Creating lookup control in D365

The easiest way to do lookup on your form control in D365 can be achieved by following the steps mentioned below.

1. Go to your field where lookup needs to be created 
2. Expand the Events node of form control
3. Right click OnLookup event and select "Copy event handler method"
   
4. Create a new class and name it appropriately (Naming convention "FormName"+"EventHandler")
5. In newly created class press Ctrl + V

          [FormControlEventHandler(formControlStr(SalesTable, LC_AssetGroup_LC_AssetId), FormControlEventType::Lookup)]

    public static void LC_AssetGroup_LC_AssetId_OnLookup(FormControl sender, FormControlEventArgs e)

    {

        

    }

Do your lookup code inside the handler, as shown below

FormControlEventHandler(formControlStr(SalesTable, LC_AssetGroup_LC_AssetId), FormControlEventType::Lookup)]

public static void LC_AssetGroup_LC_AssetId_OnLookup(FormControl sender, FormControlEventArgs e)

{

    Query                   query = new Query();

    QueryBuildDataSource    queryBuildDataSource;

    SysTableLookup          sysTableLookup;

    sysTableLookup = SysTableLookup::newParameters(tableNum(AssetBook), sender);

    queryBuildDataSource = query.addDataSource(tableNum(AssetBook));

    queryBuildDataSource.addRange(fieldNum(AssetBook, Status)).value(strFmt('((Status == %1) || (Status == %2))', any2int(AssetStatus::Open), any2int(AssetStatus::Closed)));

    sysTableLookup.addLookupField(fieldNum(AssetBook, AssetId), true);

    sysTableLookup.addLookupMethod(tableMethodStr(AssetBook, assetName));

    sysTableLookup.parmQuery(query);

    sysTableLookup.performFormLookup();

}

Output