Allow preserve_resolver config to work for layout follow schema

.github/workflows/check-coverage

@@ -7,4 +7,4 @@ go test -covermode atomic -coverprofile=/tmp/coverage.out.tmp -coverpkg=./... $(
 # ignore protobuf files
 cat /tmp/coverage.out.tmp | grep -v ".pb.go" > /tmp/coverage.out
 
-goveralls -coverprofile=/tmp/coverage.out -service=github -ignore='_examples/*/*,_examples/*/*/*,integration/*,integration/*/*,codegen/testserver/*/*,plugin/federation/testdata/*/*/*,*/generated.go,*/*/generated.go,*/*/*/generated.go,graphql/executable_schema_mock.go'
+goveralls -coverprofile=/tmp/coverage.out -service=github -ignore='_examples/*/*,_examples/*/*/*,integration/*,integration/*/*,codegen/testserver/*/*,plugin/resolvergen/testdata/*/*,plugin/modelgen/*/*,plugin/federation/testdata/*/*/*,*/generated.go,*/*/generated.go,*/*/*/generated.go,graphql/executable_schema_mock.go'

_examples/federation/subgraphs/subgraphs.go

@@ -7,11 +7,12 @@ import (
 	"log"
 	"net/http"
 
+	"golang.org/x/sync/errgroup"
+
 	"github.com/99designs/gqlgen/graphql"
 	"github.com/99designs/gqlgen/graphql/handler"
 	"github.com/99designs/gqlgen/graphql/handler/debug"
 	"github.com/99designs/gqlgen/graphql/playground"
-	"golang.org/x/sync/errgroup"
 )
 
 type Config struct {

client/readme.md

@@ -1,5 +1,8 @@
 This client is used internally for testing. I wanted a simple graphql client sent user specified queries.
 
 You might want to look at:
- - https://github.com/shurcooL/graphql: Uses reflection to build queries from structs. 
+ - https://github.com/shurcooL/graphql: Uses reflection to build queries from structs.
  - https://github.com/machinebox/graphql: Probably would have been a perfect fit, but it uses form encoding instead of json...
+ - [Khan/genqlient](https://github.com/Khan/genqlient) - Generate go GraphQL client from GraphQL query
+ - [infiotinc/gqlgenc](https://github.com/infiotinc/gqlgenc) - Generate go GraphQL client from GraphQL query
+ - [Yamashou/gqlgenc](https://github.com/Yamashou/gqlgenc) - Generate go GraphQL client from GraphQL query

codegen/config/resolver.go

@@ -56,9 +56,6 @@ func (r *ResolverConfig) Check() error {
 		} else {
 			r.Filename = abs(r.Filename)
 		}
-		if r.PreserveResolver {
-			return fmt.Errorf("preserve_resolver=true cannot be used with layout=%s", r.Layout)
-		}
 	default:
 		return fmt.Errorf("invalid layout %s. must be %s or %s", r.Layout, LayoutSingleFile, LayoutFollowSchema)
 	}

docs/content/config.md

@@ -46,6 +46,8 @@ resolver:
   # omit_template_comment: false
   # Optional: Pass in a path to a new gotpl template to use for generating resolvers
   # resolver_template: [your/path/resolver.gotpl]
+	# Optional: turn on to avoid rewriting existing resolver(s) when generating
+	# preserve_resolver: false
 
 # Optional: turn on use ` + "`" + `gqlgen:"fieldName"` + "`" + ` tags in your models
 # struct_tag: json

plugin/federation/constants.go

@@ -1,8 +1,9 @@
 package federation
 
 import (
-	"github.com/99designs/gqlgen/codegen/config"
 	"github.com/vektah/gqlparser/v2/ast"
+
+	"github.com/99designs/gqlgen/codegen/config"
 )
 
 // The name of the field argument that is injected into the resolver to support @requires.

plugin/resolvergen/resolver.go

@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"go/ast"
-	"io/fs"
 	"os"
 	"path/filepath"
 	"strings"
@@ -45,6 +44,7 @@ func (m *Plugin) GenerateCode(data *codegen.Data) error {
 	case config.LayoutSingleFile:
 		return m.generateSingleFile(data)
 	case config.LayoutFollowSchema:
+
 		return m.generatePerSchema(data)
 	}
 
@@ -54,10 +54,10 @@ func (m *Plugin) GenerateCode(data *codegen.Data) error {
 func (m *Plugin) generateSingleFile(data *codegen.Data) error {
 	file := File{}
 
-	if _, err := os.Stat(data.Config.Resolver.Filename); err == nil &&
+	if fileExists(data.Config.Resolver.Filename) &&
 		data.Config.Resolver.PreserveResolver {
 		// file already exists and config says not to update resolver
-		// with layout = single so just return
+		// so just return
 		return nil
 	}
 
@@ -93,7 +93,7 @@ func (m *Plugin) generateSingleFile(data *codegen.Data) error {
 		}
 	}
 
-	if _, err := os.Stat(data.Config.Resolver.Filename); err == nil {
+	if fileExists(data.Config.Resolver.Filename) {
 		file.name = data.Config.Resolver.Filename
 		file.imports = rewriter.ExistingImports(file.name)
 		file.RemainingSource = rewriter.RemainingSource(file.name)
@@ -196,6 +196,11 @@ func (m *Plugin) generatePerSchema(data *codegen.Data) error {
 	}
 
 	for _, file := range files {
+		if fileExists(file.name) &&
+			data.Config.Resolver.PreserveResolver {
+			// file already exists and config says not to update resolver
+			continue
+		}
 		resolverBuild := &ResolverBuild{
 			File:                file,
 			PackageName:         data.Config.Resolver.Package,
@@ -229,7 +234,7 @@ func (m *Plugin) generatePerSchema(data *codegen.Data) error {
 		}
 	}
 
-	if _, err := os.Stat(data.Config.Resolver.Filename); errors.Is(err, fs.ErrNotExist) {
+	if !fileExists(data.Config.Resolver.Filename) {
 		err := templates.Render(templates.Options{
 			PackageName: data.Config.Resolver.Package,
 			FileNotice: `
@@ -317,3 +322,10 @@ func readResolverTemplate(customResolverTemplate string) string {
 	}
 	return string(contentBytes)
 }
+
+func fileExists(fileName string) bool {
+	if _, err := os.Stat(fileName); err == nil {
+		return true
+	}
+	return false
+}

plugin/resolvergen/resolver_test.go

@@ -157,7 +157,7 @@ func overWriteFile(t *testing.T, sourceFile, destinationFile string) {
 	input, err := os.ReadFile(sourceFile)
 	require.NoError(t, err)
 
-	err = os.WriteFile(destinationFile, input, 0644)
+	err = os.WriteFile(destinationFile, input, 0o644)
 	require.NoError(t, err)
 }