contrib/gorm.io/gorm.v1: add context example

contrib/gorm.io/gorm.v1/example_test.go

@@ -6,16 +6,24 @@
 package gorm_test
 
 import (
+	"context"
 	"log"
 
 	sqltrace "gopkg.in/DataDog/dd-trace-go.v1/contrib/database/sql"
 	gormtrace "gopkg.in/DataDog/dd-trace-go.v1/contrib/gorm.io/gorm.v1"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/ext"
+	"gopkg.in/DataDog/dd-trace-go.v1/ddtrace/tracer"
 
 	"github.com/jackc/pgx/v4/stdlib"
 	"gorm.io/driver/postgres"
 	"gorm.io/gorm"
 )
 
+type User struct {
+	gorm.Model
+	Name string
+}
+
 func ExampleOpen() {
 	// Register augments the provided driver with tracing, enabling it to be loaded by gormtrace.Open.
 	sqltrace.Register("pgx", &stdlib.Driver{}, sqltrace.WithServiceName("my-service"))
@@ -29,11 +37,35 @@ func ExampleOpen() {
 		log.Fatal(err)
 	}
 
-	user := struct {
-		gorm.Model
-		Name string
-	}{}
+	user := User{}
 
 	// All calls through gorm.DB are now traced.
 	db.Where("name = ?", "jinzhu").First(&user)
 }
+
+func Example_context() {
+	// Register augments the provided driver with tracing, enabling it to be loaded by gormtrace.Open.
+	sqltrace.Register("pgx", &stdlib.Driver{}, sqltrace.WithServiceName("my-service"))
+	sqlDb, err := sqltrace.Open("pgx", "postgres://pqgotest:password@localhost/pqgotest?sslmode=disable")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	db, err := gormtrace.Open(postgres.New(postgres.Config{Conn: sqlDb}), &gorm.Config{})
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	user := User{}
+
+	// Create a root span, giving name, server and resource.
+	span, ctx := tracer.StartSpanFromContext(context.Background(), "my-query",
+		tracer.SpanType(ext.SpanTypeSQL),
+		tracer.ServiceName("my-db"),
+		tracer.ResourceName("initial-access"),
+	)
+	defer span.Finish()
+
+	// Subsequent spans inherit their parent from context.
+	db.WithContext(ctx).Where("name = ?", "jinzhu").First(&user)
+}