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models.go
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models.go
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package modelgen
import (
_ "embed"
"fmt"
"go/types"
"sort"
"strings"
"text/template"
"github.com/99designs/gqlgen/codegen/config"
"github.com/99designs/gqlgen/codegen/templates"
"github.com/99designs/gqlgen/plugin"
"github.com/vektah/gqlparser/v2/ast"
)
//go:embed models.gotpl
var modelTemplate string
type (
BuildMutateHook = func(b *ModelBuild) *ModelBuild
FieldMutateHook = func(td *ast.Definition, fd *ast.FieldDefinition, f *Field) (*Field, error)
)
// DefaultFieldMutateHook is the default hook for the Plugin which applies the GoFieldHook and GoTagFieldHook.
func DefaultFieldMutateHook(td *ast.Definition, fd *ast.FieldDefinition, f *Field) (*Field, error) {
var err error
f, err = GoFieldHook(td, fd, f)
if err != nil {
return f, err
}
return GoTagFieldHook(td, fd, f)
}
// DefaultBuildMutateHook is the default hook for the Plugin which mutate ModelBuild.
func DefaultBuildMutateHook(b *ModelBuild) *ModelBuild {
return b
}
type ModelBuild struct {
PackageName string
Interfaces []*Interface
Models []*Object
Enums []*Enum
Scalars []string
}
type Interface struct {
Description string
Name string
Fields []*Field
Implements []string
}
type Object struct {
Description string
Name string
Fields []*Field
Implements []string
}
type Field struct {
Description string
// Name is the field's name as it appears in the schema
Name string
// GoName is the field's name as it appears in the generated Go code
GoName string
Type types.Type
Tag string
}
type Enum struct {
Description string
Name string
Values []*EnumValue
}
type EnumValue struct {
Description string
Name string
}
func New() plugin.Plugin {
return &Plugin{
MutateHook: DefaultBuildMutateHook,
FieldHook: DefaultFieldMutateHook,
}
}
type Plugin struct {
MutateHook BuildMutateHook
FieldHook FieldMutateHook
}
var _ plugin.ConfigMutator = &Plugin{}
func (m *Plugin) Name() string {
return "modelgen"
}
func (m *Plugin) MutateConfig(cfg *config.Config) error {
b := &ModelBuild{
PackageName: cfg.Model.Package,
}
for _, schemaType := range cfg.Schema.Types {
if cfg.Models.UserDefined(schemaType.Name) {
continue
}
switch schemaType.Kind {
case ast.Interface, ast.Union:
var fields []*Field
var err error
if !cfg.OmitGetters {
fields, err = m.generateFields(cfg, schemaType)
if err != nil {
return err
}
}
it := &Interface{
Description: schemaType.Description,
Name: schemaType.Name,
Implements: schemaType.Interfaces,
Fields: fields,
}
b.Interfaces = append(b.Interfaces, it)
case ast.Object, ast.InputObject:
if schemaType == cfg.Schema.Query || schemaType == cfg.Schema.Mutation || schemaType == cfg.Schema.Subscription {
continue
}
fields, err := m.generateFields(cfg, schemaType)
if err != nil {
return err
}
it := &Object{
Description: schemaType.Description,
Name: schemaType.Name,
Fields: fields,
}
// If Interface A implements interface B, and Interface C also implements interface B
// then both A and C have methods of B.
// The reason for checking unique is to prevent the same method B from being generated twice.
uniqueMap := map[string]bool{}
for _, implementor := range cfg.Schema.GetImplements(schemaType) {
if !uniqueMap[implementor.Name] {
it.Implements = append(it.Implements, implementor.Name)
uniqueMap[implementor.Name] = true
}
// for interface implements
for _, iface := range implementor.Interfaces {
if !uniqueMap[iface] {
it.Implements = append(it.Implements, iface)
uniqueMap[iface] = true
}
}
}
b.Models = append(b.Models, it)
case ast.Enum:
it := &Enum{
Name: schemaType.Name,
Description: schemaType.Description,
}
for _, v := range schemaType.EnumValues {
it.Values = append(it.Values, &EnumValue{
Name: v.Name,
Description: v.Description,
})
}
b.Enums = append(b.Enums, it)
case ast.Scalar:
b.Scalars = append(b.Scalars, schemaType.Name)
}
}
sort.Slice(b.Enums, func(i, j int) bool { return b.Enums[i].Name < b.Enums[j].Name })
sort.Slice(b.Models, func(i, j int) bool { return b.Models[i].Name < b.Models[j].Name })
sort.Slice(b.Interfaces, func(i, j int) bool { return b.Interfaces[i].Name < b.Interfaces[j].Name })
// if we are not just turning all struct-type fields in generated structs into pointers, we need to at least
// check for cyclical relationships and recursive structs
if !cfg.StructFieldsAlwaysPointers {
findAndHandleCyclicalRelationships(b)
}
for _, it := range b.Enums {
cfg.Models.Add(it.Name, cfg.Model.ImportPath()+"."+templates.ToGo(it.Name))
}
for _, it := range b.Models {
cfg.Models.Add(it.Name, cfg.Model.ImportPath()+"."+templates.ToGo(it.Name))
}
for _, it := range b.Interfaces {
cfg.Models.Add(it.Name, cfg.Model.ImportPath()+"."+templates.ToGo(it.Name))
}
for _, it := range b.Scalars {
cfg.Models.Add(it, "github.com/99designs/gqlgen/graphql.String")
}
if len(b.Models) == 0 && len(b.Enums) == 0 && len(b.Interfaces) == 0 && len(b.Scalars) == 0 {
return nil
}
if m.MutateHook != nil {
b = m.MutateHook(b)
}
getInterfaceByName := func(name string) *Interface {
// Allow looking up interfaces, so template can generate getters for each field
for _, i := range b.Interfaces {
if i.Name == name {
return i
}
}
return nil
}
gettersGenerated := make(map[string]map[string]struct{})
generateGetter := func(model *Object, field *Field) string {
if model == nil || field == nil {
return ""
}
// Let templates check if a given getter has been generated already
typeGetters, exists := gettersGenerated[model.Name]
if !exists {
typeGetters = make(map[string]struct{})
gettersGenerated[model.Name] = typeGetters
}
_, exists = typeGetters[field.GoName]
typeGetters[field.GoName] = struct{}{}
if exists {
return ""
}
_, interfaceFieldTypeIsPointer := field.Type.(*types.Pointer)
var structFieldTypeIsPointer bool
for _, f := range model.Fields {
if f.GoName == field.GoName {
_, structFieldTypeIsPointer = f.Type.(*types.Pointer)
break
}
}
goType := templates.CurrentImports.LookupType(field.Type)
if strings.HasPrefix(goType, "[]") {
getter := fmt.Sprintf("func (this %s) Get%s() %s {\n", templates.ToGo(model.Name), field.GoName, goType)
getter += fmt.Sprintf("\tif this.%s == nil { return nil }\n", field.GoName)
getter += fmt.Sprintf("\tinterfaceSlice := make(%s, 0, len(this.%s))\n", goType, field.GoName)
getter += fmt.Sprintf("\tfor _, concrete := range this.%s { interfaceSlice = append(interfaceSlice, ", field.GoName)
if interfaceFieldTypeIsPointer && !structFieldTypeIsPointer {
getter += "&"
} else if !interfaceFieldTypeIsPointer && structFieldTypeIsPointer {
getter += "*"
}
getter += "concrete) }\n"
getter += "\treturn interfaceSlice\n"
getter += "}"
return getter
} else {
getter := fmt.Sprintf("func (this %s) Get%s() %s { return ", templates.ToGo(model.Name), field.GoName, goType)
if interfaceFieldTypeIsPointer && !structFieldTypeIsPointer {
getter += "&"
} else if !interfaceFieldTypeIsPointer && structFieldTypeIsPointer {
getter += "*"
}
getter += fmt.Sprintf("this.%s }", field.GoName)
return getter
}
}
funcMap := template.FuncMap{
"getInterfaceByName": getInterfaceByName,
"generateGetter": generateGetter,
}
err := templates.Render(templates.Options{
PackageName: cfg.Model.Package,
Filename: cfg.Model.Filename,
Data: b,
GeneratedHeader: true,
Packages: cfg.Packages,
Template: modelTemplate,
Funcs: funcMap,
})
if err != nil {
return err
}
// We may have generated code in a package we already loaded, so we reload all packages
// to allow packages to be compared correctly
cfg.ReloadAllPackages()
return nil
}
func (m *Plugin) generateFields(cfg *config.Config, schemaType *ast.Definition) ([]*Field, error) {
binder := cfg.NewBinder()
fields := make([]*Field, 0)
for _, field := range schemaType.Fields {
var typ types.Type
fieldDef := cfg.Schema.Types[field.Type.Name()]
if cfg.Models.UserDefined(field.Type.Name()) {
var err error
typ, err = binder.FindTypeFromName(cfg.Models[field.Type.Name()].Model[0])
if err != nil {
return nil, err
}
} else {
switch fieldDef.Kind {
case ast.Scalar:
// no user defined model, referencing a default scalar
typ = types.NewNamed(
types.NewTypeName(0, cfg.Model.Pkg(), "string", nil),
nil,
nil,
)
case ast.Interface, ast.Union:
// no user defined model, referencing a generated interface type
typ = types.NewNamed(
types.NewTypeName(0, cfg.Model.Pkg(), templates.ToGo(field.Type.Name()), nil),
types.NewInterfaceType([]*types.Func{}, []types.Type{}),
nil,
)
case ast.Enum:
// no user defined model, must reference a generated enum
typ = types.NewNamed(
types.NewTypeName(0, cfg.Model.Pkg(), templates.ToGo(field.Type.Name()), nil),
nil,
nil,
)
case ast.Object, ast.InputObject:
// no user defined model, must reference a generated struct
typ = types.NewNamed(
types.NewTypeName(0, cfg.Model.Pkg(), templates.ToGo(field.Type.Name()), nil),
types.NewStruct(nil, nil),
nil,
)
default:
panic(fmt.Errorf("unknown ast type %s", fieldDef.Kind))
}
}
name := templates.ToGo(field.Name)
if nameOveride := cfg.Models[schemaType.Name].Fields[field.Name].FieldName; nameOveride != "" {
name = nameOveride
}
typ = binder.CopyModifiersFromAst(field.Type, typ)
if cfg.StructFieldsAlwaysPointers {
if isStruct(typ) && (fieldDef.Kind == ast.Object || fieldDef.Kind == ast.InputObject) {
typ = types.NewPointer(typ)
}
}
f := &Field{
Name: field.Name,
GoName: name,
Type: typ,
Description: field.Description,
Tag: `json:"` + field.Name + `"`,
}
if m.FieldHook != nil {
mf, err := m.FieldHook(schemaType, field, f)
if err != nil {
return nil, fmt.Errorf("generror: field %v.%v: %w", schemaType.Name, field.Name, err)
}
f = mf
}
fields = append(fields, f)
}
return fields, nil
}
// GoTagFieldHook applies the goTag directive to the generated Field f. When applying the Tag to the field, the field
// name is used when no value argument is present.
func GoTagFieldHook(td *ast.Definition, fd *ast.FieldDefinition, f *Field) (*Field, error) {
args := make([]string, 0)
for _, goTag := range fd.Directives.ForNames("goTag") {
key := ""
value := fd.Name
if arg := goTag.Arguments.ForName("key"); arg != nil {
if k, err := arg.Value.Value(nil); err == nil {
key = k.(string)
}
}
if arg := goTag.Arguments.ForName("value"); arg != nil {
if v, err := arg.Value.Value(nil); err == nil {
value = v.(string)
}
}
args = append(args, key+":\""+value+"\"")
}
if len(args) > 0 {
f.Tag = f.Tag + " " + strings.Join(args, " ")
}
return f, nil
}
// GoFieldHook applies the goField directive to the generated Field f.
func GoFieldHook(td *ast.Definition, fd *ast.FieldDefinition, f *Field) (*Field, error) {
args := make([]string, 0)
_ = args
for _, goField := range fd.Directives.ForNames("goField") {
if arg := goField.Arguments.ForName("name"); arg != nil {
if k, err := arg.Value.Value(nil); err == nil {
f.GoName = k.(string)
}
}
}
return f, nil
}
func isStruct(t types.Type) bool {
_, is := t.Underlying().(*types.Struct)
return is
}
// findAndHandleCyclicalRelationships checks for cyclical relationships between generated structs and replaces them
// with pointers. These relationships will produce compilation errors if they are not pointers.
// Also handles recursive structs.
func findAndHandleCyclicalRelationships(b *ModelBuild) {
for ii, structA := range b.Models {
for _, fieldA := range structA.Fields {
if strings.Contains(fieldA.Type.String(), "NotCyclicalA") {
fmt.Print()
}
if !isStruct(fieldA.Type) {
continue
}
// the field Type string will be in the form "github.com/99designs/gqlgen/codegen/testserver/followschema.LoopA"
// we only want the part after the last dot: "LoopA"
// this could lead to false positives, as we are only checking the name of the struct type, but these
// should be extremely rare, if it is even possible at all.
fieldAStructNameParts := strings.Split(fieldA.Type.String(), ".")
fieldAStructName := fieldAStructNameParts[len(fieldAStructNameParts)-1]
// find this struct type amongst the generated structs
for jj, structB := range b.Models {
if structB.Name != fieldAStructName {
continue
}
// check if structB contains a cyclical reference back to structA
var cyclicalReferenceFound bool
for _, fieldB := range structB.Fields {
if !isStruct(fieldB.Type) {
continue
}
fieldBStructNameParts := strings.Split(fieldB.Type.String(), ".")
fieldBStructName := fieldBStructNameParts[len(fieldBStructNameParts)-1]
if fieldBStructName == structA.Name {
cyclicalReferenceFound = true
fieldB.Type = types.NewPointer(fieldB.Type)
// keep looping in case this struct has additional fields of this type
}
}
// if this is a recursive struct (i.e. structA == structB), ensure that we only change this field to a pointer once
if cyclicalReferenceFound && ii != jj {
fieldA.Type = types.NewPointer(fieldA.Type)
break
}
}
}
}
}