Validation on query string parameters of .Net Core Action Method

Question

I have a .Net Core 2.2 Web API. One of my controller action methods takes two query string parameter, a year and a month.

GET: /api/ItemsForMonth?year=2019&month=8

The action method looks like this:

[HttpGet]
public async Task<ActionResult<IEnumerable<Item>>> GetItemsForMonth([FromQuery] int year, [FromQuery] int month)
{
    if (year <= 2000 || month <= 0 || month > 13)
        return BadRequest("Please check the year and month parameters.");
}

So I am checking to make sure that the year is greater than 2000, and the month is between 1 and 12.

Is that the best way of doing it? I know if the parameters were part of the route instead of query strings (and maybe they should be?) I could do this

GET: /api/ItemsForMonth/2019/8

[HttpGet("/{year:int:min(2000)}/{month:int:min(1):max(12)}")]
public async Task<ActionResult<IEnumerable<Item>>> GetItemsForMonth()
{
}

But is there something similar for query string parameters?

Thanks

Jota.Toledo · Accepted Answer · 2019-09-05 13:17:18Z

16

One approach would be to bind the query parameters into a model and use basic attribute-based model validation:

class DateQueryParameters {
  [Required]
  [Range(2000, int.MaxValue)]
  public int Year {get;set;}

  [Required]
  [Range(1, 12)]
  public int Month {get;set;}
}

[HttpGet]
public async Task<IActionResult> GetItemsForMonth([FromQuery] DateQueryParameters dateParameters)
{
    if(!this.ModelState.IsValid){
       return Task.FromResult(this.BadRequest(this.ModelState));
    }
}

Model validation will be done automatically if your controller is decorated with the ApiController attribute.

edited Sep 5, 2019 at 13:17

answered Sep 5, 2019 at 13:11

Jota.Toledo

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3 Comments

Fabricio Rodriguez Over a year ago

Excellent suggestion. Thanks Jota.

anhtv13 Over a year ago

Hi @Jota.Toledo, how can I disable the automatic validation of ApiController? I post an invalid object to my endpoint but the thing is the automatic validation has done before the code can go to my method.

Marcoscdoni Over a year ago

Unfortunately net core 6 minimal API doesn't provide automatic mapping of querystring data to a complex object. This is something I'm missing a lot

Sunny Sharma · Accepted Answer · 2021-07-27 09:57:08Z

1

yes, now there is. Refer to the following docs page: https://learn.microsoft.com/en-us/aspnet/web-api/overview/web-api-routing-and-actions/attribute-routing-in-web-api-2#route-constraints

here's the sample code:

[HttpGet("/{year:int:min(2000)}/{month:int:min(1):max(12)}/{query:maxlength(15)}")]
public async Task<ActionResult<IEnumerable<Item>>> GetItemsForMonth()
{
}

notice the "/{query:maxlength(15)}" in the end of the route params list.

edited Jul 27, 2021 at 9:57

answered Jul 27, 2021 at 9:46

Sunny Sharma

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2 Comments

Oleksii Zhyglov Over a year ago

Those are not query string parameters. The question was about them.

Abhi Over a year ago

Here, year and month are still part of url and not query string.

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