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lookup() - Form data source field methods in D365 F&O - X++ Code

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Answer with Explanation

The lookup() method is a standard method on the field of the form data source. This method is called when a lookup operation is attempted on a data source field. If data that's shown in the lookup form must be customized with some filter, the lookup() method should be overridden.

Example

You have a custom form with a table named TrainingMaster. The table has a field named TrainerID that creates a foreign key with the TrainerTable. TrainerTable has an enum field called TrainerType that has two values: Technical and Functional. The lookup in the TrainerID field should display only technical trainers.

The coding pattern can be as follows:


[DataSource]
class TrainingMaster
    {
        [DataField]
        class TrainerID 
        {
            public void lookup(FormControl _formControl, str _filterStr)
            {
                SysTableLookup sysTableLookup = 
                   SysTableLookup::newParameters(tableNum(TrainerTable),_formControl);
                
                Query query = new Query();
                QueryBuildDataSource qbds;
                qbds= query.addDataSource(tableNum(TrainerTable));
                qbds.addRange(fieldNum(TrainerTable, 
                     TrainerType)).value(enum2Str(TrainerType::Technical));

                sysTableLookup.addLookupfield(fieldNum(TrainerTable,TrainerID));
                sysTableLookup.addLookupfield(fieldNum(TrainerTable,TrainerName));

                sysTableLookup.parmQuery(query);
                sysTableLookup.performFormLookup();
            }
        }
    }