oracle.toplink.queryframework
Class ObjectLevelReadQuery

java.lang.Object
oracle.toplink.queryframework.DatabaseQuery
oracle.toplink.queryframework.ReadQuery
oracle.toplink.queryframework.ObjectLevelReadQuery

All Implemented Interfaces:

java.lang.Cloneable, oracle.toplink.internal.helper.FalseUndefinedTrue, java.io.Serializable

Direct Known Subclasses:

ReadAllQuery, ReadObjectQuery

public abstract class ObjectLevelReadQuery

extends ReadQuery

Purpose: Abstract class for all read queries using objects.

Description: Contains common behavior for all read queries using objects.

Since:

TOPLink/Java 1.0

See Also:

Serialized Form

Field Summary

static int	CheckCacheByExactPrimaryKey
static int	CheckCacheByPrimaryKey
static int	CheckCacheOnly
static int	CheckCacheThenDatabase
static int	ConformResultsInUnitOfWork
static int	DoNotCheckCache
static short	DONT_USE_DISTINCT
InMemoryQueryIndirectionPolicy	inMemoryQueryIndirectionPolicy Used to determine behaviour of indirection in InMemoryQuerying
static short	LOCK
static short	LOCK_NOWAIT
static short	NO_LOCK
static short	UNCOMPUTED_DISTINCT
static short	USE_DISTINCT
static int	UseDescriptorSetting

Fields inherited from class oracle.toplink.queryframework.DatabaseQuery

CascadeAggregateDelete, CascadeAllParts, CascadeDependentParts, CascadePrivateParts, NoCascading, QUERY_PREPARE

Method Summary

void	acquireLocks() PUBLIC: Set the query to lock, this will also turn refreshCache on.
void	acquireLocksWithoutWaiting() PUBLIC: Set the query to lock without waiting (blocking), this will also turn refreshCache on.
void	addJoinedAttribute(Expression attributeExpression) PUBLIC: Specify the one-to-one mapped attribute to be optimized in this query.
void	addJoinedAttribute(java.lang.String attributeName) PUBLIC: Specify the one-to-one mapped attribute to be optimized in this query.
void	addPartialAttribute(Expression attributeExpression) PUBLIC: Specify that only a subset of the class' attributes be selected in this query.
void	addPartialAttribute(java.lang.String attributeName) PUBLIC: Specify that only a subset of the class' attributes be selected in this query.
void	checkCacheOnly() PUBLIC: The cache will checked completely, if the object is not found null will be returned or an error if the query is too complex.
void	conformResultsInUnitOfWork() PUBLIC: The cache will checked completely, if the object is not found the database will be queried, and the database result will be verified with what is in the cache and/or unit of work including new objects.
void	dontAcquireLocks() PUBLIC: Set the query not to lock.
void	dontCheckCache() PUBLIC: This can be used to explicitly disable the cache hit.
void	dontRefreshIdentityMapResult() PUBLIC: When unset means perform read normally and dont do refresh.
void	dontRefreshRemoteIdentityMapResult() PUBLIC: When unset means perform read normally and dont do refresh.
void	dontUseDistinct() ADVANCED: If a distinct has been set the DISTINCT clause will be printed.
int	getCacheUsage() PUBLIC: Return the cache usage.
short	getDistinctState() ADVANCED: If a distinct has been set the DISTINCT clause will be printed.
java.lang.Object	getExampleObject() PUBLIC: This method returns the current example object.
ExpressionBuilder	getExpressionBuilder() REQUIRED: Get the expression builder which should be used for this query.
InMemoryQueryIndirectionPolicy	getInMemoryQueryIndirectionPolicy() PUBLIC: Returns the InMemoryQueryIndirectionPolicy for this query
short	getLockMode() PUBLIC: Return the current locking mode.
QueryByExamplePolicy	getQueryByExamplePolicy() PUBLIC: When using Query By Example, an instance of QueryByExamplePolicy is used to customize the query.
java.lang.Class	getReferenceClass() PUBLIC: Return the reference class of the query.
boolean	hasJoinedMappings()
boolean	isLockQuery() PUBLIC: Return true if query is in any lockMode other than NO_LOCK
boolean	isObjectLevelReadQuery() PUBLIC: Return if this is an object level read query.
void	refreshIdentityMapResult() PUBLIC: Refresh the attributes of the object(s) resulting from the query.
void	refreshRemoteIdentityMapResult() PUBLIC: Refresh the attributes of the object(s) resulting from the query.
void	resetDistinct() ADVANCED: If a distinct has been set the DISTINCT clause will be printed.
void	setCacheUsage(int cacheUsage) PUBLIC: Set the cache usage.
void	setDistinctState(short distinctState) ADVANCED: If a distinct has been set the DISTINCT clause will be printed.
void	setExampleObject(java.lang.Object newExampleObject) PUBLIC: Set the example object of the query to be the newExampleObject.
void	setInMemoryQueryIndirectionPolicy(InMemoryQueryIndirectionPolicy inMemoryQueryIndirectionPolicy) PUBLIC: Set the InMemoryQueryIndirectionPolicy for this query
void	setLockMode(short lockMode) PUBLIC: Set the lock mode of the query NO_LOCK, LOCK, or LOCK_NOWAIT (default=NO_LOCK)
void	setQueryByExamplePolicy(QueryByExamplePolicy queryByExamplePolicy) PUBLIC: The QueryByExamplePolicy, is a useful to customize the query when Query By Example is used.
void	setReferenceClass(java.lang.Class aClass) REQUIRED: Set the reference class for the query.
void	setShouldRefreshIdentityMapResult(boolean shouldRefreshIdentityMapResult) PUBLIC: Set if the attributes of the object(s) resulting from the query should be refreshed.
void	setShouldRefreshRemoteIdentityMapResult(boolean shouldRefreshIdentityMapResult) PUBLIC: Set if the attributes of the object(s) resulting from the query should be refreshed.
boolean	shouldCheckCacheOnly() PUBLIC: Return if cache should be checked.
boolean	shouldCheckDescriptorForCacheUsage()
boolean	shouldConformResultsInUnitOfWork() PUBLIC: Return if cache should be checked.
boolean	shouldRefreshIdentityMapResult() PUBLIC: Set to a boolean.
boolean	shouldRefreshRemoteIdentityMapResult() PUBLIC: Set to a boolean.
java.lang.String	toString()
void	useDistinct() ADVANCED: If a distinct has been set the DISTINCT clause will be printed.

Methods inherited from class oracle.toplink.queryframework.ReadQuery

cacheQueryResults, clearQueryResults, doNotCacheQueryResults, getMaxRows, isReadQuery, setMaxRows, setShouldCacheQueryResults, shouldCacheQueryResults

Methods inherited from class oracle.toplink.queryframework.DatabaseQuery

addArgument, addArgument, addArgument, addArgumentValue, addArgumentValues, addCall, addStatement, bindAllParameters, cacheStatement, cascadeAllParts, cascadePrivateParts, dontBindAllParameters, dontCacheStatement, dontCascadeParts, dontMaintainCache, getCall, getEJBQLString, getHintString, getName, getQueryTimeout, getRedirector, getSelectionCriteria, getSessionName, getSQLStatement, getSQLString, getTranslatedSQLString, hasSessionName, ignoreBindAllParameters, ignoreCacheStatement, isCallQuery, isDataModifyQuery, isDataReadQuery, isDeleteObjectQuery, isExpressionQuery, isModifyQuery, isObjectLevelModifyQuery, isReadAllQuery, isReadObjectQuery, isReportQuery, isSQLCallQuery, isWriteObjectQuery, maintainCache, prepareCall, setCall, setEJBQLString, setHintString, setName, setQueryTimeout, setRedirector, setSelectionCriteria, setSessionName, setShouldBindAllParameters, setShouldCacheStatement, setShouldMaintainCache, setShouldPrepare, setShouldUseWrapperPolicy, setSQLStatement, setSQLString, shouldBindAllParameters, shouldCacheStatement, shouldCascadeAllParts, shouldCascadeParts, shouldCascadePrivateParts, shouldIgnoreBindAllParameters, shouldIgnoreCacheStatement, shouldMaintainCache, shouldPrepare, shouldUseWrapperPolicy

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

UseDescriptorSetting

public static final int UseDescriptorSetting

See Also:

Constant Field Values

DoNotCheckCache

public static final int DoNotCheckCache

See Also:

Constant Field Values

CheckCacheByExactPrimaryKey

public static final int CheckCacheByExactPrimaryKey

See Also:

Constant Field Values

CheckCacheByPrimaryKey

public static final int CheckCacheByPrimaryKey

See Also:

Constant Field Values

CheckCacheThenDatabase

public static final int CheckCacheThenDatabase

See Also:

Constant Field Values

CheckCacheOnly

public static final int CheckCacheOnly

See Also:

Constant Field Values

ConformResultsInUnitOfWork

public static final int ConformResultsInUnitOfWork

See Also:

Constant Field Values

NO_LOCK

public static final short NO_LOCK

See Also:

Constant Field Values

LOCK

public static final short LOCK

See Also:

Constant Field Values

LOCK_NOWAIT

public static final short LOCK_NOWAIT

See Also:

Constant Field Values

UNCOMPUTED_DISTINCT

public static final short UNCOMPUTED_DISTINCT

See Also:

Constant Field Values

USE_DISTINCT

public static final short USE_DISTINCT

See Also:

Constant Field Values

DONT_USE_DISTINCT

public static final short DONT_USE_DISTINCT

See Also:

Constant Field Values

inMemoryQueryIndirectionPolicy

public InMemoryQueryIndirectionPolicy inMemoryQueryIndirectionPolicy

Used to determine behaviour of indirection in InMemoryQuerying

Method Detail

acquireLocks

public void acquireLocks()

PUBLIC: Set the query to lock, this will also turn refreshCache on.

acquireLocksWithoutWaiting

public void acquireLocksWithoutWaiting()

PUBLIC: Set the query to lock without waiting (blocking), this will also turn refreshCache on.

addJoinedAttribute

public void addJoinedAttribute(java.lang.String attributeName)

PUBLIC: Specify the one-to-one mapped attribute to be optimized in this query. The query will join the object(s) being read with the one-to-one attribute, this allows all of the data required for the object(s) to be read in a single query instead of (n) queries. This should be used when the application knows that it requires the part for all of the objects being read. This can be used only for one-to-one mappings where the target is not the same class as the source, either directly or through inheritance. Also two joins cannot be done to the same class.

Note: This cannot be used for objects where it is possible not to have a part, as these objects will be ommited from the result set, unless an outer join is used through passing and expression using "getAllowingNull".

Example: query.addJoinedAttribute("address")

See Also:

addJoinedAttribute(Expression), ReadAllQuery.addBatchReadAttribute(Expression)

addJoinedAttribute

public void addJoinedAttribute(Expression attributeExpression)

PUBLIC: Specify the one-to-one mapped attribute to be optimized in this query. The query will join the object(s) being read with the one-to-one attribute, this allows all of the data required for the object(s) to be read in a single query instead of (n) queries. This should be used when the application knows that it requires the part for all of the objects being read. This can be used only for one-to-one mappings where the target is not the same class as the source, either directly or through inheritance. Also two joins cannot be done to the same class.

Note: This cannot be used for objects where it is possible not to have a part, as these objects will be ommited from the result set, unless an outer join is used through passing and expression using "getAllowingNull".

Example: query.addJoinedAttribute(query.getExpressionBuilder().get("teamLeader").get("address"))

See Also:

ReadAllQuery.addBatchReadAttribute(String)

addPartialAttribute

public void addPartialAttribute(java.lang.String attributeName)

PUBLIC: Specify that only a subset of the class' attributes be selected in this query.

This allows for the query to be optimized through selecting less data.

Partial objects will be returned from the query, where the unspecified attributes will be left null. The primary key will always be selected to allow re-querying of the whole object.

Note: Because the object is not fully initialized it cannot be cached, and cannot be edited.

Note: You cannot have 2 partial attributes of the same type. You also cannot add a partial attribute which is of the same type as the class being queried.

Example: query.addPartialAttribute("firstName")

See Also:

addPartialAttribute(Expression)

addPartialAttribute

public void addPartialAttribute(Expression attributeExpression)

PUBLIC: Specify that only a subset of the class' attributes be selected in this query.

This allows for the query to be optimized through selecting less data.

Partial objects will be returned from the query, where the unspecified attributes will be left null. The primary key will always be selected to allow re-querying of the whole object.

Note: Because the object is not fully initialized it cannot be cached, and cannot be edited.

Note: You cannot have 2 partial attributes of the same type. You also cannot add a partial attribute which is of the same type as the class being queried.

Example: query.addPartialAttribute(query.getExpressionBuilder().get("address").get("city"))

checkCacheOnly

public void checkCacheOnly()

PUBLIC: The cache will checked completely, if the object is not found null will be returned or an error if the query is too complex. Queries can be configured to use the cache at several levels. Other caching option are available.

See Also:

setCacheUsage(int)

conformResultsInUnitOfWork

public void conformResultsInUnitOfWork()

PUBLIC: The cache will checked completely, if the object is not found the database will be queried, and the database result will be verified with what is in the cache and/or unit of work including new objects. This can lead to poor performance so it is recomended that only the database be queried in most cases. Queries can be configured to use the cache at several levels. Other caching option are available.

See Also:

setCacheUsage(int)

dontAcquireLocks

public void dontAcquireLocks()

PUBLIC: Set the query not to lock.

dontCheckCache

public void dontCheckCache()

PUBLIC: This can be used to explicitly disable the cache hit. The cache hit may not be desired in some cases, such as stored procedures that accept the primary key but do not query on it.

dontRefreshIdentityMapResult

public void dontRefreshIdentityMapResult()

PUBLIC: When unset means perform read normally and dont do refresh.

dontRefreshRemoteIdentityMapResult

public void dontRefreshRemoteIdentityMapResult()

PUBLIC: When unset means perform read normally and dont do refresh.

dontUseDistinct

public void dontUseDistinct()

ADVANCED: If a distinct has been set the DISTINCT clause will be printed. This is used internally by TopLink for batch reading but may also be used directly for advanced queries or report queries.

getCacheUsage

public int getCacheUsage()

PUBLIC: Return the cache usage. By default only primary key read object queries will first check the cache before accessing the database. Any query can be configure to query against the cache completely, by key or ignore the cache check.

Valid values are:

• DoNotCheckCache
• CheckCacheByExactPrimaryKey
• CheckCacheByPrimaryKey
• CheckCacheThenDatabase
• CheckCacheOnly
• ConformResultsAgainstCache </lu>

  getDistinctState

  public short getDistinctState()
  

  ADVANCED: If a distinct has been set the DISTINCT clause will be printed. This is used internally by TopLink for batch reading but may also be used directly for advanced queries or report queries.

  getExampleObject

  public java.lang.Object getExampleObject()
  

  PUBLIC: This method returns the current example object. The "example" object is an actual domain object, provided by the client, from which an expression is generated. This expression is used for a query of all objects from the same class, that match the attribute values of the "example" object.

  getExpressionBuilder

  public ExpressionBuilder getExpressionBuilder()
  

  REQUIRED: Get the expression builder which should be used for this query. This expression builder should be used to build all expressions used by this query.

  getInMemoryQueryIndirectionPolicy

  public InMemoryQueryIndirectionPolicy getInMemoryQueryIndirectionPolicy()
  

  PUBLIC: Returns the InMemoryQueryIndirectionPolicy for this query

  getLockMode

  public short getLockMode()
  

  PUBLIC: Return the current locking mode.

  getQueryByExamplePolicy

  public QueryByExamplePolicy getQueryByExamplePolicy()
  

  PUBLIC: When using Query By Example, an instance of QueryByExamplePolicy is used to customize the query. The policy is useful when special operations are to be used for comparisons (notEqual, lessThan, greaterThan, like etc.), when a certain value is to be ignored, or when dealing with nulls.

  getReferenceClass

  public java.lang.Class getReferenceClass()
  

  PUBLIC: Return the reference class of the query.

  Overrides:

  getReferenceClass in class DatabaseQuery

  hasJoinedMappings

  public boolean hasJoinedMappings()
  

  isLockQuery

  public boolean isLockQuery()
  

  PUBLIC: Return true if query is in any lockMode other than NO_LOCK

  isObjectLevelReadQuery

  public boolean isObjectLevelReadQuery()
  

  PUBLIC: Return if this is an object level read query.

  Overrides:

  isObjectLevelReadQuery in class DatabaseQuery

  refreshIdentityMapResult

  public void refreshIdentityMapResult()
  

  PUBLIC: Refresh the attributes of the object(s) resulting from the query. If cascading is used the private parts of the objects will also be refreshed.

  refreshRemoteIdentityMapResult

  public void refreshRemoteIdentityMapResult()
  

  PUBLIC: Refresh the attributes of the object(s) resulting from the query. If cascading is used the private parts of the objects will also be refreshed.

  resetDistinct

  public void resetDistinct()
  

  ADVANCED: If a distinct has been set the DISTINCT clause will be printed. This is used internally by TopLink for batch reading but may also be used directly for advanced queries or report queries.

  setCacheUsage

  public void setCacheUsage(int cacheUsage)
  

  PUBLIC: Set the cache usage. By default only primary key read object queries will first check the cache before accessing the database. Any query can be configure to query against the cache completely, by key or ignore the cache check.

  Valid values are:

  • DoNotCheckCache - The query does not check the cache but accesses the database, the cache will still be maintain.
  • CheckCacheByExactPrimaryKey - If the query is exactly and only on the object's primary key the cache will be checked.
  • CheckCacheByPrimaryKey - If the query contains the primary key and possible other values the cache will be checked.
  • CheckCacheThenDatabase - The whole cache will be checked to see if there is any object matching the query, if not the database will be accessed.
  • CheckCacheOnly - The whole cache will be checked to see if there is any object matching the query, if not null or an empty collection is returned.
  • ConformResultsAgainstUnitOfWork - The results will be checked againtst the changes within the unit of work and object no longer matching or deleted will be remove, matching new objects will also be added. </lu>

    setDistinctState

    public void setDistinctState(short distinctState)
    

    ADVANCED: If a distinct has been set the DISTINCT clause will be printed. This is used internally by TopLink for batch reading but may also be used directly for advanced queries or report queries.

    setExampleObject

    public void setExampleObject(java.lang.Object newExampleObject)
    

    PUBLIC: Set the example object of the query to be the newExampleObject. The example object is used for Query By Example. When doing a Query By Example, an instance of the desired object is created, and the fields are filled with the values that are required in the result set. From these values the corresponding expression is built by TopLink, and the query is executed, returning the set of results.

    If a query already has a selection criteria this criteria and the generated query by example criteria will be conjuncted.

    Once a query is executed you must make an explicit call to setExampleObject if the example object is changed, so the query will know to prepare itself again.

    There is a caution to setting both a selection criteria and an example object: Only in this case if you set the example object again after execution you must then also reset the selection criteria. (This is because after execution the original criteria and Query By Example criteria were fused together, and the former cannot be easily recovered from the now invalid result).

    setInMemoryQueryIndirectionPolicy

    public void setInMemoryQueryIndirectionPolicy(InMemoryQueryIndirectionPolicy inMemoryQueryIndirectionPolicy)
    

    PUBLIC: Set the InMemoryQueryIndirectionPolicy for this query

    setLockMode

    public void setLockMode(short lockMode)
    

    PUBLIC: Set the lock mode of the query NO_LOCK, LOCK, or LOCK_NOWAIT (default=NO_LOCK)

    setQueryByExamplePolicy

    public void setQueryByExamplePolicy(QueryByExamplePolicy queryByExamplePolicy)
    

    PUBLIC: The QueryByExamplePolicy, is a useful to customize the query when Query By Example is used. The policy will control what attributes should, or should not be included in the query. When dealing with nulls, using specail operations (notEqual, lessThan, like, etc.) for comparison, or chosing to include certain attributes at all times, it is useful to modify the policy accordingly.

    Once a query is executed you must make an explicit call to setQueryByExamplePolicy when changing the policy, so the query will know to prepare itself again.

    There is a caution to setting both a selection criteria and an example object: If you set the policy after execution you must also reset the selection criteria. (This is because after execution the original criteria and Query By Example criteria are fused together, and the former cannot be easily recovered).

    setReferenceClass

    public void setReferenceClass(java.lang.Class aClass)
    

    REQUIRED: Set the reference class for the query.

    setShouldRefreshIdentityMapResult

    public void setShouldRefreshIdentityMapResult(boolean shouldRefreshIdentityMapResult)
    

    PUBLIC: Set if the attributes of the object(s) resulting from the query should be refreshed. If cascading is used the private parts of the objects will also be refreshed.

    setShouldRefreshRemoteIdentityMapResult

    public void setShouldRefreshRemoteIdentityMapResult(boolean shouldRefreshIdentityMapResult)
    

    PUBLIC: Set if the attributes of the object(s) resulting from the query should be refreshed. If cascading is used the private parts of the objects will also be refreshed.

    shouldCheckCacheOnly

    public boolean shouldCheckCacheOnly()
    

    PUBLIC: Return if cache should be checked.

    shouldCheckDescriptorForCacheUsage

    public boolean shouldCheckDescriptorForCacheUsage()
    

    shouldConformResultsInUnitOfWork

    public boolean shouldConformResultsInUnitOfWork()
    

    PUBLIC: Return if cache should be checked.

    shouldRefreshIdentityMapResult

    public boolean shouldRefreshIdentityMapResult()
    

    PUBLIC: Set to a boolean. When set means refresh the instance variables of referenceObject from the database.

    shouldRefreshRemoteIdentityMapResult

    public boolean shouldRefreshRemoteIdentityMapResult()
    

    PUBLIC: Set to a boolean. When set means refresh the instance variables of referenceObject from the database.

    toString

    public java.lang.String toString()
    

    Overrides:

    toString in class DatabaseQuery

    useDistinct

    public void useDistinct()
    

    ADVANCED: If a distinct has been set the DISTINCT clause will be printed. This is used internally by TopLink for batch reading but may also be used directly for advanced queries or report queries.