Mark Date field as Nullable in .cds file for CAPM project

[raavi]

Dear Colleagues,
I am building a CAPM project where I have Date type(type: Date or Timestamp) field in my cds. I want this field to be Nullable because whenever I try to save the UI with null values it throws error as below

Deserialization Error: Invalid Value Z(String) for property..... 

Since, Date field is optional I would like to mark it as Nullable so that error is no shown while creating the records.

Kindly Help.

#capm #cds

[RalfHandl]

Apparently your UI sends "OnStockDate":"Z" to the backend if the input field is empty instead of sending "OnStockDate":null.

[raavi]

Dear @RalfHandl,

[raavi]

Dear @RalfHandl, I checked the UI, and it is not sending 'Z' as value. In network I can see payload as "OnStockDate": ""

[RalfHandl]

Well, "OnStockDate":"" is as wrong as "OnStockDate":"Z" would be. The UI must send "OnStockDate":null if the date should be null.

[raavi]

Dear @RalfHandl, Since on UI since I am not entering any value in the date input field, so it is expected that it will take the blank value, and in the payload I can see the blank value. However framework throws error with blank value. How and Why will the UI pass null ?

[RalfHandl]

How to make the UI pass null depends on the UI techonology you are using. Please add this information to your question.

[raavi]

No, what I mean is, why is it expecting me pass a null value? Can't I simply keep the Date field as blank ?

[raavi]

What I believe is in Odata we have an option to add a nullable property to our Date fields, if we want to keep it blank, however I see that option is not available here. Is it possible to mark Date field as Nullable so that it accepts blank values as well ?

[raavi]

Dear @RalfHandl, Is it necessary to pass null for Date field, is it not possible to add annotation in CDS so that it will accept blank/empty values?

[RalfHandl]

If you define an element in CAP CDS without the "not null" phrase, it is nullable. Which means it will accept JSON null as a value, which is different from an empty JSON string. There is no magic switch to treat empty strings identical to null.

[raavi]

@RalfHandl, but I also have fields of type String and Integer which are defined with Not Null Phrase, but when empty Json string is accepted here, but same is not true Date field. I am using SAPUI5 as frontend, and I think it is giving empty strings as default for input fields

[RalfHandl]

An empty string is a string and it is not null.

An "empty" integer typically is zero which again is different from null.

Unfortunately I don't know how to tell SAPUI5 to treat an empty date field as null.