Class DataExpression
- All Implemented Interfaces:
Serializable
,Cloneable
- Direct Known Subclasses:
ClassTypeExpression
,FieldExpression
,ObjectExpression
,TableExpression
- See Also:
-
Field Summary
Modifier and TypeFieldDescriptionprotected AsOfClause
protected List
<Expression> protected List
<Expression> protected boolean
protected TableAliasLookup
Fields inherited from class org.eclipse.persistence.internal.expressions.BaseExpression
baseExpression, builder
Fields inherited from class org.eclipse.persistence.expressions.Expression
currentAlias, hashCode, lastTable, selectIfOrderedBy, shouldUseUpperCaseForIgnoreCase
-
Constructor Summary
-
Method Summary
Modifier and TypeMethodDescriptionvoid
addDerivedField
(Expression addThis) void
addDerivedTable
(Expression addThis) aliasForTable
(DatabaseTable table) INTERNAL: Find the alias for a given tableasOf
(AsOfClause clause) Sets all tables represented by this expression to be queried as of a past time.protected void
assignAlias
(String name, DatabaseTable table) INTERNAL: Alias a particular table within this nodeprotected void
assignAlias
(DatabaseTable alias, DatabaseTable table) INTERNAL: Alias a particular table within this nodevoid
INTERNAL:copyCollection
(List<Expression> in, Map alreadyDone) boolean
INTERNAL: Return if the expression is equal to the other.INTERNAL:INTERNAL:getAlias
(Expression subSelect) ADVANCED: Return an expression representing a sub-select in the from clause.INTERNAL: Return the field appropriately aliasedAnswers the past time the expression is explicitly as of.INTERNAL: Return the descriptor which contains this query key.getField()
INTERNAL:ADVANCED: Return an expression representing a field in a data-level query.getField
(DatabaseField field) ADVANCED: Return an expression representing a field in a data-level query.ADVANCED: Return an expression representing a table in a data-level query.getTable
(DatabaseTable table) ADVANCED: Return an expression representing a table in a data-level query.INTERNAL: Return the aliases used.boolean
ADVANCED: Answers true ifthis
is to be queried as of a past time.boolean
INTERNAL: Answers if the database tables associated with this expression have been aliased.boolean
INTERNAL: Did the normalizer already add additional joins to the where clause due to this query key representing a foreign reference mapping? This insures that join criteria (for any query key expression) is not added twice.protected boolean
protected boolean
boolean
INTERNAL:boolean
INTERNAL:void
iterateOn
(ExpressionIterator iterator) INTERNAL: For iterating using an inner classnewDerivedField
(DatabaseField field) INTERNAL:newDerivedTable
(DatabaseTable table) INTERNAL:normalize
(ExpressionNormalizer normalizer) INTERNAL: Normalize the expression into a printable structure.protected void
postCopyIn
(Map alreadyDone) INTERNAL: Used for cloning.void
printSQL
(ExpressionSQLPrinter printer) INTERNAL: Print SQL onto the stream, using the ExpressionPrinter for contextvoid
setHasBeenNormalized
(boolean value) void
setTableAliases
(TableAliasLookup tableAliases) INTERNAL: For CR#2456, Table identity involves having two tables sharing the same aliasing table.void
writeSubexpressionsTo
(BufferedWriter writer, int indent) Print the base for debuggin purposes.Methods inherited from class org.eclipse.persistence.internal.expressions.BaseExpression
getBaseExpression, getBuilder, resetPlaceHolderBuilder, setBaseExpression, shallowClone
Methods inherited from class org.eclipse.persistence.expressions.Expression
addDate, addDate, addMonths, addMonths, alias, all, all, all, all, all, all, all, all, all, all, all, all, allOf, and, any, any, any, any, any, any, any, any, any, any, any, any, anyOf, anyOf, anyOfAllowingNone, anyOfAllowingNone, as, ascending, asciiValue, assignTableAliasesStartingAt, average, between, between, between, between, between, between, between, between, between, caseConditionStatement, caseConditionStatement, caseStatement, caseStatement, cast, clone, cloneUsing, coalesce, coalesce, computeHashCode, concat, containsAllKeyWords, containsAnyKeyWords, containsSubstring, containsSubstring, containsSubstringIgnoringCase, containsSubstringIgnoringCase, convertNodeToUseOuterJoin, convertToUseOuterJoin, copiedVersionFrom, count, create, create, createWithBaseLast, currentDate, currentDateDate, currentTime, currentTimeStamp, dateDifference, dateDifference, dateName, datePart, dateToString, decode, descending, descriptionOfNodeType, difference, distinct, doesConform, doesConform, equal, equal, equal, equal, equal, equal, equal, equal, equal, equal, equalOuterJoin, equalOuterJoin, equalsIgnoreCase, equalsIgnoreCase, except, except, exceptAll, exceptAll, exists, existsNode, extract, extractFields, extractPrimaryKeyValues, extractValue, extractValues, extractXml, from, fromConstant, fromLiteral, get, get, getAllowingNull, getAsOfClauseRecursively, getClonedField, getFields, getFieldValue, getFunction, getFunction, getFunction, getFunction, getFunctionWithArguments, getLeafDescriptor, getLeafMapping, getName, getNumberVal, getOperator, getOperator, getOwnedTables, getParameter, getParameter, getParameter, getProperty, getSelectionFields, getSelectionFields, getSession, getStringVal, greaterThan, greaterThan, greaterThan, greaterThan, greaterThan, greaterThan, greaterThan, greaterThan, greaterThan, greaterThan, greaterThanEqual, greaterThanEqual, greaterThanEqual, greaterThanEqual, greaterThanEqual, greaterThanEqual, greaterThanEqual, greaterThanEqual, greaterThanEqual, greaterThanEqual, hashCode, hexToRaw, ifNull, in, in, in, in, in, in, in, in, in, in, in, in, index, indexOf, intersect, intersect, intersectAll, intersectAll, isClassTypeExpression, isCompoundExpression, isConstantExpression, isEmpty, isExpressionBuilder, isFieldExpression, isFragment, isFunctionExpression, isLiteralExpression, isLogicalExpression, isMapEntryExpression, isNull, isObjectExpression, isParameterExpression, isQueryKeyExpression, isRelationExpression, isSubSelectExpression, isTableExpression, isTreatExpression, isValueExpression, join, lastDay, leftJoin, leftPad, leftPad, leftTrim, leftTrim, length, lessThan, lessThan, lessThan, lessThan, lessThan, lessThan, lessThan, lessThan, lessThan, lessThan, lessThanEqual, lessThanEqual, lessThanEqual, lessThanEqual, lessThanEqual, lessThanEqual, lessThanEqual, lessThanEqual, lessThanEqual, lessThanEqual, like, like, like, like, likeIgnoreCase, likeIgnoreCase, literal, localDate, localDateTime, localTime, locate, locate, locate, mapEntry, mapKey, maximum, minimum, monthsBetween, newTime, nextDay, noneOf, not, notBetween, notBetween, notBetween, notBetween, notBetween, notBetween, notBetween, notBetween, notBetween, notEmpty, notEqual, notEqual, notEqual, notEqual, notEqual, notEqual, notEqual, notEqual, notEqual, notEqual, notExists, notIn, notIn, notIn, notIn, notIn, notIn, notIn, notIn, notIn, notIn, notIn, notIn, notLike, notLike, notLike, notLike, notNull, nullIf, nullsFirst, nullsLast, operator, or, performOperator, postfixSQL, prefixSQL, printJava, rebuildOn, ref, regexp, regexp, registerIn, replace, replicate, replicate, resetCache, reverse, right, right, rightPad, rightPad, rightTrim, rightTrim, roundDate, selectIfOrderedBy, setLocalBase, setSelectIfOrderedBy, size, size, some, some, some, some, some, some, some, some, some, some, some, some, sql, standardDeviation, subQuery, substring, substring, substring, substring, sum, toChar, toChar, toCharacter, toDate, toLowerCase, toNumber, toString, toString, toUpperCase, toUppercaseCasedWords, translate, treat, trim, trim, truncateDate, twist, twistedForBaseAndContext, type, union, union, unionAll, unionAll, validateNode, value, value, value, value, value, value, value, value, value, value, valueFromObject, valueFromObject, variance, writeAlias, writeDescriptionOn, writeField, writeFields
-
Field Details
-
derivedTables
-
derivedFields
-
hasBeenNormalized
protected boolean hasBeenNormalized -
tableAliases
-
asOfClause
-
-
Constructor Details
-
DataExpression
protected DataExpression()DataExpression constructor comment.
-
-
Method Details
-
equals
INTERNAL: Return if the expression is equal to the other. This is used to allow dynamic expression's SQL to be cached.- Overrides:
equals
in classExpression
-
addDerivedField
-
addDerivedTable
-
asOf
Description copied from class:Expression
Sets all tables represented by this expression to be queried as of a past time.Example:
EclipseLink: employee.asOf(new AsOfClause(pastTime)) Java: None SQL (Flashback): SELECT ... FROM EMPLOYEE AS OF TIMESTAMP (pastTime) t0 ... SQL (Generic): .. WHERE (t1.START <= pastTime) AND ((t1.END IS NULL) OR t1.END > pastTime)
Set an as of clause at the expression level to still query for current objects while expressing selection criteria like:
- query objects as of one time that met some condition at another time.
- query objects that changed a certain way over a certain interval (querying for change).
Simultaneously querying on two versions of the same object (one past one present) lets you express these advanced selection criteria.
Example: Querying on past attributes using parallel expressions.
// Finds all employees who lived in Ottawa as of a past time. ExpressionBuilder employee = new ExpressionBuilder(); ExpressionBuilder pastEmployee = new ExpressionBuilder(Employee.class); pastEmployee.asOf(pastTime); Expression pastAddress = pastEmployee.get("address"); // by default address will also be as of past time. Expression selectionCriteria = pastAddress.get("city").equal("Ottawa").and( employee.equal(pastEmployee));
The advantage of the parallel expression is that you can still read current objects, the as of clause will affect only the where clause / selection criteria.
You may be tempted to rewrite the above as employee.get("address").asOf(pastTime). That is allowed but see below for the finer points involved in this.
Example: Querying on object changes using parallel expressions.
// Finds all employees who recently received a raise. Note that current // objects are returned, so can be cached normally. ExpressionBuilder employee = new ExpressionBuilder(); Expression pastEmployee = new ExpressionBuilder(Employee.class); pastEmployee.asOf(yesterday); Expression parallelJoin = employee.equal(pastEmployee); Expression selectionCriteria = parallelJoin.and( employee.get("salary").greaterThan(pastEmployee.get("salary")));
Example: Querying on object changes using custom query keys
// First define the custom query key and add it to your descriptor. ExpressionBuilder builder = new ExpressionBuilder(Employee.class); Expression joinCriteria = builder.getField("EMPLOYEE.EMP_ID").equal(builder.getParameter("EMPLOYEE.EMP_ID")); OneToOneQueryKey selfReferential = new OneToOneQueryKey(); selfReferential.setName("this"); selfReferential.setJoinCriteria(joinCriteria); selfReferential.setReferenceClass(Employee.class); getSession().getDescriptor(Employee.class).addQueryKey(selfReferential); // Now build query as before. Expression employee = new ExpessionBuilder(); Expression pastEmployee = employee.get("this").asOf(yesterday); Expression selectionCriteria = employee.get("salary").greaterThan(pastEmployee.get("salary"));
Note in general that any parallel expression can be rewritten using a custom query key. EclipseLink will even automatically interpret x.get("this") for you so you do not need to define the above query key first.
Full Reference:
If an object is mapped to multiple tables, then each table will be as of the same time. Two objects mapped to the same table can not have different as of times. Conversely only expressions which have associated tables can have an as of clause.
If an as of clause is not explicitly set an expression will use the clause of its base expression, and so on recursively until one is found or an ExpressionBuilder is reached. Some usage scenarios follow:
- employee.asOf(pastTime).anyOf("projects"): projects as of past time.
- expressionBuilder.asOf(pastTime): entire expression as of past time.
- employee.asOf(pastTime).anyOf("projects").asOf(null): projects as of current time.
- employee.anyOf("projects").asOf(pastTime): projects only as of past time.
Watch out for x.asOf(oneTime).get("y").asOf(anotherTime).
- emp.anyOf("phoneNumbers").asOf(yesterday) = emp.asOf(yesterday).anyOf("phoneNumbers") but:
- emp.get("address").asOf(yesterday) != emp.asOf(yesterday).get("address").
- Overrides:
asOf
in classExpression
- Parameters:
clause
- A read only data object used to represent a past time.- Returns:
this
- See Also:
-
aliasForTable
INTERNAL: Find the alias for a given table- Overrides:
aliasForTable
in classExpression
-
assignAlias
INTERNAL: Alias a particular table within this node- Overrides:
assignAlias
in classExpression
-
assignAlias
INTERNAL: Alias a particular table within this node -
clearAliases
public void clearAliases()INTERNAL: -
copyCollection
-
existingDerivedField
INTERNAL: -
existingDerivedTable
INTERNAL: -
getAliasedField
INTERNAL: Return the field appropriately aliased -
getAsOfClause
Description copied from class:Expression
Answers the past time the expression is explicitly as of.- Overrides:
getAsOfClause
in classExpression
- Returns:
- An immutable object representation of the past time.
null
if no clause set,AsOfClause.NO_CLAUSE
if clause explicitly set tonull
. - See Also:
-
getDescriptor
-
getField
INTERNAL: -
getField
Description copied from class:Expression
ADVANCED: Return an expression representing a field in a data-level query. This is used internally in EclipseLink, or to construct queries involving fields and/or tables that are not mapped.Example:
builder.getField("ADDR_ID").greaterThan(100); builder.getTable("PROJ_EMP").getField("TYPE").equal("S");
- Overrides:
getField
in classExpression
-
getField
Description copied from class:Expression
ADVANCED: Return an expression representing a field in a data-level query. This is used internally in EclipseLink, or to construct queries involving fields and/or tables that are not mapped.Example:
builder.getField(aField).greaterThan(100);
- Overrides:
getField
in classExpression
-
getContainingDescriptor
INTERNAL: Return the descriptor which contains this query key. -
getMapping
-
getQueryKeyOrNull
-
getTable
Description copied from class:Expression
ADVANCED: Return an expression representing a table in a data-level query. This is used internally in EclipseLink, or to construct queries involving fields and/or tables that are not mapped.Example:
builder.getTable("PROJ_EMP").getField("TYPE").equal("S");
- Overrides:
getTable
in classExpression
-
getTable
Description copied from class:Expression
ADVANCED: Return an expression representing a table in a data-level query. This is used internally in EclipseLink, or to construct queries involving fields and/or tables that are not mapped.Example:
builder.getTable(linkTable).getField("TYPE").equal("S");
- Overrides:
getTable
in classExpression
-
getTableAliases
INTERNAL: Return the aliases used. For CR#2456 must never lazily initialize as also used for Expression identity.- Overrides:
getTableAliases
in classExpression
-
hasBeenNormalized
public boolean hasBeenNormalized()INTERNAL: Did the normalizer already add additional joins to the where clause due to this query key representing a foreign reference mapping? This insures that join criteria (for any query key expression) is not added twice.New meaning: DataExpressions are often iterated on multiple times during normalize, but Function/Relation expressions only once. Adding a has been normalized flag improves performance and is required in some applications, such as have temporal query criteria been added.
-
hasAsOfClause
public boolean hasAsOfClause()Description copied from class:Expression
ADVANCED: Answers true ifthis
is to be queried as of a past time.- Overrides:
hasAsOfClause
in classExpression
- Returns:
- false from
asOf(null); hasAsOfClause()
. - See Also:
-
hasBeenAliased
public boolean hasBeenAliased()Description copied from class:Expression
INTERNAL: Answers if the database tables associated with this expression have been aliased. This insures the same tables are not aliased twice.- Overrides:
hasBeenAliased
in classExpression
-
hasDerivedFields
protected boolean hasDerivedFields() -
hasDerivedTables
protected boolean hasDerivedTables() -
isAttribute
public boolean isAttribute()INTERNAL: -
isDataExpression
public boolean isDataExpression()Description copied from class:Expression
INTERNAL:- Overrides:
isDataExpression
in classExpression
-
iterateOn
INTERNAL: For iterating using an inner class- Overrides:
iterateOn
in classExpression
-
newDerivedField
INTERNAL: -
newDerivedTable
INTERNAL: -
getAlias
ADVANCED: Return an expression representing a sub-select in the from clause.Example:
builder.getAlias(builder.subQuery(reportQuery)).get("type").equal("S");
- Overrides:
getAlias
in classExpression
-
normalize
INTERNAL: Normalize the expression into a printable structure. Any joins must be added to form a new root.- Overrides:
normalize
in classExpression
-
postCopyIn
INTERNAL: Used for cloning.- Overrides:
postCopyIn
in classBaseExpression
-
printSQL
INTERNAL: Print SQL onto the stream, using the ExpressionPrinter for context- Specified by:
printSQL
in classExpression
-
setHasBeenNormalized
public void setHasBeenNormalized(boolean value) -
setTableAliases
INTERNAL: For CR#2456, Table identity involves having two tables sharing the same aliasing table. -
tableAliasesDescription
-
writeSubexpressionsTo
Print the base for debuggin purposes.- Overrides:
writeSubexpressionsTo
in classExpression
- Throws:
IOException
-