent class and uses provided expression for its qualifier. -
query
public static <T> ObjectSelect<T> query(Class<T> entityType, Expression expression, List<Ordering> orderings) Creates a ObjectSelect that selects objects of a given persistent class and uses provided expression for its qualifier. -
dataRowQuery
Creates a ObjectSelect that fetches data for anObjEntity
determined from a provided class. -
dataRowQuery
Creates a ObjectSelect that fetches data for anObjEntity
determined from a provided class and uses provided expression for its qualifier. -
query
Creates a ObjectSelect that fetches data forObjEntity
determined from provided "entityName", but fetches the result of a provided type. This factory method is most often used with generic classes that by themselves are not enough to resolve the entity to fetch. -
dbQuery
Creates a ObjectSelect that fetches DataRows for aDbEntity
determined from provided "dbEntityName". -
dbQuery
Creates a ObjectSelect that fetches DataRows for aDbEntity
determined from provided "dbEntityName" and uses provided expression for its qualifier.- Returns:
- this object
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columnQuery
Creates a ColumnSelect that will fetch single property that can be resolved against a givenObjEntity
class.- Parameters:
entityType
- base persistent class that will be used as a root for this querycolumn
- single column to select
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columnQuery
Creates a ColumnSelect that will fetch multiple columns of a givenObjEntity
- Parameters:
entityType
- base persistent class that will be used as a root for this querycolumns
- columns to select
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createMetadata
protected org.apache.cayenne.query.ObjectSelectMetadata createMetadata()- Specified by:
createMetadata
in classFluentSelect<T,
ObjectSelect<T>>
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having
Appends a having qualifier expression of this query. An equivalent toFluentSelect.and(Expression...)
that can be used a syntactic sugar.- Returns:
- this object
- Since:
- 4.2
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having
Appends a having qualifier expression of this query, using provided expression String and an array of position parameters. This is an equivalent to calling "and".- Returns:
- this object
- Since:
- 4.2
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fetchDataRows
Forces query to fetch DataRows. This automatically changes whatever result type was set previously to "DataRow".- Returns:
- this object
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columns
Select only specific properties.
Can be any properties that can be resolved against root entity type (root entity's properties, function call expressions, properties of relationships, etc).
List<Object[]> columns = ObjectSelect.query(Artist.class) .columns(Artist.ARTIST_NAME, Artist.DATE_OF_BIRTH) .select(context);
- Parameters:
properties
- array of properties to select- See Also:
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column
Select one specific property.
Can be any property that can be resolved against root entity type (root entity's property, function call expression, property of relationships, etc)
If you need several columns use
columns(Property[])
method.List<String> names = ObjectSelect.query(Artist.class) .column(Artist.ARTIST_NAME) .select(context);
- Parameters:
property
- single property to select- See Also:
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count
Select COUNT(*)- See Also:
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count
Select COUNT(property)
Can return different result than COUNT(*) as it will count only non null values
- See Also:
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min
Select minimum value of property
- See Also:
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min
Select minimum value of property
- See Also:
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max
Select maximum value of property
- See Also:
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max
Select maximum value of property
- See Also:
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avg
Select average value of property
- See Also:
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sum
Select sum of values
- See Also:
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aggregate
Select result of some function, that aggregates values.
- Since:
- 5.0
- See Also:
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distinct
- Returns:
- this
- Since:
- 4.2
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selectCount
Quick way to select count of records
Usage:
long count = ObjectSelect.query(Artist.class) .where(Artist.ARTIST_NAME.like("a%")) .selectCount(context);
- Parameters:
context
- to perform query- Returns:
- count of rows
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selectFirst
Description copied from interface:Select
Selects a single object using provided context. The query itself can match any number of objects, but will return only the first one. It returns null if no objects were matched.If it matched more than one object, the first object from the list is returned. This makes 'selectFirst' different from
Select.selectOne(ObjectContext)
, which would throw in this situation. 'selectFirst' is useful e.g. when the query is ordered and we only want to see the first object (e.g. "most recent news article"), etc.Selecting the first object via "Select.selectFirst(ObjectContext)" is more comprehensible than selecting via "ObjectContext.selectFirst(Select)", because implementations of "Select" set fetch size limit to one.
- Specified by:
selectFirst
in interfaceSelect<T>
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getMetaData
Description copied from class:AbstractQuery
Returns default select parameters.- Specified by:
getMetaData
in interfaceQuery
- Overrides:
getMetaData
in classAbstractQuery
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getBaseMetaData
protected org.apache.cayenne.query.ObjectSelectMetadata getBaseMetaData()- Specified by:
getBaseMetaData
in classCacheableQuery
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createQuery
This method is intended for internal use in aMappedSelect
.- Specified by:
createQuery
in interfaceParameterizedQuery
- Parameters:
parameters
- to apply- Returns:
- this query with parameters applied to the where qualifier
- Since:
- 4.2
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