diff --git a/src/handlers/sheets.go b/src/handlers/sheets.go
index 4dc9d1c..770881c 100644
--- a/src/handlers/sheets.go
+++ b/src/handlers/sheets.go
@@ -33,7 +33,24 @@ func UploadSheet(c *gin.Context) {
 		return
 	}
 
-	composer := c.PostForm("composer")
+	composerUUIDStr := c.PostForm("composer_uuid")
+	if composerUUIDStr == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Composer UUID is required"})
+		return
+	}
+
+	composerUUID, err := uuid.Parse(composerUUIDStr)
+	if err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Invalid composer UUID"})
+		return
+	}
+
+	var composer models.Composer
+	if err := database.DB.First(&composer, composerUUID).Error; err != nil {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "Composer not found"})
+		return
+	}
+
 	description := c.PostForm("description")
 
 	// Get uploaded file
@@ -91,11 +108,11 @@ func UploadSheet(c *gin.Context) {
 	sheet := models.Sheet{
 		Uuid:        *uuid,
 		Title:       title,
-		Composer:    composer,
 		Description: description,
 		FilePath:    filePath,
 		FileSize:    fileInfo.Size(),
 		FileHash:    fileHash,
+		ComposerID:  composer.Uuid,
 		CreatedAt:   time.Now(),
 		UpdatedAt:   time.Now(),
 	}
@@ -116,7 +133,7 @@ func UploadSheet(c *gin.Context) {
 func ListSheets(c *gin.Context) {
 	var sheets []models.Sheet
 
-	if err := database.DB.Find(&sheets).Error; err != nil {
+	if err := database.DB.Preload("Composer").Find(&sheets).Error; err != nil {
 		c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to fetch sheets"})
 		return
 	}
diff --git a/src/models/sheet.go b/src/models/sheet.go
index 080db2d..c5dce69 100644
--- a/src/models/sheet.go
+++ b/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"`