Remove default charset from 'application/json' Content-Type header by doortts · Pull Request #2568 · labstack/echo

doortts · 2023-12-28T07:22:02Z

Using application/json; charset=UTF-8 in response header is a common misuse. I think it is better to remove ; charset=UTF-8 from default json response Content-Type header to prevent the misconception.

See: #2567

aldas

You can not just remove/replace echo.MIMEApplicationJSONCharsetUTF8 as it is part of Echos public API and we are quite strict on API changes.

it would be nice if there would be link to JSON spec and remark about charset in doccomment

other than that I think this is probably ok

doortts · 2023-12-29T04:49:58Z

@aldas Thank you for the comment.

I recovered echo.MIMEApplicationJSONCharsetUTF8 and added 'Deprecated: ' comment. Just let let me know if this is not what you intended. https://github.com/labstack/echo/pull/2568/files?diff=unified#diff-aba8ba313c6b989153f1f96e641a8e0e75313485d2e13d64378e70858d5a4669R173
I added a reference link what you mentioned to the issue documentation.
- Related RFC note link
- Related RFC 8.1 Chapter Link

echo.go

Fixes #2567

aldas · 2024-02-06T05:41:55Z

done, Thanks @doortts

washington-guedes · 2024-05-07T18:04:59Z

There are clients outside of what was called "compliant recipient" that got broken, like flutter v2.1 in my case. Is it possible to have a middleware that forces the header Content-Type back to MIMEApplicationJSONCharsetUTF8? @aldas @doortts @nono

aldas · 2024-05-07T18:47:55Z

There are clients outside of what was called "compliant recipient" that got broken, like flutter v2.1 in my case. Is it possible to have a middleware that forces the header Content-Type back to MIMEApplicationJSONCharsetUTF8? @aldas @doortts @nono

Try

	e.GET("/", func(c echo.Context) error {
		c.Response().Header().Set(echo.HeaderContentType, echo.MIMEApplicationJSONCharsetUTF8)
		return c.JSON(http.StatusOK, "HI")
	})

This is how header is written for c.JSON - only when there is no content type header we set it as application/json

echo/context.go

Lines 243 to 248 in 88c379f

    
           func (c *context) writeContentType(value string) { 
        
           	header := c.Response().Header() 
        
           	if header.Get(HeaderContentType) == "" { 
        
           		header.Set(HeaderContentType, value) 
        
           	} 
        
           }

Example

func main() {
	e := echo.New()

	e.GET("/", func(c echo.Context) error {
		c.Response().Header().Set(echo.HeaderContentType, echo.MIMEApplicationJSONCharsetUTF8)
		return c.JSON(http.StatusOK, "HI")
	})

	if err := e.Start(":8080"); err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatal(err)
	}
}

Output:

x@x:~/$ curl -v http://localhost:8080
* processing: http://localhost:8080
*   Trying [::1]:8080...
* Connected to localhost (::1) port 8080
> GET / HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/8.2.1
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Type: application/json; charset=UTF-8
< Date: Tue, 07 May 2024 18:44:09 GMT
< Content-Length: 5
< 
"HI"
* Connection #0 to host localhost left intact

aldas · 2024-05-07T18:53:53Z

or you could create custom json serializer than sets that header before writing the json

package main

import (
	"encoding/json"
	"errors"
	"github.com/labstack/echo/v4"
	"log"
	"net/http"
)

type utf8JSONSerializer struct {
	echo.DefaultJSONSerializer
}

func (d utf8JSONSerializer) Serialize(c echo.Context, i interface{}, indent string) error {
	c.Response().Header().Set(echo.HeaderContentType, echo.MIMEApplicationJSONCharsetUTF8)
	return d.DefaultJSONSerializer.Serialize(c, i, indent)
}

func main() {
	e := echo.New()
	e.JSONSerializer = new(utf8JSONSerializer)

	e.GET("/", func(c echo.Context) error {
		return c.JSON(http.StatusOK, "HI")
	})

	if err := e.Start(":8080"); err != nil && !errors.Is(err, http.ErrServerClosed) {
		log.Fatal(err)
	}
}

The change caused the test to fail: labstack/echo#2568

aldas requested changes Dec 28, 2023

View reviewed changes

aldas requested changes Dec 29, 2023

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Remove default charset from 'application/json' Content-Type header

eae5dc8

Fixes #2567

aldas merged commit 76994d1 into labstack:master Feb 6, 2024

kohkimakimoto added a commit to kohkimakimoto/inertia-echo that referenced this pull request Sep 29, 2024

fix test

c01bdee

The change caused the test to fail: labstack/echo#2568

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Remove default charset from 'application/json' Content-Type header#2568

Remove default charset from 'application/json' Content-Type header#2568
aldas merged 1 commit intolabstack:masterfrom
doortts:default-json-encoding

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