How to implement endpoints for specific content-types

[eloo]

Issue Description

How to implement endpoints for specific content-types

Checklist

• Dependencies installed
• No typos
• Searched existing issues and docs

Expected behaviour

I've have an PATCH endpoint which only accepts requests with content-type application/merge-patch+json

Actual behaviour

Not sure how to implement it

Details

I'm currently trying to create an endpoint which supports the https://tools.ietf.org/html/rfc7396 standard for patching resources.
But im struggling right now how to implement the specific content-type i want to accept.
So every request without the content-type to be set to application/merge-patch+json should be rejected with at 415.

My two ideas are the following:

• In the handler function i just check the header manually and reject it with 415 if the content-type does not match
  or what i've found here so far
• Create custom binder to bind the data which only accepts the specific content-type

I guess the second approach is the better but i'm not sure if there is maybe another solution or what should be prefered?

Thanks

[mymtw]

think that you should check both

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[eloo]

for the record:
i'm now using the following snippet for this use-case:

import (
	"encoding/json"
	"fmt"
	"net/http"
	"strings"

	"github.com/labstack/echo/v4"
)

type MergeJsonBinder struct{}

// Bind implements the `Binder#Bind` function.
func (b *MergeJsonBinder) Bind(i interface{}, c echo.Context) (err error) {
	req := c.Request()

	names := c.ParamNames()
	values := c.ParamValues()
	params := map[string][]string{}
	for i, name := range names {
		params[name] = []string{values[i]}
	}
	if req.ContentLength == 0 {
		return
	}
	ctype := req.Header.Get(echo.HeaderContentType)
	switch {
	case strings.HasPrefix(ctype, MIMEApplicationMergePatchJSON):
		if err = json.NewDecoder(req.Body).Decode(i); err != nil {
			if ute, ok := err.(*json.UnmarshalTypeError); ok {
				return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Unmarshal type error: expected=%v, got=%v, field=%v, offset=%v", ute.Type, ute.Value, ute.Field, ute.Offset)).SetInternal(err)
			} else if se, ok := err.(*json.SyntaxError); ok {
				return echo.NewHTTPError(http.StatusBadRequest, fmt.Sprintf("Syntax error: offset=%v, error=%v", se.Offset, se.Error())).SetInternal(err)
			}
			return echo.NewHTTPError(http.StatusBadRequest, err.Error()).SetInternal(err)
		}
	default:
		return echo.ErrUnsupportedMediaType
	}
	return
}

and something like this in the endpoint handler

mergeJsonBinder := MergeJsonBinder{}
		var body map[string]interface{}
		err := mergeJsonBinder.Bind(&body, c)
		if err != nil {
			return err
		}

maybe this can be adapted and added as an example to the documention?

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[lyda]

I submitted PR #2572 which would fix this issue.

[vishr]

This has been answered above and is labeled wontfix. Closing to tidy the tracker — thanks all for the discussion. 🙏