.net 7 Route Handling and Parameter Binding in minimal apis

Question

I had asked this question on Regex parsing with multiple named groups. This is the original problem that motivated that question and is an orthogonal problem.

In .net 7, using the minimal apis is there a way to map multiple key-value pairs that appear in the url query parameters? The documentation in the previous link gives examples of binding a single parameter to the url fragment or slug. How do we map multiple key-value pairs?

The asp.net core documentation provides the following example:

app.MapGet("/{id}", (int id,
                     int page,
                     [FromHeader(Name = "X-CUSTOM-HEADER")] string customHeader,
                     Service service) => { });

where

id is mapped to the path parameter,
page is mapped to the query parameter,
customHeader is mapped to a header field,
service is provided by dependency injection

My Example URL is: /o/post?id=123&filter=xyz

Does .net 7 asp.net core provide a way to map the id and filter parameters to a handler automatically or should I use

app.MapGet("/o/{*rest}", (string rest) => $"Routing to {rest}");

and handle the parsing myself?

I am thinking there should be a simpler way than handling the parsing myself. Is there one?

No. This is a single route and a handler for that. The `/o/?` is the general pattern of the route. In the backend, this constructs a query to a table for `` using a filter criteria derived from the ``. — vvg, Jan 27 '23 at 08:10
@vernou, coming to think of it, `/o/post?id=123&filter=xyz` and `/o/comment?id=1001` are examples of routes that get handled by the same handler. So, the answer to your question is Yes. I meant that the same handler handles the logic for all object type queries. — vvg, Jan 27 '23 at 08:13

score 1 · Accepted Answer · answered Jan 27 '23 at 08:29

After reading your comment, yes this is easily possible with minimal APIs. What you have to do is to pass the HttpRequest and access the query of that request.

I would do something like this.

app.MapGet("/{type}", (string type,
                 HttpRequest request) =>
                 {
                     return new { Type = type, queryParams = request.Query};
                 }); ;

if you now call your endpoint like this /comment?userID=21546&commentID=76165 you will get this result:

{
    "type": "comment",
    "queryParams": [
        {
            "key": "userID",
            "value": [
                "21546"
            ]
        },
        {
            "key": "commentID",
            "value": [
                "76165"
            ]
        }
    ]
}

If you call this URL /post?postID=76165 you will get this response. As you can see only the sent query parameters are available.

{
    "type": "post",
    "queryParams": [
        {
            "key": "postID",
            "value": [
                "76165"
            ]
        }
    ]
}

You can then build a switch case based on the type string and do whatever logic you need. Hope this puts you in the right direction.

.net 7 Route Handling and Parameter Binding in minimal apis

1 Answers1