nested model not binding when sending data using postman

Question

Object reference error getting when I'm trying to put data using WebAPI2. My class structure is like this

public class Student
{
    public int Id { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
    public Address address { get; set; }
}

public class Address
{
    public int Id { get; set; }
    public int StudentId { get; set; }
    public string City { get; set; }
    public string AddressLine { get; set; }
}

My Put method is like below

public async Task putStudentProfile(Student student)
{
    tblStudent std= db.tblStudent .FirstOrDefault(p => p.ID == student.Id);
    std.NAME = student.Name;
    std.EMAIL= student.Email;
    tblAddress addr= db.tblAddress.FirstOrDefault(q => q.ID == student.Id);
    addr.City= student.address.City;
    await db.SaveChangesAsync();
}

Sending JSON data using postmen. My JSON data is like this

{
"Id":59,
"Name": "Sandeep",
"Email": "xxxxxxxx@xxxx.com",
"address":{
    "Id":42,
    "StudentId": "59",
    "City": "xxxxxx",
    "AddressLine":"xxxxxxxxxxxxx"
    }
}

I'm getting object reference error when I try to access student.address.City

Any idea to solve this?

@StephenMuecke Thanks for your comment, i'm sending data from the postmen. How can i initialized address property of student? any advice? — sandeep nagabhairava, Dec 20 '15 at 07:14
If your sending the data correctly, then the `DefaultModelBinder` will initialize and bind the `address` property. You need to edit your question showing how you send the data to the controller (and then I will reopen the question) — , Dec 20 '15 at 07:17
Change it to `"address.Id": 42`, `"address.StudentId": "59"` etc (remove the `"address":{ ... }`) — , Dec 20 '15 at 07:38

score 2 · Answer 1 · 2016-07-18T04:22:03.540

2

The format of the javascript object is incorrect and needs to be in dot notation (the same way you would access the values of the property in the controller)

{
    "Id":59,
    "Name": "Sandeep",
    "Email": "xxxxxxxx@xxxx.com",
    "address.Id": 42,
    "address.StudentId": 59,
    "address.City": "xxxxxx",
    "address.AddressLine": "xxxxxxxxxxxxx"
}

edited Jul 18 '16 at 04:22

answered Dec 20 '15 at 08:02

Since it is not really valid JSON representation of object would you mind to add link that explains this behavior? – Alexei Levenkov Dec 20 '15 at 08:03
@AlexeiLevenkov, Because the default for postman is `x-www-form-urlencoded`, the `DefaultModelBinder` needs it in this format. Otherwise it would need to be stringified (e.g. `JSON.stringify()` and the `contentType` set to `'json'` - but I'm not familiar enough with postman to know if that can be done (will do a bit of extra research later) – Dec 20 '15 at 08:11

nested model not binding when sending data using postman

1 Answers1