Examples of org.eclipse.persistence.expressions.Expression

Package org.eclipse.persistence.expressions

Examples of org.eclipse.persistence.expressions.Expression

org.eclipse.persistence.expressions.Expression
Purpose: Define an object-level representation of a database query where clause.

Description: An expression is a tree-like structure that defines the selection criteria for a query against objects in the database. The expression has the advantage over SQL by being at the object-level, i.e. the object model attributes and relationships can be used to be query on instead of the database field names. Because it is an object, not a string the expression has the advantage that is can be easily manipulated through code to easily build complex selection criterias.

Responsibilities:
- Store the selection criteria in a tree-like structure.
- Support public manipulation protocols for all comparison and function operators.
- Use opperator overloading to support all primitive types as well as objects.

     */
    private ForUpdateOfClause setupLockingClauseForJoinedExpressions(List joinedExpressions, AbstractSession session, ForUpdateOfClause lockingClause) {
        // Must iterate over all of the joined attributes, just check
        // if any of them have pessimistic locking defined on the descriptor.
        for (Iterator e = joinedExpressions.iterator(); e.hasNext();) {
            Expression expression = (Expression)e.next();


            // Expression has not yet been validated.
            if (expression.isObjectExpression()) {
                ObjectExpression joinedAttribute = (ObjectExpression)expression;


                // Expression may not have been initialized.
                joinedAttribute.getBuilder().setSession(session.getRootSession(null));
                if (joinedAttribute.getBuilder().getQueryClass() == null){

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        if (hasCustomDeleteQuery()) {
            return;
        }


        Expression builder = new ExpressionBuilder();
        Expression directKeyExp = builder.getField(getDirectKeyField()).equal(builder.getParameter(getDirectKeyField()));
        Expression expression = null;
        SQLDeleteStatement statement = new SQLDeleteStatement();


        // Construct an expression to delete from the relation table.
        for (int index = 0; index < getReferenceKeyFields().size(); index++) {
            DatabaseField referenceKey = getReferenceKeyFields().get(index);
            DatabaseField sourceKey = getSourceKeyFields().get(index);


            Expression subExp1 = builder.getField(referenceKey);
            Expression subExp2 = builder.getParameter(sourceKey);
            Expression subExpression = subExp1.equal(subExp2);


            expression = subExpression.and(expression);
        }
        expression = expression.and(directKeyExp);
        statement.setWhereClause(expression);
        statement.setTable(getReferenceTable());
        getDeleteQuery().setSQLStatement(statement);

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        if (hasCustomAddTargetQuery) {
            return;
        }


        // Build where clause expression.
        Expression whereClause = null;
        Expression builder = new ExpressionBuilder();


        List<DatabaseField> targetPrimaryKeyFields = getReferenceDescriptor().getPrimaryKeyFields();
        int size = targetPrimaryKeyFields.size();
        for (int index = 0; index < size; index++) {
            DatabaseField targetPrimaryKey = targetPrimaryKeyFields.get(index);
            Expression expression = builder.getField(targetPrimaryKey).equal(builder.getParameter(targetPrimaryKey));
            whereClause = expression.and(whereClause);
        }


        AbstractRecord modifyRow = new DatabaseRecord();
        size = targetForeignKeyFields.size();
        for (int index = 0; index < size; index++) {

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        if (hasCustomRemoveTargetQuery) {
            return;
        }


        // Build where clause expression.
        Expression whereClause = null;
        Expression builder = new ExpressionBuilder();


        List<DatabaseField> targetPrimaryKeyFields = getReferenceDescriptor().getPrimaryKeyFields();
        int size = targetPrimaryKeyFields.size();
        for (int index = 0; index < size; index++) {
            DatabaseField targetPrimaryKey = targetPrimaryKeyFields.get(index);
            Expression expression = builder.getField(targetPrimaryKey).equal(builder.getParameter(targetPrimaryKey));
            whereClause = expression.and(whereClause);
        }


        AbstractRecord modifyRow = new DatabaseRecord();
        size = targetForeignKeyFields.size();
        for (int index = 0; index < size; index++) {
            DatabaseField targetForeignKey = targetForeignKeyFields.get(index);
            modifyRow.put(targetForeignKey, null);
            Expression expression = builder.getField(targetForeignKey).equal(builder.getParameter(targetForeignKey));
            whereClause = expression.and(whereClause);
        }


        SQLUpdateStatement statement = new SQLUpdateStatement();
        statement.setTable(getReferenceDescriptor().getDefaultTable());
        statement.setWhereClause(whereClause);

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        if (hasCustomRemoveAllTargetsQuery) {
            return;
        }


        // Build where clause expression.
        Expression whereClause = null;
        Expression builder = new ExpressionBuilder();


        AbstractRecord modifyRow = new DatabaseRecord();
        int size = targetForeignKeyFields.size();
        for (int index = 0; index < size; index++) {
            DatabaseField targetForeignKey = targetForeignKeyFields.get(index);
            modifyRow.put(targetForeignKey, null);
            Expression expression = builder.getField(targetForeignKey).equal(builder.getParameter(targetForeignKey));
            whereClause = expression.and(whereClause);
        }


        SQLUpdateStatement statement = new SQLUpdateStatement();
        statement.setTable(getReferenceDescriptor().getDefaultTable());
        statement.setWhereClause(whereClause);

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        // this is not persisted so must be hooked back up after loading.
        descriptor.getEventManager().addListener(new DescriptorEventAdapter() {
            public void postBuild(DescriptorEvent event) {
                FunctionExpression expression = (FunctionExpression)event.getObject();
                for (int index = 0; index < expression.getChildren().size(); index++) {
                    Expression child = (Expression)expression.getChildren().get(index);
                    if (child.isValueExpression()) {
                        child.setLocalBase(new ExpressionBuilder());
                    }
                }
                if (expression.getChildren().size() > 0) {
                    expression.setBaseExpression((Expression)expression.getChildren().get(0));
                }

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            public void setAttributeValueInObject(Object object, Object value) {
                if (!(object instanceof ObjectLevelReadQuery)) {
                    return;
                }
                ObjectLevelReadQuery query = (ObjectLevelReadQuery)object;
                Expression expression = (Expression)value;
                if (expression != null) {
                    expression = expression.rebuildOn(query.getExpressionBuilder());
                }
                query.setSelectionCriteria(expression);
            }
        });
        expressionMapping.setReferenceClass(Expression.class);

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            return false;
        }
        if (! ((this.referenceClass == query.referenceClass) || ((this.referenceClass != null) && this.referenceClass.equals(query.referenceClass)))) {
            return false;
        }
        Expression selectionCriteria = getSelectionCriteria();
        Expression otherSelectionCriteria = query.getSelectionCriteria();
        return ((selectionCriteria == otherSelectionCriteria) || ((selectionCriteria != null) && selectionCriteria.equals(otherSelectionCriteria)));
    }

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        }
        int hashCode = 32;
        if (this.referenceClass != null) {
            hashCode = hashCode + this.referenceClass.hashCode();
        }
        Expression selectionCriteria = getSelectionCriteria();
        if (selectionCriteria != null) {
            hashCode = hashCode + selectionCriteria.hashCode();
        }
        return hashCode;
    }

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            // get the expression that we want the table entry for
            QueryKeyExpression baseExpression = (QueryKeyExpression)teExpression.getBaseExpression();
            
            // get the expression that owns the mapping for the table entry
            Expression owningExpression = baseExpression.getBaseExpression();
            ClassDescriptor owningDescriptor = getLeafDescriptorFor(owningExpression, rootDescriptor);
            
            // Get the mapping that owns the table
            CollectionMapping mapping = (CollectionMapping)owningDescriptor.getObjectBuilder().getMappingForAttributeName(baseExpression.getName());
            
            if (teExpression.shouldReturnMapEntry()){
                return mapping;
            }
            if (mapping.getContainerPolicy().isMappedKeyMapPolicy()){
                MappedKeyMapContainerPolicy policy = (MappedKeyMapContainerPolicy)mapping.getContainerPolicy();
                return (DatabaseMapping)policy.getKeyMapping();
            }
            return mapping;
        }


        QueryKeyExpression qkExpression = (QueryKeyExpression)expression;
        Expression baseExpression = qkExpression.getBaseExpression();


        ClassDescriptor descriptor = getLeafDescriptorFor(baseExpression, rootDescriptor);
        if (descriptor == null){
            return null;
        }

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