FromQuery support in Azure Functions v3

Question

I am trying to use [FromQuery] with Azure Function v3 but I am getting the following error:

Cannot bind parameter 'search' to type String.

For the following method:

[FunctionName("GetObjects")]
public ActionResult<IActionResult> QueryObjects(
    [HttpTrigger(AuthorizationLevel.Function, "GET", Route = "objects")]
    HttpRequest req,
    ILogger log,
    [FromQuery] string search = null)
{
    //do some stuff
}

Is [FromQuery] not supported?

Should I use req.Query["search"] to get the query parameter?

From functions.desp.json

Related to binding

"Microsoft.Extensions.Configuration.Binder/3.1.1": {
    "dependencies": {
        "Microsoft.Extensions.Configuration": "3.1.2"
    },
    "runtime": {
        "lib/netcoreapp3.1/Microsoft.Extensions.Configuration.Binder.dll": {
        "assemblyVersion": "3.1.1.0",
        "fileVersion": "3.100.119.61404"
        }
    }
},

Hi @Sajeetharan I am running this locally I haven´t published the function yet. — doorman, Mar 03 '20 at 17:51
Hi @Sajeetharan I appreciate your help. I have the function.deps.json file but it contains alot of information I am not willing to share I would prefer if you could tell me what you are looking for in the file and I will have a look. Thanks! — doorman, Mar 03 '20 at 21:19
hi, @Sajeetharan the only thing I found related to binding is in the updated question above. But as BowmanZhu states in his answer below, this is probably not supported although it would be nice to have feature. — doorman, Mar 04 '20 at 08:39
No I dont think this is supported so I am currently using req.Query["search"] — doorman, Mar 09 '20 at 06:13
@doorman Hi, if my answer answers your question, can you mark it as the answer to end the question? :) — Cindy Pau, Mar 16 '20 at 14:04
**See Also**: [How to get the GET Query Parameters in a simple way on Azure Functions C#?](https://stackoverflow.com/q/49833056/1366033) — KyleMit, May 17 '21 at 20:40

score 3 · Accepted Answer · answered Mar 04 '20 at 07:07

This is what you face now:

Method signatures developed by the azure function C # class library can include these:

ILogger or TraceWriter for logging (v1 version only)

A CancellationToken parameter for graceful shutdown

Mark input and output bindings by using attribute decoration

Binding expressions parameters to get trigger metadata

From this doc, it seems that it is not supported. You can create your custom binding like this, and dont forget to register it in the startup.

score 3 · Answer 2 · edited May 17 '21 at 18:36

If you want to bind it directly, it's not possible. So you could try to change your route like Function1/name={name}&research={research} then bind it to string parameter.

Below is my test code:

[FunctionName("Function1")]
public static async Task<IActionResult> Run(
    [HttpTrigger(AuthorizationLevel.Function, "get", Route="Function1/name={name}&research={research}")] HttpRequest req,
    String name,
    String research,
    ILogger log)
{
    log.LogInformation("C# HTTP trigger function processed a request.");
    log.LogInformation(research);
    
    string responseMessage = $"Hello, {name}. This HTTP triggered function executed successfully.";

    return new OkObjectResult(responseMessage);
}

FromQuery support in Azure Functions v3

2 Answers2