54 lines
1.7 KiB
Go
54 lines
1.7 KiB
Go
package api
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import (
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"encoding/json"
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"net/http"
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)
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// Error responses always use this envelope:
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//
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// {"error": {"code": "...", "message": "..."}}
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//
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// Known codes: invalid_json, validation_failed, not_found, invalid_id,
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// method_not_allowed, internal_error, timeout, unavailable. Add new codes
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// here when needed.
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type errorResponse struct {
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Error errorDetail `json:"error"`
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}
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type errorDetail struct {
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Code string `json:"code"`
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Message string `json:"message"`
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}
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// maxBodySize caps JSON request bodies at 1 MiB.
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const maxBodySize = 1 << 20
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// writeJSON sets the content type and encodes v.
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func writeJSON(w http.ResponseWriter, status int, v any) {
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w.Header().Set("Content-Type", "application/json; charset=utf-8")
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w.WriteHeader(status)
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// The status line is already sent, so an encode failure can only be
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// logged — and only by wrapping the ResponseWriter. Not worth it here.
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_ = json.NewEncoder(w).Encode(v)
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}
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// writeError emits the error envelope with the given status and code.
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func writeError(w http.ResponseWriter, status int, code, message string) {
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writeJSON(w, status, errorResponse{Error: errorDetail{Code: code, Message: message}})
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}
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// decodeJSON strictly decodes the request body into dst: unknown fields and
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// bodies over maxBodySize are rejected. It writes the 400 response itself
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// and returns false, telling the handler to stop.
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func decodeJSON(w http.ResponseWriter, r *http.Request, dst any) bool {
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r.Body = http.MaxBytesReader(w, r.Body, maxBodySize)
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dec := json.NewDecoder(r.Body)
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dec.DisallowUnknownFields()
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if err := dec.Decode(dst); err != nil {
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writeError(w, http.StatusBadRequest, "invalid_json", "request body is not valid JSON: "+err.Error())
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return false
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}
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return true
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}
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