Ability to return multiple errors from resolvers raise than add it to…

… stack. (#2454)

* Remove DO NOT EDIT

Sometimes vscode warn about this while editing resolvers code.
Finally the resolver's code is editable and generated at the same time.

* Ability to return multiple errors from resolver.

* Multiple errors return example

* Fix missing import

* reformat

* gofmt

* go generate ./...

* go generate ./...

* Regenerate

Signed-off-by: Steve Coffman <steve@khanacademy.org>

* remove trailing period

Signed-off-by: Steve Coffman <steve@khanacademy.org>

Signed-off-by: Steve Coffman <steve@khanacademy.org>
Co-authored-by: Roman A. Grigorovich <ragrigorov@mts.ru>
Co-authored-by: Steve Coffman <steve@khanacademy.org>

docs/content/reference/errors.md

@@ -19,11 +19,13 @@ package foo
 
 import (
 	"context"
+	"errors"
 
 	"github.com/vektah/gqlparser/v2/gqlerror"
 	"github.com/99designs/gqlgen/graphql"
 )
 
+// DoThings add errors to the stack.
 func (r Query) DoThings(ctx context.Context) (bool, error) {
 	// Print a formatted string
 	graphql.AddErrorf(ctx, "Error %d", 1)
@@ -60,6 +62,58 @@ They will be returned in the same order in the response, eg:
 }
 ```
 
+or you can simply return multiple errors
+
+```go
+package foo
+
+import (
+	"context"
+	"errors"
+
+	"github.com/vektah/gqlparser/v2/gqlerror"
+	"github.com/99designs/gqlgen/graphql"
+)
+
+var errSomethingWrong = errors.New("some validation failed")
+
+// DoThingsReturnMultipleErrors collect errors and returns it if any.
+func (r Query) DoThingsReturnMultipleErrors(ctx context.Context) (bool, error) {
+	errList := gqlerror.List{}
+
+	// Add existing error
+	errList = append(errList, gqlerror.Wrap(errSomethingWrong))
+
+	// Create new formatted and append
+	errList = append(errList, gqlerror.Errorf("invalid value: %s", "invalid"))
+
+	// Or fully customize the error and append
+	errList = append(errList, &gqlerror.Error{
+		Path:       graphql.GetPath(ctx),
+		Message:    "A descriptive error message",
+		Extensions: map[string]interface{}{
+			"code": "10-4",
+		},
+	})
+
+	return false, errList
+}
+```
+
+They will be returned in the same order in the response, eg:
+```json
+{
+  "data": {
+    "todo": null
+  },
+  "errors": [
+    { "message": "some validation failed", "path": [ "todo" ] },
+    { "message": "invalid value: invalid", "path": [ "todo" ] },
+    { "message": "A descriptive error message", "path": [ "todo" ], "extensions": { "code": "10-4" } },
+  ]
+}
+```
+
 ## Hooks
 
 ### The error presenter

graphql/context_operation.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 
 	"github.com/vektah/gqlparser/v2/ast"
+	"github.com/vektah/gqlparser/v2/gqlerror"
 )
 
 // Deprecated: Please update all references to OperationContext instead
@@ -109,6 +110,13 @@ func (c *OperationContext) Errorf(ctx context.Context, format string, args ...in
 // Error sends an error to the client, passing it through the formatter.
 // Deprecated: use graphql.AddError(ctx, err) instead
 func (c *OperationContext) Error(ctx context.Context, err error) {
+	if errList, ok := err.(gqlerror.List); ok {
+		for _, e := range errList {
+			AddError(ctx, e)
+		}
+		return
+	}
+
 	AddError(ctx, err)
 }
 

plugin/resolvergen/resolver.go

@@ -155,7 +155,7 @@ func (m *Plugin) generatePerSchema(data *codegen.Data) error {
 			FileNotice: `
 				// This file will be automatically regenerated based on the schema, any resolver implementations
 				// will be copied through when generating and any unknown code will be moved to the end.
-				// Code generated by github.com/99designs/gqlgen version ` + graphql.Version + ` DO NOT EDIT.`,
+				// Code generated by github.com/99designs/gqlgen version ` + graphql.Version,
 			Filename: filename,
 			Data:     resolverBuild,
 			Packages: data.Config.Packages,