Render JSON with custom Content-Type in Gin

Question

I want to know if it is possible to add a "method" to Gin's context to add the header Content-Type: application/hal+json instead of doing it in all API calls SetHeader.

Something like this:

ctx.HALJSON(http.StatusOK, hal)

Answer 1

You can use c.Render with a custom renderer, that implements render.Renderer.

If the actual rendering is identical to JSON (HAL should be) you can embed render.JSON into your struct, so that the method Render(http.ResponseWriter) error comes for free, and then implement only the custom content type:

type HALJSON struct {
    render.JSON
}

func (HALJSON) WriteContentType(w http.ResponseWriter) {
    header := w.Header()
    if val := header["Content-Type"]; len(val) == 0 {
        header["Content-Type"] = []string{"application/hal+json"}
    }
}

And then use it as such:

func MyHandler(c *gin.Context) {
    // handler code...
    c.Render(http.StatusOK, HALJSON{})
}