How do I make webapi accept POST requests with INPUT?

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I am able to send a post request to a server using:

C#

static async Task SendPost(string jsonMessage)
{
    string url = "https://localhost:44312/GeneratorStatus/PostString";
    HttpClient client = new HttpClient();
    
    var response = await client.PostAsync(url, 
                                          new StringContent("TestMessage",
                                                            Encoding.UTF8,
                                                            "application/json")
                                         );

    Console.WriteLine(response);
}

This is my controller:

C#

[ApiController]
[Route("[controller]")]
public class GeneratorStatusController : ControllerBase
{
    Emails emailList = new Emails();

    [HttpPost("{input}")]
    public void PostString(string input)
    {
        emailList.SendEmail("fromEmail@gmail.com", "1234567890@txt.att.net",
        "Generator Off", input);
    }
}

However, when I run my post request using HttpClient and send a post request to my API Controller, it sends out the request successfully but the message always results in, "PostString" instead of my input variable.

What I have tried:

C#

[ApiController]
[Route("[controller]")]
public class GeneratorStatusController : ControllerBase
{
    Emails emailList = new Emails();

    [HttpPost("{input}")]
    public void PostString(string input)
    {
        emailList.SendEmail("fromEmail@gmail.com", "1234567890@txt.att.net",
        "Generator Off", input);
    }
}

Posted 28-Sep-20 5:37am

stevenlam505

Updated 28-Sep-20 7:38am

v3

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Comments

Oshtri Deka 28-Sep-20 12:12pm

Where is return statement of PostString method?

stevenlam505 28-Sep-20 13:26pm

I had it in the original code and forgot to make it void when I posted the question.

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Richard Deeming · Accepted Answer · 2020-09-28T06:09:00

Quote:

C#

[HttpPost("{input}")]

You've bound the input parameter to the route. Whatever appears in the URL after /GeneratorStatus/ will be the value of your input parameter.

Change your API method to:

C#

[HttpPost]
public void PostString([FromBody] string input)
{
    ...
}

Change the calling code to specify the correct URL, and pass the content correctly:

C#

string url = "https://localhost:44312/GeneratorStatus/";
HttpClient client = new HttpClient();
string input = JsonConvert.SerializeObject(jsonMessage);
var response = await client.PostAsync(url, new StringContent(input, Encoding.UTF8, "application/json"));

NB: If you upload the data as JSON, it needs to be valid JSON. If you want to post a string, it needs to be enclosed in double quotes and properly escaped. Just posting the raw string value won't work.

Model Binding in ASP.NET Core | Microsoft Docs[^]

NB: You should also be using IHttpClientFactory to create the HttpClient instance, otherwise you risk running into problems under load:
Use IHttpClientFactory to implement resilient HTTP requests | Microsoft Docs[^]