Multi Select Look up in Class level in X++

                                 Multi Select Look Up in Class

class Nar_productvarientsDialog extends Runbase
{

    DialogRunbase                dialog;
    DialogGroup                 dialogGrp;

    FormBuildStringControl      fbsCtrlPromotion;
    FormStringControl           fsCtrlPromotion;
    container                   returnPromotion;
    SysLookupMultiSelectCtrl    msCtrlPromotion;
    str                         promotionRange;
}
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public query buildQuery()
{
    Query                   q          = new Query();
    QueryBuildDataSource    qbds;
    InventTable             inventTable;

    ;
    qbds    = q.addDataSource(tablenum(InventTable));
    qbds.addSelectionField(fieldNum(InventTable,ItemId));
    while select inventTable
    {
        qbds.addRange(fieldNum(InventTable,ItemId)).value(inventTable.ItemId);
    }
    return q;

}

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protected Object dialog()

{

    FormBuildControl    setupGroupControl;

    ;

    dialog = super();

    dialog.alwaysOnTop(true);

    dialog.windowType(FormWindowType::Standard);

    dialogGrp = dialog.addGroup('Promotion');

    setupGroupControl = dialog.formBuildDesign().control(dialogGrp.formBuildGroup().id());

    fbsCtrlPromotion = setupGroupControl.addControl(FormControlType::String, identifierstr(DICPromotionID));

    fbsCtrlPromotion.label('Promotion id');

    dialog.allowUpdateOnSelectCtrl(true);

    this.dialogSelectCtrl();

    return dialog;

}

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public void dialogPostRun(DialogRunbase _dialog)

{

    FormRun formRun;

    super(dialog);

    formRun = _dialog.dialogForm().formRun();

    if (formRun)

    {

        fsCtrlPromotion = formRun.design().control(fbsCtrlPromotion.id());

        /// you can build with your own query, or created query in system by method construct

        msCtrlPromotion = SysLookupMultiSelectCtrl::constructWithQuery(formRun, fsCtrlPromotion, this.buildQuery());

    }

}

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public boolean getFromDialog()

{

    boolean         ret;

    #Characters

    ret = super();

    if (msCtrlPromotion)

    {

        returnPromotion = msCtrlPromotion.getSelectedFieldValues(); // get actual value of the selected rows

        //returnPeriodRecId = msCtrlPromotion.get();  // get RecIds of the selected rows  (it's very useful when you want to look one field and return another field value)

    }

    promotionRange    = con2StrUnlimited(returnPromotion,#comma);

    return ret;

}

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public static void main(Args _args)

{

    Nar_productvarientsDialog           nar_productvarientsDialog;

    nar_productvarientsDialog   = new Nar_productvarientsDialog();

    if(nar_productvarientsDialog.prompt())

    {

      nar_productvarientsDialog.run();

    }

}