Improve composer management

src/models/sheet.go

@@ -10,11 +10,12 @@ import (
 type Sheet struct {
 	Uuid        uuid.UUID      `json:"uuid" gorm:"type:uuid;primaryKey"`
 	Title       string         `json:"title" gorm:"not null"`
-	Composer    string         `json:"composer"`
 	Description string         `json:"description"`
 	FilePath    string         `json:"file_path" gorm:"not null"`
 	FileSize    int64          `json:"file_size"`
 	FileHash    uint64         `json:"file_hash"`
+	ComposerId  uuid.UUID      `json:"composer_id"`
+	Composer    Composer       `json:"composer" gorm:"foreignKey:ComposerId"`
 	CreatedAt   time.Time      `json:"created_at"`
 	UpdatedAt   time.Time      `json:"updated_at"`
 	DeletedAt   gorm.DeletedAt `json:"-" gorm:"index"`