refactor: update interface contract and applies some fixes

internal/repository/base_repository.go

@@ -10,7 +10,7 @@ type baseRepository[T any] struct {
 	tableName string
 }
 
-func NewBaseRepository[T any](db *sql.DB, tableName string) Repository[T] {
+func NewBaseRepository[T any](db *sql.DB, tableName string) *baseRepository[T] {
 	return &baseRepository[T]{
 		db:        db,
 		tableName: tableName,
@@ -25,14 +25,34 @@ func (r *baseRepository[T]) GetDB() *sql.DB {
 	return r.db
 }
 
+func (r *baseRepository[T]) GetAll() ([]T, error) {
+	query := r.BuildQuery("SELECT * FROM %s ORDER BY id DESC")
+
+	rows, err := r.db.Query(query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	entities := make([]T, 0)
+	rowsErr := ScanRows(rows, &entities)
+
+	if rowsErr != nil {
+		return nil, err
+	}
+
+	return entities, nil
+}
+
 func (r *baseRepository[T]) GetByID(id int) (*T, error) {
 	var entity T
 
 	query := r.BuildQuery("SELECT * FROM %s WHERE id = ?")
-	err := r.db.QueryRow(
+	row := r.db.QueryRow(
 		query,
 		id,
-	).Scan(entity)
+	)
+	err := scanRow(row, &entity)
 
 	if err != nil {
 		if err == sql.ErrNoRows {
@@ -44,33 +64,8 @@ func (r *baseRepository[T]) GetByID(id int) (*T, error) {
 	return &entity, nil
 }
 
-func (r *baseRepository[T]) GetAll() ([]T, error) {
-	query := r.BuildQuery("SELECT * FROM %s ORDER BY id DESC")
-
-	rows, err := r.db.Query(query)
-	if err != nil {
-		return nil, err
-	}
-	defer rows.Close()
-
-	entities := make([]T, 0)
-	for rows.Next() {
-		var entity T
-		if err := rows.Scan(entity); err != nil {
-			return nil, err
-		}
-		entities = append(entities, entity)
-	}
-
-	if err = rows.Err(); err != nil {
-		return nil, err
-	}
-
-	return entities, nil
-}
-
 func (r *baseRepository[T]) Delete(id int) (int64, error) {
-	query := r.BuildQuery("DELETE %s WHERE id = ? LIMIT 1")
+	query := r.BuildQuery("DELETE FROM %s WHERE id = ?")
 	res, err := r.db.Exec(query, id)
 	if err != nil {
 		return 0, err

internal/repository/contact_repository.go

@@ -2,6 +2,7 @@ package repository
 
 import (
 	"database/sql"
+	"fmt"
 
 	"gitea.gabilandia.com/gabdlr/agenda-web-go/internal/models"
 )
@@ -10,7 +11,7 @@ type ContactRepository struct {
 	baseRepository[models.Contact]
 }
 
-func NewContactRepository(db *sql.DB) *ContactRepository {
+func NewContactRepository(db *sql.DB) Repository[models.Contact] {
 	return &ContactRepository{
 		baseRepository[models.Contact]{
 			db:        db,
@@ -38,20 +39,45 @@ func (r *ContactRepository) Create(contact *models.Contact) (int64, error) {
 	return id, nil
 }
 
-func (r *ContactRepository) Update(contact *models.Contact) (int64, error) {
-	query := r.BuildQuery("UPDATE %s SET name = ?, company = ?, phone = ? WHERE id = ?")
-	result, err := r.db.Exec(query,
-		contact.Name, contact.Company, contact.Phone, contact.ID,
+func (r *ContactRepository) Update(contact *models.Contact) error {
+	query := r.BuildQuery("UPDATE %s SET")
+	fieldsToUpdate := make([]string, 0, 4)
+	fields := make([]any, 0)
+
+	if contact.Name != "" {
+		fieldsToUpdate = append(fieldsToUpdate, "name")
+		fields = append(fields, &contact.Name)
+	}
+
+	if contact.Company != "" {
+		fieldsToUpdate = append(fieldsToUpdate, "company")
+		fields = append(fields, &contact.Company)
+	}
+
+	if contact.Phone != "" {
+		fieldsToUpdate = append(fieldsToUpdate, "phone")
+		fields = append(fields, &contact.Phone)
+	}
+
+	fields = append(fields, &contact.ID)
+
+	fieldsToUpdatelen := len(fieldsToUpdate)
+	for i, field := range fieldsToUpdate {
+		query += fmt.Sprintf(" %s = ?", field)
+		if i != fieldsToUpdatelen-1 {
+			query += ","
+		}
+	}
+
+	query += " WHERE id = ?"
+
+	_, err := r.db.Exec(query,
+		fields...,
 	)
 
 	if err != nil {
-		return 0, err
+		return err
 	}
 
-	rowsAffected, err := result.RowsAffected()
-	if err != nil {
-		return 0, err
-	}
-
-	return rowsAffected, nil
+	return nil
 }

internal/repository/interfaces.go

@@ -1,8 +1,9 @@
 package repository
 
 type Repository[T any] interface {
-	BuildQuery(s string) string
-	GetByID(id int) (*T, error)
-	GetAll() ([]T, error)
+	Create(T *T) (int64, error)
 	Delete(id int) (int64, error)
+	GetAll() ([]T, error)
+	GetByID(id int) (*T, error)
+	Update(contact *T) error
 }

internal/repository/scanner_helper.go

@@ -0,0 +1,55 @@
+package repository
+
+import (
+	"database/sql"
+	"fmt"
+	"reflect"
+)
+
+func scanRow(row *sql.Row, dest any) error {
+	destValue := reflect.ValueOf(dest).Elem()
+	fields := make([]any, destValue.NumField())
+
+	for i := 0; i < destValue.NumField(); i++ {
+		fields[i] = destValue.Field(i).Addr().Interface()
+	}
+
+	return row.Scan(fields...)
+}
+
+func ScanRows(rows *sql.Rows, destSlice any) error {
+	sliceValue := reflect.ValueOf(destSlice)
+	if sliceValue.Kind() != reflect.Pointer || sliceValue.Elem().Kind() != reflect.Slice {
+		return fmt.Errorf("destSlice must be a pointer to a slice")
+	}
+
+	sliceElem := sliceValue.Elem()
+	structType := sliceElem.Type().Elem()
+
+	for rows.Next() {
+		newStruct := reflect.New(structType).Elem()
+
+		fields := make([]any, newStruct.NumField())
+		for i := 0; i < newStruct.NumField(); i++ {
+			fields[i] = newStruct.Field(i).Addr().Interface()
+		}
+
+		if err := rows.Scan(fields...); err != nil {
+			return err
+		}
+
+		sliceElem.Set(reflect.Append(sliceElem, newStruct))
+	}
+
+	return rows.Err()
+}
+
+func GetStructFieldsPtr(object any) []any {
+	destValue := reflect.ValueOf(object).Elem()
+	fields := make([]any, destValue.NumField())
+
+	for i := 0; i < destValue.NumField(); i++ {
+		fields[i] = destValue.Field(i).Addr().Interface()
+	}
+	return fields
+}