[TT-8944] Refactor: move variable validation logic to separate step

pkg/graphql/execution_engine_v2.go

@@ -257,6 +257,17 @@ func (e *ExecutionEngineV2) ValidateForSchema(operation *Request) error {
 	return nil
 }
 
+func (e *ExecutionEngineV2) InputValidation(operation *Request) error {
+	result, err := operation.ValidateInput(e.config.schema)
+	if err != nil {
+		return err
+	}
+	if !result.Valid {
+		return result.Errors
+	}
+	return nil
+}
+
 func (e *ExecutionEngineV2) Setup(ctx context.Context, postProcessor *postprocess.Processor, resolveContext *resolve.Context, operation *Request, options ...ExecutionOptionsV2) {
 	for i := range options {
 		options[i](postProcessor, resolveContext)

pkg/graphql/execution_engine_v2_custom.go

@@ -23,6 +23,10 @@ type CustomExecutionEngineV2ValidatorStage interface {
 	ValidateForSchema(operation *Request) error
 }
 
+type CustomExecutionEngineV2InputValidationStage interface {
+	InputValidation(operation *Request) error
+}
+
 type CustomExecutionEngineV2ResolverStage interface {
 	Setup(ctx context.Context, postProcessor *postprocess.Processor, resolveContext *resolve.Context, operation *Request, options ...ExecutionOptionsV2)
 	Plan(postProcessor *postprocess.Processor, operation *Request, report *operationreport.Report) (plan.Plan, error)
@@ -34,6 +38,7 @@ type CustomExecutionEngineV2 interface {
 	CustomExecutionEngineV2NormalizerStage
 	CustomExecutionEngineV2ValidatorStage
 	CustomExecutionEngineV2ResolverStage
+	CustomExecutionEngineV2InputValidationStage
 }
 
 type ExecutionEngineV2Executor interface {
@@ -54,8 +59,9 @@ type CustomExecutionEngineV2RequiredStages struct {
 }
 
 type CustomExecutionEngineV2OptionalStages struct {
-	NormalizerStage CustomExecutionEngineV2NormalizerStage
-	ValidatorStage  CustomExecutionEngineV2ValidatorStage
+	NormalizerStage      CustomExecutionEngineV2NormalizerStage
+	ValidatorStage       CustomExecutionEngineV2ValidatorStage
+	InputValidationStage CustomExecutionEngineV2InputValidationStage
 }
 
 type CustomExecutionEngineV2Executor struct {
@@ -69,8 +75,9 @@ func NewCustomExecutionEngineV2Executor(executionEngineV2 CustomExecutionEngineV
 			ResolverStage: executionEngineV2,
 		},
 		OptionalStages: &CustomExecutionEngineV2OptionalStages{
-			NormalizerStage: executionEngineV2,
-			ValidatorStage:  executionEngineV2,
+			NormalizerStage:      executionEngineV2,
+			ValidatorStage:       executionEngineV2,
+			InputValidationStage: executionEngineV2,
 		},
 	}
 
@@ -117,6 +124,12 @@ func (c *CustomExecutionEngineV2Executor) Execute(ctx context.Context, operation
 		}
 	}
 
+	if c.ExecutionStages.OptionalStages != nil && c.ExecutionStages.OptionalStages.InputValidationStage != nil {
+		if err := c.ExecutionStages.OptionalStages.InputValidationStage.InputValidation(operation); err != nil {
+			return err
+		}
+	}
+
 	execContext := c.getExecutionCtx()
 	defer c.putExecutionCtx(execContext)
 	execContext.prepare(ctx, operation.Variables, operation.request)

pkg/graphql/input_validation.go

@@ -0,0 +1,44 @@
+package graphql
+
+import (
+	"github.com/TykTechnologies/graphql-go-tools/pkg/operationreport"
+	"github.com/TykTechnologies/graphql-go-tools/pkg/variablevalidator"
+)
+
+type InputValidationResult struct {
+	Valid  bool
+	Errors Errors
+}
+
+func inputValidationResultFromReport(report operationreport.Report) (InputValidationResult, error) {
+	result := InputValidationResult{
+		Valid:  false,
+		Errors: nil,
+	}
+
+	if !report.HasErrors() {
+		result.Valid = true
+		return result, nil
+	}
+
+	result.Errors = RequestErrorsFromOperationReport(report)
+
+	var err error
+	if len(report.InternalErrors) > 0 {
+		err = report.InternalErrors[0]
+	}
+
+	return result, err
+}
+
+func (r *Request) ValidateInput(schema *Schema) (InputValidationResult, error) {
+	validator := variablevalidator.NewVariableValidator()
+
+	report := r.parseQueryOnce()
+	if report.HasErrors() {
+		return inputValidationResultFromReport(report)
+	}
+	validator.Validate(&r.document, &schema.document, []byte(r.OperationName), r.Variables, &report)
+
+	return inputValidationResultFromReport(report)
+}

pkg/graphql/input_validation_test.go

@@ -0,0 +1,30 @@
+package graphql
+
+import (
+	"github.com/TykTechnologies/graphql-go-tools/pkg/starwars"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestRequest_ValidateInput(t *testing.T) {
+	t.Run("Should pass input validation", func(t *testing.T) {
+		schema := starwarsSchema(t)
+		request := requestForQuery(t, starwars.FileDroidWithArgAndVarQuery)
+		request.Variables = []byte(`{"droidID":"testID"}`)
+
+		result, err := request.ValidateInput(schema)
+		assert.NoError(t, err)
+		assert.True(t, result.Valid)
+		assert.Nil(t, result.Errors)
+	})
+
+	t.Run("Should fail input validation", func(t *testing.T) {
+		schema := starwarsSchema(t)
+		request := requestForQuery(t, starwars.FileDroidWithArgAndVarQuery)
+
+		result, err := request.ValidateInput(schema)
+		assert.NoError(t, err)
+		assert.False(t, result.Valid)
+		assert.Equal(t, `Required variable "$droidID" was not provided, locations: [{Line:1 Column:13}], path: [query]`, result.Errors.Error())
+	})
+}

pkg/operationreport/externalerror.go

@@ -27,6 +27,8 @@ const (
 	UnknownFieldOfInputObjectErrMsg         = `Field "%s" is not defined by type "%s".`
 	DuplicatedFieldInputObjectErrMsg        = `There can be only one input field named "%s".`
 	ValueIsNotAnInputObjectTypeErrMsg       = `Expected value of type "%s", found %s.`
+	VariableNotProvidedErrMsg               = `Required variable "$%s" was not provided`
+	VariableValidationFailedErrMsg          = `Validation for variable "%s" failed: %s`
 )
 
 type ExternalError struct {
@@ -242,6 +244,19 @@ func ErrValueIsNotAnInputObjectType(value, inputType ast.ByteSlice, position pos
 	return err
 }
 
+func ErrVariableNotProvided(name ast.ByteSlice, position position.Position) (err ExternalError) {
+	err.Message = fmt.Sprintf(VariableNotProvidedErrMsg, name)
+	err.Locations = LocationsFromPosition(position)
+
+	return err
+}
+
+func ErrVariableValidationFailed(name ast.ByteSlice, message string, position position.Position) (err ExternalError) {
+	err.Message = fmt.Sprintf(VariableValidationFailedErrMsg, name, message)
+	err.Locations = LocationsFromPosition(position)
+	return err
+}
+
 func ErrValueDoesntSatisfyString(value, inputType ast.ByteSlice, position position.Position) (err ExternalError) {
 	err.Message = fmt.Sprintf(NotStringErrMsg, inputType, value)
 	err.Locations = LocationsFromPosition(position)

pkg/variablevalidator/variablevalidator.go

@@ -0,0 +1,107 @@
+package variablevalidator
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"github.com/TykTechnologies/graphql-go-tools/pkg/ast"
+	"github.com/TykTechnologies/graphql-go-tools/pkg/astvisitor"
+	"github.com/TykTechnologies/graphql-go-tools/pkg/graphqljsonschema"
+	"github.com/TykTechnologies/graphql-go-tools/pkg/operationreport"
+	"github.com/buger/jsonparser"
+)
+
+type VariableValidator struct {
+	walker  *astvisitor.Walker
+	visitor *validatorVisitor
+}
+
+func NewVariableValidator() *VariableValidator {
+	walker := astvisitor.Walker{}
+	validator := VariableValidator{
+		walker: &walker,
+		visitor: &validatorVisitor{
+			Walker:           &walker,
+			currentOperation: ast.InvalidRef,
+		},
+	}
+
+	validator.walker.RegisterEnterDocumentVisitor(validator.visitor)
+	validator.walker.RegisterEnterOperationVisitor(validator.visitor)
+	validator.walker.RegisterLeaveOperationVisitor(validator.visitor)
+	validator.walker.RegisterEnterVariableDefinitionVisitor(validator.visitor)
+
+	return &validator
+}
+
+type validatorVisitor struct {
+	*astvisitor.Walker
+
+	operationName, variables []byte
+	currentOperation         int
+	operation, definition    *ast.Document
+}
+
+func (v *validatorVisitor) EnterDocument(operation, definition *ast.Document) {
+	v.operation, v.definition = operation, definition
+}
+
+func (v *validatorVisitor) EnterVariableDefinition(ref int) {
+	if v.currentOperation == ast.InvalidRef {
+		return
+	}
+	typeRef := v.operation.VariableDefinitions[ref].Type
+
+	variableName := v.operation.VariableDefinitionNameBytes(ref)
+	variable, t, _, err := jsonparser.Get(v.variables, string(variableName))
+	if t == jsonparser.NotExist && v.operation.TypeIsNonNull(typeRef) {
+		v.StopWithExternalErr(operationreport.ErrVariableNotProvided(variableName, v.operation.VariableDefinitions[ref].VariableValue.Position))
+		return
+	}
+	if err != nil {
+		v.StopWithInternalErr(errors.New("error parsing variables"))
+		return
+	}
+
+	if t == jsonparser.String {
+		variable = []byte(fmt.Sprintf(`"%s"`, string(variable)))
+	}
+
+	jsonSchema := graphqljsonschema.FromTypeRef(v.operation, v.definition, typeRef)
+	schemaValidator, err := graphqljsonschema.NewValidatorFromSchema(jsonSchema)
+	if err != nil {
+		v.StopWithInternalErr(err)
+		return
+	}
+	if err := schemaValidator.Validate(context.Background(), variable); err != nil {
+		v.StopWithExternalErr(operationreport.ErrVariableValidationFailed(variableName, err.Error(), v.operation.VariableDefinitions[ref].VariableValue.Position))
+		return
+	}
+}
+
+func (v *validatorVisitor) EnterOperationDefinition(ref int) {
+	if len(v.operationName) == 0 {
+		v.currentOperation = ref
+		return
+	}
+
+	if bytes.Equal(v.operationName, v.operation.OperationDefinitionNameBytes(ref)) {
+		v.currentOperation = ref
+	}
+}
+
+func (v *validatorVisitor) LeaveOperationDefinition(ref int) {
+	if v.currentOperation == ref {
+		v.Stop()
+	}
+}
+
+func (v *VariableValidator) Validate(operation, definition *ast.Document, operationName, variables []byte, report *operationreport.Report) {
+	if v.visitor != nil {
+		v.visitor.operationName = operationName
+		v.visitor.variables = variables
+	}
+
+	v.walker.Walk(operation, definition, report)
+}