templates: make state changing routes to POST method (#5541)

- pkg/context: add ParamsUser to unify the injection process

pkg/context/user.go

@@ -0,0 +1,30 @@
+// Copyright 2018 The Gogs Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package context
+
+import (
+	"gopkg.in/macaron.v1"
+
+	"github.com/gogs/gogs/models"
+	"github.com/gogs/gogs/models/errors"
+)
+
+// ParamsUser is the wrapper type of the target user defined by URL parameter, namely ':username'.
+type ParamsUser struct {
+	*models.User
+}
+
+// InjectParamsUser returns a handler that retrieves target user based on URL parameter ':username',
+// and injects it as *ParamsUser.
+func InjectParamsUser() macaron.Handler {
+	return func(c *Context) {
+		user, err := models.GetUserByName(c.Params(":username"))
+		if err != nil {
+			c.NotFoundOrServerError("GetUserByName", errors.IsUserNotExist, err)
+			return
+		}
+		c.Map(&ParamsUser{user})
+	}
+}