Apollo Federation MVP

Author: marwan-at-work

api/generate.go

@@ -6,6 +6,7 @@ import (
 	"github.com/99designs/gqlgen/codegen"
 	"github.com/99designs/gqlgen/codegen/config"
 	"github.com/99designs/gqlgen/plugin"
+	"github.com/99designs/gqlgen/plugin/federation"
 	"github.com/99designs/gqlgen/plugin/modelgen"
 	"github.com/99designs/gqlgen/plugin/resolvergen"
 	"github.com/99designs/gqlgen/plugin/schemaconfig"
@@ -18,17 +19,33 @@ func Generate(cfg *config.Config, option ...Option) error {
 	if cfg.Model.IsDefined() {
 		_ = syscall.Unlink(cfg.Model.Filename)
 	}
+	if err := cfg.Check(); err != nil {
+		return errors.Wrap(err, "generating core failed")
+	}
 
 	plugins := []plugin.Plugin{schemaconfig.New()}
 	if cfg.Model.IsDefined() {
 		plugins = append(plugins, modelgen.New())
 	}
 	plugins = append(plugins, resolvergen.New())
+	if cfg.Federated {
+		plugins = append([]plugin.Plugin{federation.New()}, plugins...)
+	}
 
 	for _, o := range option {
 		o(cfg, &plugins)
 	}
 
+	schemaMutators := []codegen.SchemaMutator{}
+	for _, p := range plugins {
+		if inj, ok := p.(plugin.SourcesInjector); ok {
+			inj.InjectSources(cfg)
+		}
+		if mut, ok := p.(codegen.SchemaMutator); ok {
+			schemaMutators = append(schemaMutators, mut)
+		}
+	}
+
 	for _, p := range plugins {
 		if mut, ok := p.(plugin.ConfigMutator); ok {
 			err := mut.MutateConfig(cfg)
@@ -38,7 +55,7 @@ func Generate(cfg *config.Config, option ...Option) error {
 		}
 	}
 	// Merge again now that the generated models have been injected into the typemap
-	data, err := codegen.BuildData(cfg)
+	data, err := codegen.BuildData(cfg, schemaMutators)
 	if err != nil {
 		return errors.Wrap(err, "merging type systems failed")
 	}
@@ -56,6 +73,10 @@ func Generate(cfg *config.Config, option ...Option) error {
 		}
 	}
 
+	if err = codegen.GenerateCode(data); err != nil {
+		return errors.Wrap(err, "generating core failed")
+	}
+
 	if !cfg.SkipValidation {
 		if err := validate(cfg); err != nil {
 			return errors.Wrap(err, "validation failed")

codegen/config/config.go

@@ -30,6 +30,8 @@ type Config struct {
 	Directives               map[string]DirectiveConfig `yaml:"directives,omitempty"`
 	OmitSliceElementPointers bool                       `yaml:"omit_slice_element_pointers,omitempty"`
 	SkipValidation           bool                       `yaml:"skip_validation,omitempty"`
+	Federated                bool                       `yaml:"federated,omitempty"`
+	AdditionalSources        []*ast.Source              `yaml:"-"`
 }
 
 var cfgFilenames = []string{".gqlgen.yml", "gqlgen.yml", "gqlgen.yaml"}
@@ -148,8 +150,9 @@ type TypeMapEntry struct {
 }
 
 type TypeMapField struct {
-	Resolver  bool   `yaml:"resolver"`
-	FieldName string `yaml:"fieldName"`
+	Resolver        bool   `yaml:"resolver"`
+	FieldName       string `yaml:"fieldName"`
+	GeneratedMethod string `yaml:"-"`
 }
 
 type StringList []string
@@ -486,12 +489,9 @@ func (c *Config) InjectBuiltins(s *ast.Schema) {
 	}
 }
 
-func (c *Config) LoadSchema() (*ast.Schema, map[string]string, error) {
-	schemaStrings := map[string]string{}
-
-	sources := make([]*ast.Source, len(c.SchemaFilename))
-
-	for i, filename := range c.SchemaFilename {
+func (c *Config) LoadSchema() (*ast.Schema, error) {
+	sources := append([]*ast.Source{}, c.AdditionalSources...)
+	for _, filename := range c.SchemaFilename {
 		filename = filepath.ToSlash(filename)
 		var err error
 		var schemaRaw []byte
@@ -500,15 +500,14 @@ func (c *Config) LoadSchema() (*ast.Schema, map[string]string, error) {
 			fmt.Fprintln(os.Stderr, "unable to open schema: "+err.Error())
 			os.Exit(1)
 		}
-		schemaStrings[filename] = string(schemaRaw)
-		sources[i] = &ast.Source{Name: filename, Input: schemaStrings[filename]}
+		sources = append(sources, &ast.Source{Name: filename, Input: string(schemaRaw)})
 	}
 
 	schema, err := gqlparser.LoadSchema(sources...)
 	if err != nil {
-		return nil, nil, err
+		return nil, err
 	}
-	return schema, schemaStrings, nil
+	return schema, nil
 }
 
 func abs(path string) string {

codegen/data.go

@@ -1,12 +1,14 @@
 package codegen
 
 import (
+	"bytes"
 	"fmt"
 	"sort"
 
 	"github.com/99designs/gqlgen/codegen/config"
 	"github.com/pkg/errors"
 	"github.com/vektah/gqlparser/ast"
+	"github.com/vektah/gqlparser/formatter"
 )
 
 // Data is a unified model of the code to be generated. Plugins may modify this structure to do things like implement
@@ -35,13 +37,17 @@ type builder struct {
 	Directives map[string]*Directive
 }
 
-func BuildData(cfg *config.Config) (*Data, error) {
+type SchemaMutator interface {
+	MutateSchema(s *ast.Schema) error
+}
+
+func BuildData(cfg *config.Config, plugins []SchemaMutator) (*Data, error) {
 	b := builder{
 		Config: cfg,
 	}
 
 	var err error
-	b.Schema, b.SchemaStr, err = cfg.LoadSchema()
+	b.Schema, err = cfg.LoadSchema()
 	if err != nil {
 		return nil, err
 	}
@@ -58,6 +64,13 @@ func BuildData(cfg *config.Config) (*Data, error) {
 
 	cfg.InjectBuiltins(b.Schema)
 
+	for _, p := range plugins {
+		err = p.MutateSchema(b.Schema)
+		if err != nil {
+			return nil, fmt.Errorf("error running MutateSchema: %v", err)
+		}
+	}
+
 	b.Binder, err = b.Config.NewBinder(b.Schema)
 	if err != nil {
 		return nil, err
@@ -143,6 +156,10 @@ func BuildData(cfg *config.Config) (*Data, error) {
 		return nil, fmt.Errorf("invalid types were encountered while traversing the go source code, this probably means the invalid code generated isnt correct. add try adding -v to debug")
 	}
 
+	var buf bytes.Buffer
+	formatter.NewFormatter(&buf).FormatSchema(b.Schema)
+	s.SchemaStr = map[string]string{"schema.graphql": buf.String()}
+
 	return &s, nil
 }
 

codegen/directives.gotpl

@@ -1,6 +1,9 @@
 {{ define "implDirectives" }}{{ $in := .DirectiveObjName }}
 	{{- range $i, $directive := .ImplDirectives -}}
 		directive{{add $i 1}} := func(ctx context.Context) (interface{}, error) {
+			if ec.directives.{{ $directive.Name|ucFirst }} == nil {
+				return directive0(ctx)
+			}
 			{{- range $arg := $directive.Args }}
 				{{- if notNil "Value" $arg }}
 						{{ $arg.VarName }}, err := ec.{{ $arg.TypeReference.UnmarshalFunc }}(ctx, {{ $arg.Value | dump }})

codegen/field.go

@@ -98,6 +98,18 @@ func (b *builder) bindField(obj *Object, f *Field) (errret error) {
 		f.GoReceiverName = "ec"
 		f.GoFieldName = "introspectType"
 		return nil
+	case f.Name == "_entities":
+		f.GoFieldType = GoFieldMethod
+		f.GoReceiverName = "ec"
+		f.GoFieldName = "__resolve_entities"
+		f.MethodHasContext = true
+		return nil
+	case f.Name == "_service":
+		f.GoFieldType = GoFieldMethod
+		f.GoReceiverName = "ec"
+		f.GoFieldName = "__resolve__service"
+		f.MethodHasContext = true
+		return nil
 	case obj.Root:
 		f.IsResolver = true
 		return nil