Class SelectQuery<T>

All Implemented Interfaces:
Serializable, ParameterizedQuery, Query, Select<T>
Direct Known Subclasses:
PrefetchSelectQuery

public class SelectQuery<T>
extends AbstractQuery
implements ParameterizedQuery, Select<T>
A query that selects persistent objects of a certain type or "raw data" (aka DataRows). Supports expression qualifier, multiple orderings and a number of other parameters that serve as runtime hints to Cayenne on how to optimize the fetch and result processing.
See Also:
Serialized Form
  • Field Details

    • DISTINCT_PROPERTY

      public static final String DISTINCT_PROPERTY
      See Also:
      Constant Field Values
    • DISTINCT_DEFAULT

      public static final boolean DISTINCT_DEFAULT
      See Also:
      Constant Field Values
    • qualifier

      protected Expression qualifier
    • orderings

      protected List<Ordering> orderings
    • distinct

      protected boolean distinct
    • columns

      protected Collection<Property<?>> columns
      Since:
      4.0
    • havingQualifier

      protected Expression havingQualifier
      Since:
      4.0
    • canReturnScalarValue

      protected boolean canReturnScalarValue

      Flag that indicates whether this query can return single value or it should always return some complex data (Object[] for now)

      Default value is true

      Since:
      4.0
  • Constructor Details

    • SelectQuery

      public SelectQuery()
      Creates an empty SelectQuery.
    • SelectQuery

      public SelectQuery​(ObjEntity root)
      Creates a SelectQuery with null qualifier, for the specifed ObjEntity
      Parameters:
      root - the ObjEntity this SelectQuery is for.
    • SelectQuery

      public SelectQuery​(ObjEntity root, Expression qualifier)
      Creates a SelectQuery for the specified ObjEntity with the given qualifier.
      Parameters:
      root - the ObjEntity this SelectQuery is for.
      qualifier - an Expression indicating which objects should be fetched
    • SelectQuery

      public SelectQuery​(ObjEntity root, Expression qualifier, List<? extends Ordering> orderings)
      Creates a SelectQuery for the specified ObjEntity with the given qualifier and orderings.
      Parameters:
      root - the ObjEntity this SelectQuery is for.
      qualifier - an Expression indicating which objects should be fetched.
      orderings - defines how to order the results, may be null.
      Since:
      3.1
    • SelectQuery

      public SelectQuery​(Class<T> rootClass)
      Creates a SelectQuery that selects all objects of a given persistent class.
      Parameters:
      rootClass - the Class of objects fetched by this query.
    • SelectQuery

      public SelectQuery​(Class<T> rootClass, Expression qualifier)
      Creates a SelectQuery that selects objects of a given persistent class that match supplied qualifier.
      Parameters:
      rootClass - the Class of objects fetched by this query.
      qualifier - an Expression indicating which objects should be fetched.
    • SelectQuery

      public SelectQuery​(Class<T> rootClass, Expression qualifier, List<? extends Ordering> orderings)
      Creates a SelectQuery that selects objects of a given persistent class that match supplied qualifier.
      Parameters:
      rootClass - the Class of objects fetched by this query.
      qualifier - an Expression indicating which objects should be fetched.
      orderings - defines how to order the results, may be null.
      Since:
      3.1
    • SelectQuery

      public SelectQuery​(DbEntity root)
      Creates a SelectQuery for the specified DbEntity.
      Parameters:
      root - the DbEntity this SelectQuery is for.
      Since:
      1.1
    • SelectQuery

      public SelectQuery​(DbEntity root, Expression qualifier)
      Creates a SelectQuery for the specified DbEntity with the given qualifier.
      Parameters:
      root - the DbEntity this SelectQuery is for.
      qualifier - an Expression indicating which objects should be fetched.
      Since:
      1.1
    • SelectQuery

      public SelectQuery​(DbEntity root, Expression qualifier, List<? extends Ordering> orderings)
      Creates a SelectQuery for the specified DbEntity with the given qualifier and orderings.
      Parameters:
      root - the DbEntity this SelectQuery is for.
      qualifier - an Expression indicating which objects should be fetched.
      orderings - defines how to order the results, may be null.
      Since:
      3.1
    • SelectQuery

      public SelectQuery​(String objEntityName)
      Creates SelectQuery with objEntityName parameter.
    • SelectQuery

      public SelectQuery​(String objEntityName, Expression qualifier)
      Creates SelectQuery with objEntityName and qualifier parameters.
    • SelectQuery

      public SelectQuery​(String objEntityName, Expression qualifier, List<? extends Ordering> orderings)
      Creates a SelectQuery that selects objects of a given persistent class that match supplied qualifier.
      Parameters:
      objEntityName - the name of the ObjEntity to fetch from.
      qualifier - an Expression indicating which objects should be fetched.
      orderings - defines how to order the results, may be null.
      Since:
      3.1
  • Method Details

    • query

      public static <T> SelectQuery<T> query​(Class<T> rootClass)
      Creates a SelectQuery that selects objects of a given persistent class.
      Parameters:
      rootClass - the Class of objects fetched by this query.
      Since:
      4.0
    • query

      public static <T> SelectQuery<T> query​(Class<T> rootClass, Expression qualifier)
      Creates a SelectQuery that selects objects of a given persistent class that match supplied qualifier.
      Parameters:
      rootClass - the Class of objects fetched by this query.
      qualifier - an Expression indicating which objects should be fetched.
      Since:
      4.0
    • query

      public static <T> SelectQuery<T> query​(Class<T> rootClass, Expression qualifier, List<? extends Ordering> orderings)
      Creates a SelectQuery that selects objects of a given persistent class that match supplied qualifier.
      Parameters:
      rootClass - the Class of objects fetched by this query.
      qualifier - an Expression indicating which objects should be fetched.
      orderings - defines how to order the results, may be null.
      Since:
      4.0
    • dataRowQuery

      public static SelectQuery<DataRow> dataRowQuery​(Class<?> rootClass)
      Since:
      4.0
    • dataRowQuery

      public static SelectQuery<DataRow> dataRowQuery​(Class<?> rootClass, Expression qualifier)
      Creates a SelectQuery that selects DataRows that correspond to a given persistent class that match supplied qualifier.
      Parameters:
      rootClass - the Class of objects that correspond to DataRows entity.
      qualifier - an Expression indicating which objects should be fetched.
      Since:
      4.0
    • dataRowQuery

      public static SelectQuery<DataRow> dataRowQuery​(Class<?> rootClass, Expression qualifier, List<Ordering> orderings)
      Since:
      4.0
    • select

      public List<T> select​(ObjectContext context)
      Description copied from interface: Select
      Selects objects using provided context.

      Essentially the inversion of "ObjectContext.select(Select)".

      Specified by:
      select in interface Select<T>
    • selectOne

      public T selectOne​(ObjectContext context)
      Description copied from interface: Select
      Selects a single object using provided context. The query is expected to match zero or one object. It returns null if no objects were matched. If query matched more than one object, CayenneRuntimeException is thrown.

      Essentially the inversion of "ObjectContext.selectOne(Select)".

      Specified by:
      selectOne in interface Select<T>
    • selectFirst

      public T selectFirst​(ObjectContext context)
      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 interface Select<T>
    • iterate

      public void iterate​(ObjectContext context, ResultIteratorCallback<T> callback)
      Description copied from interface: Select
      Creates a ResultIterator based on the provided context and passes it to a callback for processing. The caller does not need to worry about closing the iterator. This method takes care of it.

      Essentially the inversion of "ObjectContext.iterate(Select, ResultIteratorCallback)".

      Specified by:
      iterate in interface Select<T>
    • iterator

      public ResultIterator<T> iterator​(ObjectContext context)
      Description copied from interface: Select
      Creates a ResultIterator based on the provided context. It is usually backed by an open result set and is useful for processing of large data sets, preserving a constant memory footprint. The caller must wrap iteration in try/finally (or try-with-resources for Java 1.7 and higher) and close the ResultIterator explicitly. Or use Select.iterate(ObjectContext, ResultIteratorCallback) as an alternative.

      Essentially the inversion of "ObjectContext.iterator(Select)".

      Specified by:
      iterator in interface Select<T>
    • batchIterator

      public ResultBatchIterator<T> batchIterator​(ObjectContext context, int size)
      Description copied from interface: Select
      Creates a ResultBatchIterator based on the provided context and batch size. It is usually backed by an open result set and is useful for processing of large data sets, preserving a constant memory footprint. The caller must wrap iteration in try/finally (or try-with-resources for Java 1.7 and higher) and close the ResultBatchIterator explicitly.
      Specified by:
      batchIterator in interface Select<T>
    • getMetaData

      public QueryMetadata getMetaData​(EntityResolver resolver)
      Description copied from class: AbstractQuery
      Returns default select parameters.
      Specified by:
      getMetaData in interface Query
      Overrides:
      getMetaData in class AbstractQuery
      Since:
      1.2
    • route

      public void route​(QueryRouter router, EntityResolver resolver, Query substitutedQuery)
      Routes itself and if there are any prefetches configured, creates prefetch queries and routes them as well.
      Specified by:
      route in interface Query
      Overrides:
      route in class AbstractQuery
      Since:
      1.2
    • createSQLAction

      public SQLAction createSQLAction​(SQLActionVisitor visitor)
      Calls "makeSelect" on the visitor.
      Specified by:
      createSQLAction in interface Query
      Specified by:
      createSQLAction in class AbstractQuery
      Since:
      1.2
    • initWithProperties

      public void initWithProperties​(Map<String,​?> properties)
      Initializes query parameters using a set of properties.
      Since:
      1.1
    • queryWithParameters

      public SelectQuery<T> queryWithParameters​(Map<String,​?> parameters)
      A shortcut for queryWithParameters(Map, boolean)that prunes parts of qualifier that have no parameter value set.
    • queryWithParameters

      public SelectQuery<T> queryWithParameters​(Map<String,​?> parameters, boolean pruneMissing)
      Returns a query built using this query as a prototype, using a set of parameters to build the qualifier.
      See Also:
      parameter substitution.
    • createQuery

      public SelectQuery<T> createQuery​(Map<String,​?> parameters)
      Creates and returns a new SelectQuery built using this query as a prototype and substituting qualifier parameters with the values from the map.
      Specified by:
      createQuery in interface ParameterizedQuery
      Since:
      1.1
    • addOrdering

      public void addOrdering​(Ordering ordering)
      Adds ordering specification to this query orderings.
    • addOrderings

      public void addOrderings​(Collection<? extends Ordering> orderings)
      Adds a list of orderings.
    • addOrdering

      public void addOrdering​(String sortPathSpec, SortOrder order)
      Adds ordering specification to this query orderings.
      Since:
      3.0
    • removeOrdering

      public void removeOrdering​(Ordering ordering)
      Removes ordering.
      Since:
      1.1
    • getOrderings

      public List<Ordering> getOrderings()
      Returns a list of orderings used by this query.
    • clearOrderings

      public void clearOrderings()
      Clears all configured orderings.
    • isDistinct

      public boolean isDistinct()
      Returns true if this query returns distinct rows.
    • setDistinct

      public void setDistinct​(boolean distinct)
      Sets distinct property that determines whether this query returns distinct row.
    • setSuppressDistinct

      public void setSuppressDistinct​(boolean suppressDistinct)
      Sets distinct property that determines whether this query returns distinct row.
    • aliasPathSplits

      public void aliasPathSplits​(String path, String... aliases)
      Adds one or more aliases for the qualifier expression path. Aliases serve to instruct Cayenne to generate separate sets of joins for overlapping paths, that maybe needed for complex conditions. An example of an implicit splits is this method: ExpressionFactory.matchAllExp(String, Object...).
      Since:
      3.0
    • getPrefetchTree

      public PrefetchTreeNode getPrefetchTree()
      Since:
      1.2
    • setPrefetchTree

      public void setPrefetchTree​(PrefetchTreeNode prefetchTree)
      Since:
      1.2
    • addPrefetch

      public void addPrefetch​(PrefetchTreeNode prefetchElement)
      Adds a prefetch with specified relationship path to the query.
      Since:
      4.0
    • addPrefetch

      public PrefetchTreeNode addPrefetch​(String prefetchPath)
      Adds a prefetch with specified relationship path to the query.
      Since:
      1.2 signature changed to return created PrefetchTreeNode.
    • clearPrefetches

      public void clearPrefetches()
      Clears all stored prefetch paths.
    • removePrefetch

      public void removePrefetch​(String prefetchPath)
      Removes prefetch.
      Since:
      1.1
    • isFetchingDataRows

      public boolean isFetchingDataRows()
      Returns true if this query should produce a list of data rows as opposed to DataObjects, false for DataObjects. This is a hint to QueryEngine executing this query.
    • setFetchingDataRows

      public void setFetchingDataRows​(boolean flag)
      Deprecated.
      since 4.0, use dataRowQuery(Class, Expression) to create DataRow query instead.
      Sets query result type. If flag parameter is true, then results will be in the form of data rows.

      Note that if the root of this query is a DbEntity, this setting has no effect, and data rows are always fetched.

    • getFetchOffset

      public int getFetchOffset()
      Returns the fetchOffset.
      Since:
      3.0
    • getFetchLimit

      public int getFetchLimit()
      Returns the fetchLimit.
    • setFetchLimit

      public void setFetchLimit​(int fetchLimit)
      Sets the fetchLimit.
    • setFetchOffset

      public void setFetchOffset​(int fetchOffset)
      Since:
      3.0
    • getPageSize

      public int getPageSize()
      Returns pageSize property. See setPageSize for more details.
    • setPageSize

      public void setPageSize​(int pageSize)
      Sets pageSize property. By setting a page size, the Collection returned by performing a query will return hollow DataObjects. This is considerably faster and uses a tiny fraction of the memory compared to a non-paged query when large numbers of objects are returned in the result. When a hollow DataObject is accessed all DataObjects on the same page will be faulted into memory. There will be a small delay when faulting objects while the data is fetched from the data source, but otherwise you do not need to do anything special to access data in hollow objects. The first page is always faulted into memory immediately.
      Parameters:
      pageSize - The pageSize to set
    • setStatementFetchSize

      public void setStatementFetchSize​(int size)
      Sets statement's fetch size (0 for default size)
      Since:
      3.0
    • getStatementFetchSize

      public int getStatementFetchSize()
      Returns:
      statement's fetch size
      Since:
      3.0
    • setQualifier

      public void setQualifier​(Expression qualifier)
      Sets new query qualifier.
    • getQualifier

      public Expression getQualifier()
      Returns query qualifier.
    • andQualifier

      public void andQualifier​(Expression e)
      Adds specified qualifier to the existing qualifier joining it using "AND".
    • orQualifier

      public void orQualifier​(Expression e)
      Adds specified qualifier to the existing qualifier joining it using "OR".
    • setColumns

      public void setColumns​(Collection<Property<?>> columns)
      Since:
      4.0
      See Also:
      setCanReturnScalarValue(boolean)
    • setColumns

      public void setColumns​(Property<?>... columns)
      Since:
      4.0
    • setCanReturnScalarValue

      public void setCanReturnScalarValue​(boolean canReturnScalarValue)

      Flag that indicates whether this query can return single value or it should always return some complex data (Object[] for now)

      Default value is true

      Parameters:
      canReturnScalarValue - can this query return single value
      Since:
      4.0
      See Also:
      setColumns(java.util.Collection<org.apache.cayenne.exp.Property<?>>)
    • canReturnScalarValue

      public boolean canReturnScalarValue()
      Returns:
      can this query return single value
      Since:
      4.0
    • getColumns

      public Collection<Property<?>> getColumns()
      Since:
      4.0
    • setHavingQualifier

      public void setHavingQualifier​(Expression qualifier)
      Sets new query HAVING qualifier.
      Since:
      4.0
    • getHavingQualifier

      public Expression getHavingQualifier()
      Returns query HAVING qualifier.
      Since:
      4.0
    • andHavingQualifier

      public void andHavingQualifier​(Expression e)
      Adds specified HAVING qualifier to the existing HAVING qualifier joining it using "AND".
      Since:
      4.0
    • orHavingQualifier

      public void orHavingQualifier​(Expression e)
      Adds specified HAVING qualifier to the existing HAVING qualifier joining it using "OR".
      Since:
      4.0
    • getBaseMetaData

      protected org.apache.cayenne.query.BaseQueryMetadata getBaseMetaData()
      Specified by:
      getBaseMetaData in class CacheableQuery