I need to write a sting in a form field, but I get an error message "object is ReadOnly" - "Objekt ist schreibgeschützt"

&AtClient
Procedure CashDiscountOnChange(Item)
   If Object.CashDiscount < 0 Then
       Items.CashDiscountText.ReadOnly = False;
       Items.CashDiscountText = "minus " + Object.CashDiscount*-1 + " % ";
   EndIf;   
EndProcedure

Hey Lioudmila! is CashDiscountText a form attribute? If it is, you can set it directly by doing:

CashDiscountText = "minus " + Object.CashDiscount*-1 + " % ";

Hi Bernard,

Thank you for your reply. Yes, it is a document form attribute. But it also doesn't work this way. In this case I don't get any error, but the field is not changed.

If your field is a decoration without reference to the object attribute, use the following script:

Items.CashDiscountText.Title = "minus " + Object.CashDiscount*-1 + " % "

Thanks, Sergey! But in this case nothing happens. No error, but the attribute is not changed.

I have found it out! I deleted data attribute and (Bernard, you were right!) created a textfield with data path CashDiscountText1.

&AtClient
Procedure CashDiscount1OnChange(Item)
   If Object.CashDiscount1 < 0 Then
       CashDiscountText1 = "abzüglich " + Object.CashDiscount1*-1 + " % " + "nachlass";
       
   EndIf;   
EndProcedure

Please note that strings that are displayed to user should be localized, so use NStr function for that. Also for substitution into string for localization reasons please use function of 1C:Subsystems Library, here is an example:

MessageText = NStr("en = 'Failed to generate the %1 on the base of %2.'");
MessageText = StringFunctionsClientServer.SubstituteParametersInString(MessageText,
                       Metadata.FindByType(TypeOf(Ref)).Presentation(), String(Value));