server_types.go

package codegen

import (
	"path/filepath"

	"goa.design/goa/codegen"
	"goa.design/goa/expr"
)

// ServerTypeFiles returns the HTTP transport type files.
func ServerTypeFiles(genpkg string, root *expr.RootExpr) []*codegen.File {
	fw := make([]*codegen.File, len(root.API.HTTP.Services))
	seen := make(map[string]struct{})
	for i, r := range root.API.HTTP.Services {
		fw[i] = serverType(genpkg, r, seen)
	}
	return fw
}

// serverType return the file containing the type definitions used by the HTTP
// transport for the given service server. seen keeps track of the names of the
// types that have already been generated to prevent duplicate code generation.
//
// Below are the rules governing whether values are pointers or not. Note that
// the rules only applies to values that hold primitive types, values that hold
// slices, maps or objects always use pointers either implicitly - slices and
// maps - or explicitly - objects.
//
//   * The payload struct fields (if a struct) hold pointers when not required
//     and have no default value.
//
//   * Request body fields (if the body is a struct) always hold pointers to
//     allow for explicit validation.
//
//   * Request header, path and query string parameter variables hold pointers
//     when not required. Request header, body fields and param variables that
//     have default values are never required (enforced by DSL engine).
//
//   * The result struct fields (if a struct) hold pointers when not required
//     or have a default value (so generated code can set when null)
//
//   * Response body fields (if the body is a struct) and header variables hold
//     pointers when not required and have no default value.
//
func serverType(genpkg string, svc *expr.HTTPServiceExpr, seen map[string]struct{}) *codegen.File {
	var (
		path    string
		data    = HTTPServices.Get(svc.Name())
		svcName = codegen.SnakeCase(data.Service.VarName)
	)
	path = filepath.Join(codegen.Gendir, "http", svcName, "server", "types.go")
	header := codegen.Header(svc.Name()+" HTTP server types", "server",
		[]*codegen.ImportSpec{
			{Path: "unicode/utf8"},
			{Path: genpkg + "/" + svcName, Name: data.Service.PkgName},
			{Path: "goa.design/goa", Name: "goa"},
			{Path: genpkg + "/" + svcName + "/" + "views", Name: data.Service.ViewsPkg},
		},
	)

	var (
		initData       []*InitData
		validatedTypes []*TypeData

		sections = []*codegen.SectionTemplate{header}
	)

	// request body types
	for _, a := range svc.HTTPEndpoints {
		adata := data.Endpoint(a.Name())
		if data := adata.Payload.Request.ServerBody; data != nil {
			if data.Def != "" {
				sections = append(sections, &codegen.SectionTemplate{
					Name:   "request-body-type-decl",
					Source: typeDeclT,
					Data:   data,
				})
			}
			if data.ValidateDef != "" {
				validatedTypes = append(validatedTypes, data)
			}
		}
		if adata.ServerWebSocket != nil {
			if data := adata.ServerWebSocket.Payload; data != nil {
				if data.Def != "" {
					sections = append(sections, &codegen.SectionTemplate{
						Name:   "request-stream-payload-type-decl",
						Source: typeDeclT,
						Data:   data,
					})
				}
				if data.ValidateDef != "" {
					validatedTypes = append(validatedTypes, data)
				}
			}
		}
	}

	// response body types
	for _, a := range svc.HTTPEndpoints {
		adata := data.Endpoint(a.Name())
		for _, resp := range adata.Result.Responses {
			for _, tdata := range resp.ServerBody {
				if generated, ok := data.ServerTypeNames[tdata.Name]; ok && !generated {
					if tdata.Def != "" {
						sections = append(sections, &codegen.SectionTemplate{
							Name:   "response-server-body",
							Source: typeDeclT,
							Data:   tdata,
						})
					}
					if tdata.Init != nil {
						initData = append(initData, tdata.Init)
					}
					if tdata.ValidateDef != "" {
						validatedTypes = append(validatedTypes, tdata)
					}
					data.ServerTypeNames[tdata.Name] = true
				}
			}
		}
	}

	// error body types
	for _, a := range svc.HTTPEndpoints {
		adata := data.Endpoint(a.Name())
		for _, gerr := range adata.Errors {
			for _, herr := range gerr.Errors {
				for _, data := range herr.Response.ServerBody {
					if data.Def != "" {
						sections = append(sections, &codegen.SectionTemplate{
							Name:   "error-body-type-decl",
							Source: typeDeclT,
							Data:   data,
						})
					}
					if data.Init != nil {
						initData = append(initData, data.Init)
					}
					if data.ValidateDef != "" {
						validatedTypes = append(validatedTypes, data)
					}
				}
			}
		}
	}

	// body attribute types
	for _, tdata := range data.ServerBodyAttributeTypes {
		if tdata.Def != "" {
			sections = append(sections, &codegen.SectionTemplate{
				Name:   "server-body-attributes",
				Source: typeDeclT,
				Data:   tdata,
			})
		}

		if tdata.ValidateDef != "" {
			validatedTypes = append(validatedTypes, tdata)
		}
	}

	// body constructors
	for _, init := range initData {
		sections = append(sections, &codegen.SectionTemplate{
			Name:   "server-body-init",
			Source: serverBodyInitT,
			Data:   init,
		})
	}

	for _, adata := range data.Endpoints {
		// request to method payload
		if init := adata.Payload.Request.PayloadInit; init != nil {
			sections = append(sections, &codegen.SectionTemplate{
				Name:    "server-payload-init",
				Source:  serverTypeInitT,
				Data:    init,
				FuncMap: map[string]interface{}{"fieldCode": fieldCode},
			})
		}
		if isWebSocketEndpoint(adata) && adata.ServerWebSocket.Payload != nil {
			if init := adata.ServerWebSocket.Payload.Init; init != nil {
				sections = append(sections, &codegen.SectionTemplate{
					Name:    "server-payload-init",
					Source:  serverTypeInitT,
					Data:    init,
					FuncMap: map[string]interface{}{"fieldCode": fieldCode},
				})
			}
		}
	}

	// validate methods
	for _, data := range validatedTypes {
		sections = append(sections, &codegen.SectionTemplate{
			Name:   "server-validate",
			Source: validateT,
			Data:   data,
		})
	}

	return &codegen.File{Path: path, SectionTemplates: sections}
}

// fieldCode returns the code to initialize the return struct fields. It is
// used only in templates.
func fieldCode(init *InitData, typ string) string {
	varn := "res"
	if init.ReturnTypeAttribute == "" {
		varn = "v"
	}
	args := init.ServerArgs
	if typ == "client" {
		args = init.ClientArgs
	}
	mustInit := false
	if (typ == "server" && init.ServerCode == "") || (typ == "client" && init.ClientCode == "") {
		mustInit = true
	}
	initArgs := make([]*codegen.InitArgData, len(args))
	for i, arg := range args {
		initArgs[i] = &codegen.InitArgData{
			Name:         arg.VarName,
			Pointer:      arg.Pointer,
			Type:         arg.Type,
			FieldName:    arg.FieldName,
			FieldPointer: arg.FieldPointer,
			FieldType:    arg.FieldType,
		}
	}
	// We can ignore the transform helpers as there won't be any generated
	// because the headers and params cannot be user types.
	c, _, err := codegen.InitStructFields(initArgs, init.ReturnTypeName, varn, "", init.ReturnTypePkg, mustInit)
	if err != nil {
		panic(err) //bug
	}
	return c
}

// input: TypeData
const typeDeclT = `{{ comment .Description }}
type {{ .VarName }} {{ .Def }}
`

// input: InitData
const serverTypeInitT = `{{ comment .Description }}
func {{ .Name }}({{- range .ServerArgs }}{{ .VarName }} {{ .TypeRef }}, {{ end }}) {{ .ReturnTypeRef }} {
{{- if .ServerCode }}
	{{ .ServerCode }}
	{{- if .ReturnTypeAttribute }}
		res := &{{ .ReturnTypeName }}{
			{{ .ReturnTypeAttribute }}: {{ if .ReturnIsPrimitivePointer }}&{{ end }}v,
		}
	{{- end }}
{{- end }}
{{- if .ReturnIsStruct }}
	{{- if not .ServerCode }}
	{{ if .ReturnTypeAttribute }}res{{ else }}v{{ end }} := &{{ .ReturnTypeName }}{}
	{{- end }}
	{{ fieldCode . "server" }}
{{- end }}
	return {{ if .ReturnTypeAttribute }}res{{ else }}v{{ end }}
}
`

// input: InitData
const serverBodyInitT = `{{ comment .Description }}
func {{ .Name }}({{ range .ServerArgs }}{{ .VarName }} {{.TypeRef }}, {{ end }}) {{ .ReturnTypeRef }} {
	{{ .ServerCode }}
	return body
}
`

// input: TypeData
const validateT = `{{ printf "Validate%s runs the validations defined on %s" .VarName .Name | comment }}
func Validate{{ .VarName }}(body {{ .Ref }}) (err error) {
	{{ .ValidateDef }}
	return
}
`