NESTEDSESSION operator

The NESTEDSESSION operator creates an action that executes the other action in a nested session.

Syntax

NESTEDSESSION action 

Description

The NESTEDSESSION operator creates an action which executes the other action in a nested session. With that, all changes that have already been made in the current session get into the created nested session. Also, all changes that are made in the nested session will get into the current session when the changes are applied in the nested session.

Parameters

• action

  A context-dependent action operator that defines an action to be executed in the nested session.

Examples

testNestedSession ()  {
    NESTEDSESSION {
        name(Sku s) <- 'aaa';
        // in fact, the changes will not be applied to the database, but to the "upper" session
        APPLY; 
    }

    MESSAGE (GROUP SUM 1 IF name(Sku s) == 'aaa'); // returns all rows
    CANCEL;
    // returns NULL if there was no Sku named aaa in the database before
    MESSAGE (GROUP SUM 1 IF name(Sku s) == 'aaa'); 

}

FORM sku
    OBJECTS s = Sku PANEL
    PROPERTIES(s) id, name
;
newNestedSession()  {
    NESTEDSESSION {
        NEW s = Sku {
            // shows the form, but any changes in it will not be applied to the database, 
            // but will be saved in the "upper session" session
            SHOW sku OBJECTS s = s;
        }
    }
}