1 Reply Latest reply on Oct 30, 2017 8:46 AM by shawkins

how to change the value of a where clause exprssion in createResultSetExecution

mkamran Oct 30, 2017 4:31 AM

Hi Everyone,

Using teiid-9.1.1 , i am writing a translator, in createResultSetExecution need to change the value of where clause in select command.

like below

select * from table where table_name='test-01';

i need to chagne the value of test-01 to test before executing the request.

Thanks in advance for any help.

Kamran

1. Re: how to change the value of a where clause exprssion in createResultSetExecution

shawkins Oct 30, 2017 8:46 AM (in response to mkamran)

Your logic to do this will depend upon a few factors, such as what types of commands you can handle (just Select or also SetQuery), what predicates are allowed, etc. Navigating directly looks like:

Select select = (Select)command;
Condition condition = select.getWhere();
if (condition instanceof Comparison) {
Comparison comparison = (Comparison)condition;
Expression lex = comparison.getLeftExpression();
if (lex instanceof ColumnReference) {
   //further test that it's the column reference you want

   //set the right to a new literal
   comparison.setRightExpression(new Literal("new value", String.class));
}
}

You may also use a visitor:

HierarchyVisitor visitor = new HierarchyVisitor() {
    public void visit(Comparison obj) {
        //do something here
    }
};

Select select = (Select)command;
Condition condition = select.getWhere();
if (condition != null) {
condition.acceptVisitor(visitor);
}

Finally you may also want to consider if there is a way to do this type of manipulation using a standard mechanism, such as row level data role conditions.
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