entc/gen: add support for passing functions to external templates (#732)

Fixed #671

examples/entcpkg/ent/entc.go

@@ -8,10 +8,11 @@ package main
 
 import (
 	"log"
+	"strings"
+	"text/template"
 
 	"github.com/facebook/ent/entc"
 	"github.com/facebook/ent/entc/gen"
-	"github.com/facebook/ent/schema/field"
 )
 
 func main() {
@@ -23,7 +24,10 @@ func main() {
 
 			// Code generated by entc, DO NOT EDIT.
 		`,
-		IDType: &field.TypeInfo{Type: field.TypeInt},
+		// A usage for custom templates with external functions.
+		Template: template.Must(template.New("template").
+			Funcs(template.FuncMap{"title": strings.ToTitle}).
+			ParseFiles("template/static.tmpl")),
 	})
 	if err != nil {
 		log.Fatal("running ent codegen:", err)

examples/entcpkg/ent/template/static.tmpl

@@ -0,0 +1,9 @@
+{{/* A template for adding additional static fields to specific types. */}}
+{{ define "model/fields/additional" }}
+	{{- /* Add static fields to the "Card" entity. */}}
+	{{- if eq $.Name "User" }}
+		{{- /* A usage of an external function. */ -}}
+		// StaticField defined by templates (titled {{ title "staticField" }}).
+		StaticField string `json:"static_field,omitempty"`
+	{{- end }}
+{{ end }}

examples/entcpkg/ent/user.go

@@ -19,6 +19,9 @@ type User struct {
 	config
 	// ID of the ent.
 	ID int `json:"id,omitempty"`
+
+	// StaticField defined by templates (titled STATICFIELD).
+	StaticField string `json:"static_field,omitempty"`
 }
 
 // scanValues returns the types for scanning values from sql.Rows.