Examples of oracle.toplink.essentials.expressions.Expression

Package oracle.toplink.essentials.expressions

Examples of oracle.toplink.essentials.expressions.Expression

oracle.toplink.essentials.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 opperators.
- Use opperator overloading to support all primitive types as well as objects.

     * INTERNAL
     * @param context The generation context
     * @return A TopLink expression
     */
    public Expression generateExpression(GenerationContext context) {
        Expression whereClause = null;
        if (getLeft() != null) {
            whereClause = getLeft().generateExpression(context);
        }
        return whereClause;
    }

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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 = (DatabaseField)getReferenceKeyFields().elementAt(index);
            DatabaseField sourceKey = (DatabaseField)getSourceKeyFields().elementAt(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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    public Expression joinVariables(Set variables) {
        if ((outer == null) || (variables == null) || variables.isEmpty()) {
            // not an inner query or no variables to join
            return null;
        }
        Expression expr = null;
        for (Iterator i = variables.iterator(); i.hasNext(); ) {
            String name = (String)i.next();
            VariableNode var = new VariableNode(name);
            Expression innerExpr = var.generateExpression(this);
            Expression outerExpr = var.generateExpression(outer);
            Expression join = innerExpr.equal(outerExpr);
            expr = var.appendExpression(expr, join);
        }
        return expr;
    }

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        //need pessimistic locking for the locator select
        selectStatement.setLockingClause(ForUpdateClause.newInstance(ObjectBuildingQuery.LOCK));


        if (tables.size() > 1) {
            //the primary key expression from the primary table
            Expression expression = selectStatement.getWhereClause();


            //additioanl join from the non-primary tables
            Expression additionalJoin = (Expression)writeQuery.getDescriptor().getQueryManager().getAdditionalJoinExpression();
            if (additionalJoin != null) {
                expression = expression.and(additionalJoin);
            }


            //where clause now contains extra joins across all tables

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     * INTERNAL
     * Add the having expression to the passed query
     */
    public void addHavingToQuery(ObjectLevelReadQuery theQuery, GenerationContext context) {
        if (theQuery.isReportQuery()) {
            Expression havingExpression = getHaving().generateExpression(context);
            ((ReportQuery)theQuery).setHavingExpression(havingExpression);
        }
    }

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    public void addAggregateOrderBy(String aggregateName, String queryKeyName, boolean isDescending) {
        this.hasOrderBy = true;
        
        ReadAllQuery readAllQuery = (ReadAllQuery) getSelectionQuery();
        ExpressionBuilder builder = readAllQuery.getExpressionBuilder();
        Expression expression = builder.get(aggregateName).get(queryKeyName).toUpperCase();
        
        if (isDescending) {
            readAllQuery.addOrdering(expression.descending());
        } else {
            readAllQuery.addOrdering(expression.ascending());
        }
    }

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     * INTERNAL
     * Return a TopLink expression generated using the left node
     */
    public Expression generateExpression(GenerationContext context) {
        String name = getAsString();
        Expression aggregateExpr = context.expressionFor(name);
        if (aggregateExpr == null) {
            Expression arg = getLeft().generateExpression(context);
            if (usesDistinct()) {
                arg = arg.distinct();
            }
            aggregateExpr = addAggregateExression(arg);
            context.addExpression(aggregateExpr, name);
        }
        return aggregateExpr;

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        //that they should check the SelectNode before resolving.
        //If the variable involved is SELECTed, then we want an empty builder
        //instead (with an empty constructor).
        boolean oldCheckState = context.shouldCheckSelectNodeBeforeResolving();
        ((SelectGenerationContext)context).checkSelectNodeBeforeResolving(true);
        Expression orderByExpression = getOrderByItem().generateExpression(context);
        orderByExpression = getDirection().addToExpression(orderByExpression, context);
        ((SelectGenerationContext)context).checkSelectNodeBeforeResolving(oldCheckState);
        return orderByExpression;
    }

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     */
    public void prepareJoinExpressions(AbstractSession session) {
        // The prepareJoinExpression check for outer-joins to set this to true.
        setIsOuterJoinedAttributeQuery(false);
        for (int index = 0; index < getJoinedAttributeExpressions().size(); index++) {
            Expression expression = (Expression)getJoinedAttributeExpressions().get(index);
            if(expression.isObjectExpression()) {
                ((ObjectExpression)expression).setShouldUseOuterJoinForMultitableInheritance(true);
            }
            prepareJoinExpression(expression, session);
        }
        for (int index = 0; index < getJoinedMappingExpressions().size(); index++) {
            Expression expression = (Expression)getJoinedMappingExpressions().get(index);
            if(expression.isObjectExpression()) {
                ((ObjectExpression)expression).setShouldUseOuterJoinForMultitableInheritance(true);
            }
            prepareJoinExpression(expression, session);
        }
        computeJoiningMappingQueries(session);

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     */
    private void setupLockingClauseForJoinedExpressions(List joinedExpressions, AbstractSession session) {
        // 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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Related Classes of oracle.toplink.essentials.expressions.Expression

oracle.toplink.essentials.internal.helper.LOBValueWriter

oracle.toplink.essentials.internal.parsing.AggregateNode

oracle.toplink.essentials.internal.parsing.HavingNode

oracle.toplink.essentials.internal.parsing.OrderByItemNode

oracle.toplink.essentials.internal.parsing.SelectGenerationContext

oracle.toplink.essentials.internal.parsing.WhereNode

oracle.toplink.essentials.internal.queryframework.JoinedAttributeManager

oracle.toplink.essentials.mappings.CollectionMapping

oracle.toplink.essentials.mappings.DirectMapMapping

oracle.toplink.essentials.queryframework.UpdateAllQuery

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