Array of objects not getting detected in Web API

Question

I am developing a Web API with .NET Core 2.1 where the response is manipulated based on the output received from a WCF service.

I need to have a API with Get verb and need to pass an array of complex objects as the input to it.The challenge currently I am facing is, the array is not getting detected from the input.I have added [FromQuery] along with the input parameter. I am trying the same from Swagger UI.

Tried adding Name along with FromQuery .

[HttpGet("test")]
public IActionResult Testmethod([FromQuery] Person person)
{
    return Ok(person);
}

Model classes:

public class Person
{
    public string Name{ get; set; }
    public int Age{ get; set; }
    public Grade[] grades{ get; set; }
}

public class Grade
{
    public int GradeId { get; set; }
    public string GradeName { get; set; }
    public string Section { get; set; }
}

There is no array of object here? How are you calling the API? What is the URL you use? Also, please take more care in your posts and format them correctly next time. — DavidG
– DavidG, Commented May 31, 2019 at 13:11
Why you are not using POST instead, your model is getting pretty complex... You want to give all that information through an URL that has a length of 2000 characters?! — Sinan
– Sinan, Commented May 31, 2019 at 13:28

harvzor · Accepted Answer · 2021-08-16 09:44:47Z

It seems that Swagger generates the query a little bit wrong for this case. The correct query is:

GET /test
  ?name=thomas
  &age=20
  &grade[0].gradeId=2
  &grade[0].gradeName=Second
  &grade[0].section=Section

External resources

This issue has been documented here: https://github.com/domaindrivendev/Swashbuckle.AspNetCore/issues/1832

Also talked about here: OpenAPI query string parameter with list of objects

Solution

This is an issue with OpenAPI and we can not solve it.

This is the best solution:

If you are designing a new API (rather than describing an existing one), consider passing the array of objects in the request body instead.

https://stackoverflow.com/a/52894157

Query string format is different depending on the object

This is unusual because if the code was like this:

[HttpGet("test")]
public IActionResult Testmethod([FromQuery] SomeQuery query)
{
    // ...
}

public class SomeQuery
{
    public int[] Ids { get; set; }
}

Our API call will look like:

GET /test
  ?ids=1
  &ids=2

However, if you have an array of objects, then the format of the GET request changes.

Versions tested with

Swashbuckle.AspNetCore 6.5.0
.NET Framework net5.0

Hakit01 · Accepted Answer · 2019-05-31 13:17:31Z

-2

Try the below

[FromBody] IEnumerable<Person> persons

answered May 31, 2019 at 13:17

Hakit01

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2 Comments

DavidG Over a year ago

From the question I need to have a API with Get verb. Also, what makes you think OP needs an enumerable of Person?

ams16 Over a year ago

The issue is with Grade[] object.Its coming as null in the request,Not the Person..

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