87 lines
2.5 KiB
Go
87 lines
2.5 KiB
Go
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package httputil
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import (
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"context"
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"encoding/json"
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"net/http"
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"code.nochebuena.dev/go/valid"
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"code.nochebuena.dev/go/xerrors"
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)
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// HandlerFunc is an http.Handler that can return an error.
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// On non-nil error the error is mapped to the appropriate HTTP response via Error.
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// Useful for manual handlers that don't need the typed adapter.
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type HandlerFunc func(w http.ResponseWriter, r *http.Request) error
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func (h HandlerFunc) ServeHTTP(w http.ResponseWriter, r *http.Request) {
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if err := h(w, r); err != nil {
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Error(w, err)
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}
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}
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// Handle adapts a typed business function to http.HandlerFunc.
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// - Decodes JSON request body into Req.
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// - Validates Req using the provided Validator.
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// - Calls fn with the request context and decoded Req.
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// - Encodes Res as JSON with HTTP 200.
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// - Maps any returned error to the appropriate HTTP status via xerrors code.
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func Handle[Req, Res any](v valid.Validator, fn func(ctx context.Context, req Req) (Res, error)) http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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var req Req
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if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
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Error(w, badRequest("invalid JSON: "+err.Error()))
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return
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}
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if err := v.Struct(req); err != nil {
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Error(w, err)
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return
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}
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res, err := fn(r.Context(), req)
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if err != nil {
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Error(w, err)
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return
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}
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JSON(w, http.StatusOK, res)
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}
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}
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// HandleNoBody adapts a typed function with no request body (GET, DELETE).
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// Calls fn with request context; encodes result as JSON with HTTP 200.
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func HandleNoBody[Res any](fn func(ctx context.Context) (Res, error)) http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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res, err := fn(r.Context())
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if err != nil {
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Error(w, err)
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return
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}
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JSON(w, http.StatusOK, res)
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}
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}
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// HandleEmpty adapts a typed function with a body but no response body (returns 204).
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// Decodes JSON body into Req, validates, calls fn. Returns 204 on success.
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func HandleEmpty[Req any](v valid.Validator, fn func(ctx context.Context, req Req) error) http.HandlerFunc {
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return func(w http.ResponseWriter, r *http.Request) {
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var req Req
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if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
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Error(w, badRequest("invalid JSON: "+err.Error()))
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return
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}
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if err := v.Struct(req); err != nil {
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Error(w, err)
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return
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}
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if err := fn(r.Context(), req); err != nil {
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Error(w, err)
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return
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}
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NoContent(w)
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}
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}
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// badRequest wraps a message in an ErrInvalidInput error.
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func badRequest(msg string) error {
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return xerrors.New(xerrors.ErrInvalidInput, msg)
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}
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