Below handler handles GET
request, without populating http Response
header:
// ListAll handles GET requests and returns all current products
func (p *ProductHandler) ListAll(rw http.ResponseWriter, r *http.Request) {
p.l.Println("[DEBUG] get all records")
prods := data.GetProducts()
err := data.ToJSON(prods, rw)
if err != nil {
// we should never be here but log the error just incase
p.l.Println("[ERROR] serializing product", err)
}
}
Below handler handles GET
request, populating http Response
header:
// ListAll handles GET requests and returns all current products
func (p *ProductHandler) ListAll(rw http.ResponseWriter, r *http.Request) {
p.l.Println("[DEBUG] get all records")
rw.Header().Add("Content-Type", "application/json")
prods := data.GetProducts()
err := data.ToJSON(prods, rw)
if err != nil {
// we should never be here but log the error just incase
p.l.Println("[ERROR] serializing product", err)
}
}
Both cases are working fine with simple curl request.
For any http client,
When do we need to populate content-type
header, before sending the response, to client?
Always read the documentation first!
The answer to this is clearly covered here (emphasis obviously added):
// If WriteHeader has not yet been called, Write calls
// WriteHeader(http.StatusOK) before writing the data. If the Header
// does not contain a Content-Type line, Write adds a Content-Type set
// to the result of passing the initial 512 bytes of written data to
// DetectContentType. Additionally, if the total size of all written
// data is under a few KB and there are no Flush calls, the
// Content-Length header is added automatically.
To explicitly answer your secondary question:
When do we need to populate
content-type
header?
Any time you don't want it to be automatically detected. Automatic detection is imprecise, so you generally don't want to rely on it.
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