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.

        //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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    protected void initializeSelectionCriteria(AbstractSession session) {
        if (this.getSourceToTargetKeyFields().isEmpty()) {
            throw DescriptorException.noForeignKeysAreSpecified(this);
        }


        Expression criteria;
        Expression builder = new ExpressionBuilder();
        Iterator keyIterator = getSourceToTargetKeyFields().keySet().iterator();
        while (keyIterator.hasNext()) {
            DatabaseField foreignKey = (DatabaseField)keyIterator.next();
            DatabaseField targetKey = (DatabaseField)getSourceToTargetKeyFields().get(foreignKey);


            Expression expression = builder.getField(targetKey).equal(builder.getParameter(foreignKey));
            criteria = expression.and(getSelectionCriteria());
            setSelectionCriteria(criteria);
        }
    }

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     */
    protected void initializePrivateOwnedCriteria() {
        if (!isForeignKeyRelationship()) {
            setPrivateOwnedCriteria(getSelectionCriteria());
        } else {
            Expression pkCriteria = getDescriptor().getObjectBuilder().getPrimaryKeyExpression();
            ExpressionBuilder builder = new ExpressionBuilder();
            Expression backRef = builder.getManualQueryKey(getAttributeName() + "-back-ref", getDescriptor());
            Expression newPKCriteria = pkCriteria.rebuildOn(backRef);
            Expression twistedSelection = backRef.twist(getSelectionCriteria(), builder);
            if (getDescriptor().getQueryManager().getAdditionalJoinExpression() != null) {
                // We don't have to twist the additional join because it's all against the same node, which is our base
                // but we do have to rebuild it onto the manual query key
                Expression rebuiltAdditional = getDescriptor().getQueryManager().getAdditionalJoinExpression().rebuildOn(backRef);
                if (twistedSelection == null) {
                    twistedSelection = rebuiltAdditional;
                } else {
                    twistedSelection = twistedSelection.and(rebuiltAdditional);
                }

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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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                }
                // ignore the first token since we are assuming read all query
                // e.g. In e.phoneNumbers we will assume "e" refers to the base of the query
                String previousToken = tokenizer.nextToken();
                ClassDescriptor descriptor = olrq.getDescriptor();
                Expression expression = olrq.getExpressionBuilder();
                while (tokenizer.hasMoreTokens()){
                    String token = tokenizer.nextToken();
                    ForeignReferenceMapping frMapping = null;
                    DatabaseMapping mapping = descriptor.getObjectBuilder().getMappingForAttributeName(token);
                    if (mapping == null){
                        throw QueryException.queryHintNavigatedNonExistantRelationship(query, QueryHints.LEFT_FETCH, valueToApply, previousToken + "." + token);
                    } else if (!mapping.isForeignReferenceMapping()){
                        throw QueryException.queryHintNavigatedIllegalRelationship(query, QueryHints.LEFT_FETCH, valueToApply, previousToken + "." + token);
                    } else {
                        frMapping = (ForeignReferenceMapping)mapping;
                    }
                    descriptor = frMapping.getReferenceDescriptor();
                    if (frMapping.isCollectionMapping()){
                        expression = expression.anyOfAllowingNone(token);
                    } else {
                        expression = expression.getAllowingNull(token);
                    }
                    previousToken = token;
                }
                olrq.addJoinedAttribute(expression);
            } else {

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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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            expression.addChild(Expression.from(null, geom1));
        }else{
            expression.addChild(Expression.from(params, geom1));
        }
        expression.setOperator(anOperator);
        Expression finalExpression = expression.equal("TRUE");
        return finalExpression;
    }

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                DatabaseField field = (DatabaseField)fieldsForTable.elementAt(i);
                writer.write(field.getName());
                writer.write(" = ");
                if(values.elementAt(i) instanceof Expression) {
                    // the value in the modify row is an expression - assign it.
                    Expression exp = (Expression)values.elementAt(i);
                    if(printer == null) {
                        printer = new ExpressionSQLPrinter(session, getTranslationRow(), call, false, getBuilder());
                        printer.setWriter(writer);
                    }
                    printer.printExpression(exp);

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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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     */
    protected ReadObjectQuery getQuery() {
        if (m_query == null) {
            m_query = new ReadObjectQuery(m_parentClass);
            
            Expression selectionCriteria = null;
            Iterator keys = m_queryKeyFields.keySet().iterator();
            ExpressionBuilder builder = new ExpressionBuilder();
            
            while (keys.hasNext()) {
                String keyField = ((DatabaseField) keys.next()).getQualifiedName();
                
                if (selectionCriteria == null) {
                    selectionCriteria = builder.getField(keyField).equal(builder.getParameter(keyField));
                } else {
                    selectionCriteria.and(builder.getField(keyField).equal(builder.getParameter(keyField)));
                }
                
                m_query.addArgument(keyField);
            }

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