Move all mail related codes from models to services/mailer (#7200)

* move all mail related codes from models to modules/mailer

* fix lint

* use DBContext instead Engine

* use WithContext not WithEngine

* Use DBContext instead of Engine

* don't use defer when sess.Close()

* move DBContext to context.go and add some methods

* move mailer from modules/ to services

* fix lint

* fix tests

* fix fmt

* add gitea copyright

* fix tests

* don't expose db functions

* make code clear

* add DefaultDBContext

* fix build

* fix bug

1 files changed, 15 insertions, 0 deletions

diff --git a/models/error.go b/models/error.go
index c025437c50..9974287a0a 100644
--- a/models/error.go
+++ b/models/error.go
@@ -11,6 +11,21 @@ import (
 	"code.gitea.io/gitea/modules/git"
 )
 
+// ErrNotExist represents a non-exist error.
+type ErrNotExist struct {
+	ID int64
+}
+
+// IsErrNotExist checks if an error is an ErrNotExist
+func IsErrNotExist(err error) bool {
+	_, ok := err.(ErrNotExist)
+	return ok
+}
+
+func (err ErrNotExist) Error() string {
+	return fmt.Sprintf("record does not exist [id: %d]", err.ID)
+}
+
 // ErrNameReserved represents a "reserved name" error.
 type ErrNameReserved struct {
 	Name string