Basic lookups and referenced field lookups

In the dynamics ax 2012, there are different ways to fill the combo box/drop down list

How to create a simple lookup

The SysTableLookup class is provided by the standard application to allow programmers to easily create their own lookup forms, in code.

The basic steps to using this class are as follows:

1. Create the sysTableLookup object
2. Create the query to select the lookup data
3. Add  the fields shown on the lookup
4. Performs the lookup

client static void lookup<TableName> (FormStringControl _ctrl) {     SysTableLookup          sysTableLookup       =  SysTableLookup::newParameters(tableNum(<tableName>),_ctrl);     Query                   query                = new Query();     // create the query for the lookup     QueryBuildDataSource    queryBuildDataSource = query.addDataSource(tableNum(<tableName>));     // Add fields that will be shown in the lookup as columns             sysTableLookup.addLookupfield(fieldNum(<tableName>,<FeildName1>));     sysTableLookup.addLookupfield(fieldNum(<tableName>,<FeildName2>));     //Add the query to the lookup form     sysTableLookup.parmQuery(query);     // Perform the lookup     sysTableLookup.performFormLookup(); }

How to create a simple lookup Reference

 

 The SysReferenceTableLookup class is used to construct lookup forms for reference controls.

1. Create the SysReferenceTableLookup object
2. Create the query which will be used to select the lookup data
3. Add the fields which will be shown on the lookup
4. Perform the lookup 

This method is now the standard method used to lookup the data for drop down when there is any modification needed to override the behavior of the functionality provided by the automatic lookup

public static client <tableName> lookup<tableName>(     FormReferenceControl        _formReferenceControl) {     Query                   query;     SysReferenceTableLookup referenceLookup;     if (_formReferenceControl == null)     {         throw error(Error::missingParameter(null));     }     referenceLookup = SysReferenceTableLookup::newParameters(         tableNum(<tableName>),         _formReferenceControl,         true);     // create the query for the lookup form      query.addDataSource(tableNum(<tableName>));     // Add fields that will be shown in the lookup form as columns     referenceLookup.addLookupfield(fieldNum(<tableName>,<FeildName1>));     referenceLookup.addLookupfield(fieldNum(<tableName>,<FeildName2>));     // Add the query to the lookup form     referenceLookup.parmQuery(query);     // Perform the lookup and return the selected record     return referenceLookup.performFormLookup() as <tableName>; }