How to pass empty string to nullable int

Question

I have this property

public int? CodigoBanco { get; set; }

An when i try to send it to server in this way

codigoBanco: ""

I have the following error

The following errors were detected during validation:\r\n - The JSON value could not be converted to System.Nullable`1[System.Int32]

You can't do that. `int?` is not equal to `string`, you might use string for `CodigoBanco` — D-Shih, Apr 19 '22 at 13:08
Or leave the property codigoBanco out of the json or set it to null (`codigoBanco: null`) — Ralf, Apr 19 '22 at 13:15
@D-Shih can i set some convention so the server can handle it and auto convert empty string to null? — Heitor Giacomini, Apr 19 '22 at 13:21
https://stackoverflow.com/questions/52177006/how-to-assign-int-variable-to-empty-in-c — Maytham Fahmi, Apr 19 '22 at 13:36
you need a custom json converter, see [this qa](https://stackoverflow.com/a/57334833). `codigoBanco: ""` is not a valid integer. if you want to pass a null integer properly, you should just skip the property altogether (do not mention it in the json). — Bagus Tesa, Apr 19 '22 at 13:44
@Maytham Since the dafault value for input is an empty string the property is send as codigoBanco: "" . Ralf suggestion worked very well to me. — Heitor Giacomini, Apr 19 '22 at 13:59

score 1 · Answer 1 · answered Apr 19 '22 at 13:29

1

I don't know what's your point of doing that but simple way just casting:

CodigoBanco  =Convert.ToInt32(codigoBanco==""?null:codigoBanco)

the convert returns 0 into your int? property

answered Apr 19 '22 at 13:29

Vali.Pay

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score 1 · Accepted Answer · answered Apr 19 '22 at 14:27

You have two ways to resolve the problem:

Specify null (not empty string) and it will be successfully mapped. codigoBanco: null or remove this property at all from client-side(the default will be the same null)
Write custom convertaion at backend-side, something like:

CodigoBanco = int.Parse(codigoBanco == "" || codigoBanco.Length = 0 ? null : codigoBanco);

score 0 · Answer 3 · answered Apr 19 '22 at 14:03

As @Ralf suggested, I removed all properties with empty string from json. This solved my problem:

function removeEmptyOrNull(obj){
    Object.keys(obj).forEach(k =>
        (obj[k] && typeof obj[k] === 'object') && removeEmptyOrNull(obj[k]) ||
        (!obj[k] && obj[k] !== undefined) && delete obj[k]
    );
    return obj;
};

How to pass empty string to nullable int

3 Answers3

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