add endpoint to update blog article

backend/blog.go

@@ -41,6 +41,8 @@ type ArticleFile struct {
 	Data []byte
 }
 
+const maxArticleFormSize = 10 * 1024 * 1024
+
 func ParseArticle(reader io.Reader, filePrefix string) (*Article, error) {
 	tarFiles := make(map[string][]byte)
 	tarReader := tar.NewReader(reader)
@@ -197,7 +199,7 @@ func (h *ApiHandler) ServeBlogGet(writer http.ResponseWriter, request *http.Requ
 }
 
 func (h *ApiHandler) ServeBlogPut(writer http.ResponseWriter, request *http.Request) {
-	err := request.ParseMultipartForm(10 * 1024 * 1024)
+	err := request.ParseMultipartForm(maxArticleFormSize)
 	if err != nil {
 		WriteError(writer, http.StatusBadRequest, "failed to parse multipart form", nil)
 		return
@@ -259,6 +261,47 @@ func (h *ApiHandler) ServeBlogGetSingle(writer http.ResponseWriter, request *htt
 	WriteResponse(writer, http.StatusOK, article)
 }
 
+func (h *ApiHandler) ServeBlogPatch(writer http.ResponseWriter, request *http.Request) {
+	idStr := request.PathValue("id")
+	id, err := strconv.ParseInt(idStr, 10, 64)
+	if err != nil {
+		WriteError(writer, http.StatusBadRequest, "invalid id", err)
+		return
+	}
+
+	err = request.ParseMultipartForm(maxArticleFormSize)
+	if err != nil {
+		WriteError(writer, http.StatusBadRequest, "failed to parse multipart form", nil)
+		return
+	}
+
+	file, _, err := request.FormFile("file")
+	if err != nil {
+		WriteError(writer, http.StatusBadRequest, "failed to parse file", nil)
+		return
+	}
+	defer func() {
+		_ = file.Close()
+	}()
+
+	article, err := ParseArticle(file, "/api/blog/"+strconv.FormatInt(id, 10)+"/file/")
+	if err != nil {
+		WriteError(writer, http.StatusInternalServerError, "failed to parse article: "+err.Error(), nil)
+		return
+	}
+
+	article.Id = id
+	err = h.db.UpdateBlogArticle(article)
+	if err != nil {
+		WriteError(writer, http.StatusInternalServerError, "failed to write database", err)
+		return
+	}
+
+	log.Printf("updated blog article '%s' with id %d", article.Title, article.Id)
+
+	WriteResponse(writer, http.StatusOK, map[string]interface{}{})
+}
+
 func (h *ApiHandler) ServeBlogDelete(writer http.ResponseWriter, request *http.Request) {
 	idStr := request.PathValue("id")
 	id, err := strconv.ParseInt(idStr, 10, 64)