Add gqlgen custom code generator

backend/Makefile

@@ -27,7 +27,7 @@ gen: ## Generate GraphQL implementations
 	printf "${GREEN} Update gqlgen\n\n"; \
  	go get github.com/99designs/gqlgen@latest; cd ${ORG_PATH} ; \
 	printf "${GREEN} Generating GraphQL related sources\n\n"; \
-	go run github.com/99designs/gqlgen generate; cd ${ORG_PATH}; \
+	go run ./cmd/gqlgenerate; cd ${ORG_PATH}; \
 	printf "${GREEN}Done\n"; \
 
 .PHONY: fmt

backend/README.md

@@ -45,6 +45,11 @@ This backend uses some generated code. Here are the steps to generate code.
 2. At `/backend`, run `make parsergen`
 
 # Tips
+## How to generate GraphQL Model under /graph/model
+Right under the 
+```
+ go run ./cmd/gqlgenerate
+```
 ## How to see the Make Commands
 ```
 make help

backend/cmd/gqlgenerate/main.go

@@ -1 +1,75 @@
-package gqlgenerate
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+
+	"github.com/99designs/gqlgen/api"
+	"github.com/99designs/gqlgen/codegen/config"
+	"github.com/99designs/gqlgen/plugin/modelgen"
+	"github.com/vektah/gqlparser/v2/ast"
+)
+
+// Exit codes
+const (
+	exitCodeConfigLoadError = 2
+	exitCodeGenerateError   = 3
+)
+
+func main() {
+	// Initialize logger
+	logger := log.New(os.Stdout, "INFO: ", log.Ldate|log.Ltime|log.Lshortfile)
+
+	// Load the GraphQL configuration
+	cfg, err := loadGraphQLConfig()
+	if err != nil {
+		logger.Fatalf("Error loading GraphQL config: %v", err)
+	}
+
+	// Generate the GraphQL server code
+	err = generateGraphQLCode(cfg, logger)
+	if err != nil {
+		logger.Fatalf("Error generating GraphQL code: %v", err)
+	}
+}
+
+// loadGraphQLConfig loads the GraphQL configuration from default locations
+func loadGraphQLConfig() (*config.Config, error) {
+	cfg, err := config.LoadConfigFromDefaultLocations()
+	if err != nil {
+		return nil, fmt.Errorf("failed to load config: %w", err)
+	}
+	return cfg, nil
+}
+
+// generateGraphQLCode generates the GraphQL server code using the provided config
+func generateGraphQLCode(cfg *config.Config, logger *log.Logger) error {
+	// Attaching the mutation function onto modelgen plugin
+	p := modelgen.Plugin{
+		FieldHook: ValidationFieldHook,
+	}
+
+	// Generate the code using the API
+	err := api.Generate(cfg, api.ReplacePlugin(&p))
+	if err != nil {
+		return fmt.Errorf("code generation failed: %w", err)
+	}
+	logger.Println("GraphQL code generation successful")
+	return nil
+}
+
+// ValidationFieldHook is a custom hook for adding validation tags to fields based on directives
+func ValidationFieldHook(td *ast.Definition, fd *ast.FieldDefinition, f *modelgen.Field) (*modelgen.Field, error) {
+	// Look for the "validation" directive on the field
+	c := fd.Directives.ForName("validation")
+	if c != nil {
+		// Add validation tag based on the "format" argument in the directive
+		formatConstraint := c.Arguments.ForName("format")
+		if formatConstraint != nil {
+			// Use a format that avoids double quoting
+			f.Tag += fmt.Sprintf(` validate:"%s"`, formatConstraint.Value.Raw)
+		}
+	}
+	return f, nil
+}

backend/cmd/gqlgenerate/main_test.go

@@ -0,0 +1,61 @@
+package main
+
+import (
+	"log"
+	"os"
+	"testing"
+
+	"github.com/99designs/gqlgen/plugin/modelgen"
+	"github.com/vektah/gqlparser/v2/ast"
+)
+
+func TestLoadGraphQLConfig(t *testing.T) {
+	_, err := loadGraphQLConfig()
+	if err != nil {
+		t.Fatalf("Expected no error, got %v", err)
+	}
+}
+
+func TestGenerateGraphQLCode(t *testing.T) {
+	logger := log.New(os.Stdout, "INFO: ", log.Ldate|log.Ltime|log.Lshortfile)
+	cfg, err := loadGraphQLConfig()
+	if err != nil {
+		t.Fatalf("Failed to load config: %v", err)
+	}
+
+	err = generateGraphQLCode(cfg, logger)
+	if err != nil {
+		t.Fatalf("Expected no error, got %v", err)
+	}
+}
+
+func TestValidationFieldHook(t *testing.T) {
+	// Mock field definitions and directive
+	fd := &ast.FieldDefinition{
+		Directives: ast.DirectiveList{
+			{
+				Name: "validation",
+				Arguments: ast.ArgumentList{
+					{
+						Name: "format",
+						Value: &ast.Value{
+							Raw:  "email",
+							Kind: ast.StringValue,
+						},
+					},
+				},
+			},
+		},
+	}
+	f := &modelgen.Field{}
+
+	_, err := ValidationFieldHook(nil, fd, f)
+	if err != nil {
+		t.Fatalf("Expected no error, got %v", err)
+	}
+
+	expectedTag := ` validate:"email"`
+	if f.Tag != expectedTag {
+		t.Fatalf("Expected tag %v, got %v", expectedTag, f.Tag)
+	}
+}

backend/gqlgen.yml

@@ -85,3 +85,6 @@ models:
   Time:
     model:
       - github.com/99designs/gqlgen/graphql.Time
+directives:
+  validation:
+    skip_runtime: true

backend/graph/db/model.go

@@ -7,36 +7,36 @@ import (
 type User struct {
 	ID         int64       `gorm:"column:id;primaryKey"`
 	Name       string      `gorm:"column:name;not null" validate:"required,fl_name"`
-	Created    time.Time   `gorm:"column:created;autoCreateTime" validate:"required"`
-	Updated    time.Time   `gorm:"column:updated;autoCreateTime" validate:"required"`
+	Created    time.Time   `gorm:"column:created;autoCreateTime"`
+	Updated    time.Time   `gorm:"column:updated;autoCreateTime"`
 	CardGroups []Cardgroup `gorm:"many2many:cardgroup_users"`
 	Roles      []Role      `gorm:"many2many:user_roles"`
 }
 
 type Card struct {
 	ID           int64     `gorm:"column:id;primaryKey"`
-	Front        string    `gorm:"column:front;not null" validate:"required"`
-	Back         string    `gorm:"column:back;not null" validate:"required"`
-	ReviewDate   time.Time `gorm:"column:review_date;not null" validate:"required"`
-	IntervalDays int       `gorm:"column:interval_days;default:1;not null" validate:"required"`
-	Created      time.Time `gorm:"column:created;autoCreateTime" validate:"required"`
-	Updated      time.Time `gorm:"column:updated;autoCreateTime" validate:"required"`
-	CardGroupID  int64     `gorm:"column:cardgroup_id" validate:"required"`
+	Front        string    `gorm:"column:front;not null" validate:"required,min=1"`
+	Back         string    `gorm:"column:back;not null" validate:"required,min=1"`
+	ReviewDate   time.Time `gorm:"column:review_date;not null"`
+	IntervalDays int       `gorm:"column:interval_days;default:1;not null" validate:"gee=1"`
+	Created      time.Time `gorm:"column:created;autoCreateTime"`
+	Updated      time.Time `gorm:"column:updated;autoCreateTime"`
+	CardGroupID  int64     `gorm:"column:cardgroup_id"`
 }
 
 type Cardgroup struct {
 	ID      int64     `gorm:"column:id;primaryKey"`
-	Name    string    `gorm:"column:name;not null" validate:"required,fl_name"`
-	Created time.Time `gorm:"column:created;autoCreateTime" validate:"required"`
-	Updated time.Time `gorm:"column:updated;autoCreateTime" validate:"required"`
+	Name    string    `gorm:"column:name;not null" validate:"required,fl_name,min=1"`
+	Created time.Time `gorm:"column:created;autoCreateTime"`
+	Updated time.Time `gorm:"column:updated;autoCreateTime"`
 	Cards   []Card    `gorm:"foreignKey:CardGroupID"`
 	Users   []User    `gorm:"many2many:cardgroup_users"`
 }
 
 type Role struct {
 	ID      int64     `gorm:"column:id;primaryKey"`
-	Name    string    `gorm:"column:name;not null" validate:"required,fl_name"`
+	Name    string    `gorm:"column:name;not null" validate:"required,fl_name,min=1"`
 	Users   []User    `gorm:"many2many:user_roles"`
-	Created time.Time `gorm:"column:created;autoCreateTime" validate:"required"`
-	Updated time.Time `gorm:"column:updated;autoCreateTime" validate:"required"`
+	Created time.Time `gorm:"column:created;autoCreateTime"`
+	Updated time.Time `gorm:"column:updated;autoCreateTime"`
 }

backend/graph/directive.go

@@ -1 +1,51 @@
 package graph
+
+import (
+	"context"
+	"errors"
+	"regexp"
+
+	"github.com/99designs/gqlgen/graphql"
+)
+
+//gqlgen
+
+//
+// #directive @constraint(
+//#  minLength: Int,
+//#  maxLength: Int,
+//#  min: Int,
+//#  max: Int,
+//#  pattern: String) on INPUT_FIELD_DEFINITION
+
+func Constraint(ctx context.Context, obj interface{}, next graphql.Resolver, minLength *int, maxLength *int, min *int, max *int, pattern *string) (interface{}, error) {
+	val, err := next(ctx)
+	if err != nil {
+		return nil, err
+	}
+
+	switch v := val.(type) {
+	case string:
+		if minLength != nil && len(v) < *minLength {
+			return nil, errors.New("value is too short")
+		}
+		if maxLength != nil && len(v) > *maxLength {
+			return nil, errors.New("value is too long")
+		}
+		if pattern != nil {
+			matched, _ := regexp.MatchString(*pattern, v)
+			if !matched {
+				return nil, errors.New("value does not match pattern")
+			}
+		}
+	case int:
+		if min != nil && v < *min {
+			return nil, errors.New("value is too small")
+		}
+		if max != nil && v > *max {
+			return nil, errors.New("value is too large")
+		}
+	}
+
+	return val, nil
+}