Add default struct validator pipeline (topfreegames#42)

app.go

@@ -39,6 +39,7 @@ import (
 	"github.com/topfreegames/pitaya/config"
 	"github.com/topfreegames/pitaya/constants"
 	pcontext "github.com/topfreegames/pitaya/context"
+	"github.com/topfreegames/pitaya/defaultpipelines"
 	"github.com/topfreegames/pitaya/errors"
 	"github.com/topfreegames/pitaya/internal/codec"
 	"github.com/topfreegames/pitaya/internal/message"
@@ -137,6 +138,7 @@ func Configure(
 	app.server.Metadata = serverMetadata
 	app.messageEncoder = message.NewMessagesEncoder(app.config.GetBool("pitaya.handler.messages.compression"))
 	configureMetrics(serverType)
+	configureDefaultPipelines(app.config)
 	app.configured = true
 }
 
@@ -161,7 +163,12 @@ func configureMetrics(serverType string) {
 			AddMetricsReporter(metricsReporter)
 		}
 	}
+}
 
+func configureDefaultPipelines(config *config.Config) {
+	if config.GetBool("pitaya.defaultpipelines.structvalidation.enabled") {
+		BeforeHandler(defaultpipelines.StructValidatorInstance.Validate)
+	}
 }
 
 // AddAcceptor adds a new acceptor to app

config/config.go

@@ -94,6 +94,7 @@ func (c *Config) fillDefaultValues() {
 		"pitaya.metrics.prometheus.port":                        9090,
 		"pitaya.metrics.prometheus.enabled":                     false,
 		"pitaya.metrics.tags":                                   map[string]string{},
+		"pitaya.defaultpipelines.structvalidation.enabled":      false,
 	}
 
 	for param := range defaultsMap {

defaultpipelines/default_struct_validator.go

@@ -0,0 +1,34 @@
+package defaultpipelines
+
+import (
+	"context"
+	"sync"
+
+	validator "gopkg.in/go-playground/validator.v9"
+)
+
+// DefaultValidator is the default arguments validator for handlers
+// in pitaya
+type DefaultValidator struct {
+	once     sync.Once
+	validate *validator.Validate
+}
+
+// Validate is the the function responsible for validating the 'in' parameter
+// based on the struct tags the parameter has.
+// This function has the pipeline.Handler signature so
+// it is possible to use it as a pipeline function
+func (v *DefaultValidator) Validate(ctx context.Context, in interface{}) (interface{}, error) {
+	v.lazyinit()
+	if err := v.validate.Struct(in); err != nil {
+		return nil, err
+	}
+
+	return in, nil
+}
+
+func (v *DefaultValidator) lazyinit() {
+	v.once.Do(func() {
+		v.validate = validator.New()
+	})
+}

defaultpipelines/struct_validator.go

@@ -0,0 +1,17 @@
+package defaultpipelines
+
+import (
+	"context"
+)
+
+// StructValidator is the interface that must be implemented
+// by a struct validator for the request arguments on pitaya.
+//
+// The default struct validator used by pitaya is https://github.com/go-playground/validator.
+type StructValidator interface {
+	Validate(context.Context, interface{}) (interface{}, error)
+}
+
+// StructValidatorInstance holds the default validator
+// on start but can be overridden if needed.
+var StructValidatorInstance StructValidator = &DefaultValidator{}

docs/configuration.rst

@@ -245,3 +245,21 @@ These configurations are only used if the modules are created. It is recommended
     - time.Time
     - Duration of the etcd lease before automatic renewal
 
+Default Pipelines
+=================
+
+These configurations control if the default pipelines should be enabled or not
+
+.. list-table::
+  :widths: 15 10 10 50
+  :header-rows: 1
+  :stub-columns: 1
+
+  * - Configuration
+    - Default value
+    - Type
+    - Description
+  * - pitaya.defaultpipelines.structvalidation.enabled
+    - false
+    - bool
+    - Whether Pitaya should enable the default struct validator for handler arguments

examples/demo/pipeline/main.go

@@ -6,11 +6,11 @@ import (
 	"fmt"
 
 	"github.com/sirupsen/logrus"
+	"github.com/spf13/viper"
 	"github.com/topfreegames/pitaya"
 	"github.com/topfreegames/pitaya/acceptor"
 	"github.com/topfreegames/pitaya/component"
 	"github.com/topfreegames/pitaya/serialize/json"
-	validator "gopkg.in/go-playground/validator.v9"
 )
 
 // MetagameServer ...
@@ -26,7 +26,10 @@ func NewMetagameMock() *MetagameServer {
 	}
 }
 
-// CreatePlayerCheatArgs ...
+// CreatePlayerCheatArgs is the struct used as parameter for the CreatePlayerCheat handler
+// Using the 'validate' tag it's possible to add validations on all struct fields.
+// For reference on the default validator see https://github.com/go-playground/validator.
+// Also, to enable this validation pipeline see docs/configuration.rst.
 type CreatePlayerCheatArgs struct {
 	Name         string `json:"name"`
 	Email        string `json:"email" validate:"email"`
@@ -47,20 +50,6 @@ func (g *MetagameServer) CreatePlayerCheat(ctx context.Context, args *CreatePlay
 	}, nil
 }
 
-// This is a beforeHandler that validates the handler argument based on the struct tags.
-// As for this example, the CreatePlayerCheatArgs has the 'validate' tags for email,
-// softCurrency and hardCurrency. If any of the validations fail an error will be returned
-func handlerParamsValidator(ctx context.Context, in interface{}) (interface{}, error) {
-	var validate *validator.Validate
-	validate = validator.New()
-
-	if err := validate.Struct(in); err != nil {
-		return nil, err
-	}
-
-	return in, nil
-}
-
 // Simple example of a before pipeline that actually asserts the type of the
 // in parameter.
 // IMPORTANT: that this kind of pipeline will be hard to exist in real code
@@ -99,13 +88,17 @@ func main() {
 	)
 
 	// Pipelines registration
-	pitaya.BeforeHandler(handlerParamsValidator)
 	pitaya.BeforeHandler(metagameServer.simpleBefore)
 	pitaya.AfterHandler(metagameServer.simpleAfter)
 
 	port := 3251
 	tcp := acceptor.NewTCPAcceptor(fmt.Sprintf(":%d", port))
 	pitaya.AddAcceptor(tcp)
-	pitaya.Configure(*isFrontend, *svType, pitaya.Cluster, map[string]string{})
+
+	config := viper.New()
+
+	// Enable default validator
+	config.Set("pitaya.defaultpipelines.structvalidation.enabled", true)
+	pitaya.Configure(*isFrontend, *svType, pitaya.Cluster, map[string]string{}, config)
 	pitaya.Start()
 }