entc/gen: introduce the entc.Dependency option

examples/entcpkg/ent/config.go

@@ -7,6 +7,9 @@
 package ent
 
 import (
+	"io"
+	"net/http"
+
 	"entgo.io/ent"
 	"entgo.io/ent/dialect"
 )
@@ -23,7 +26,9 @@ type config struct {
 	// log used for logging on debug mode.
 	log func(...interface{})
 	// hooks to execute on mutations.
-	hooks *hooks
+	hooks      *hooks
+	HTTPClient *http.Client
+	Writer     io.Writer
 }
 
 // hooks per client, for fast access.
@@ -61,3 +66,17 @@ func Driver(driver dialect.Driver) Option {
 		c.driver = driver
 	}
 }
+
+// HTTPClient configures the HTTPClient.
+func HTTPClient(v *http.Client) Option {
+	return func(c *config) {
+		c.HTTPClient = v
+	}
+}
+
+// Writer configures the Writer.
+func Writer(v io.Writer) Option {
+	return func(c *config) {
+		c.Writer = v
+	}
+}

examples/entcpkg/ent/entc.go

@@ -10,12 +10,14 @@ package main
 import (
 	"fmt"
 	"log"
+	"net/http"
 	"strings"
 	"text/template"
 
 	"entgo.io/ent/entc"
 	"entgo.io/ent/entc/gen"
 	"entgo.io/ent/schema"
+	"entgo.io/ent/schema/field"
 )
 
 func main() {
@@ -23,9 +25,20 @@ func main() {
 	if err != nil {
 		log.Fatalf("creating extension: %v", err)
 	}
-	// A usage for custom options to configure the
+	// A usage for custom options to configure the code generator to use
+	// an extension and inject external dependencies in the generated API.
 	opts := []entc.Option{
 		entc.Extensions(ex),
+		entc.Dependency(
+			entc.DependencyType(&http.Client{}),
+		),
+		entc.Dependency(
+			entc.DependencyName("Writer"),
+			entc.DependencyTypeInfo(&field.TypeInfo{
+				Ident:   "io.Writer",
+				PkgPath: "io",
+			}),
+		),
 	}
 	err = entc.Generate("./schema", &gen.Config{
 		Header: `

examples/entcpkg/example_test.go

@@ -8,20 +8,36 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"net/http"
+	"os"
 
 	"entgo.io/ent/examples/entcpkg/ent"
+	"entgo.io/ent/examples/entcpkg/ent/hook"
 
 	_ "github.com/mattn/go-sqlite3"
 )
 
 func Example_EntcPkg() {
-	client, err := ent.Open("sqlite3", "file:ent?mode=memory&cache=shared&_fk=1")
+	client, err := ent.Open(
+		"sqlite3",
+		"file:ent?mode=memory&cache=shared&_fk=1",
+		ent.Writer(os.Stdout),
+		ent.HTTPClient(http.DefaultClient),
+	)
 	if err != nil {
 		log.Fatalf("failed opening connection to sqlite: %v", err)
 	}
 	defer client.Close()
+	// An example for using the injected dependencies in the generated builders.
+	client.User.Use(func(next ent.Mutator) ent.Mutator {
+		return hook.UserFunc(func(ctx context.Context, m *ent.UserMutation) (ent.Value, error) {
+			_ = m.HTTPClient
+			_ = m.Writer
+			return next.Mutate(ctx, m)
+		})
+	})
 	ctx := context.Background()
-	// run the auto migration tool.
+	// Run the auto migration tool.
 	if err := client.Schema.Create(ctx); err != nil {
 		log.Fatalf("failed creating schema resources: %v", err)
 	}