Description
GORM Playground Link
Note: I attempted to create a GORM Playground Pull Request to reproduct this issue, but I encountered issues with the playground not functioning correctly. Therefore, I'm including a minimal reproducible example in this issue. I am including the following to ensure the issue is noticed: go-gorm/playground#1
Description
Summary:
When modifying a check constraint on a model field and running AutoMigrate, GORM does not update the existing check constraint in the database if a constraint with the same name already exists. This issue is observed with SQLite and may affect other database dialects as well.
Steps to Reproduce:
-
Set up the initial model with a check constraint and run
AutoMigrate:package main import ( "gorm.io/driver/sqlite" "gorm.io/gorm" "log" ) type User struct { ID uint Name string `gorm:"check:name_checker,name <> ''"` } func main() { db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{}) if err != nil { log.Fatalf("failed to connect to database: %v", err) } if err = db.AutoMigrate(&User{}); err != nil { log.Fatalf("failed to migrate: %v", err) } }
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Modify the check constraint in the model and run
AutoMigrateagain:package main import ( "gorm.io/driver/sqlite" "gorm.io/gorm" "log" ) type User struct { ID uint Name string `gorm:"check:name_checker,length(name) > 3"` } func main() { db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{}) if err != nil { log.Fatalf("failed to connect to database: %v", err) } if err = db.AutoMigrate(&User{}); err != nil { log.Fatalf("failed to migrate after modification: %v", err) } }
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Attempt to insert data that violates the new constraint but satisfies the old one:
package main import ( "fmt" "gorm.io/driver/sqlite" "gorm.io/gorm" "log" ) type User struct { ID uint Name string } func main() { db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{}) if err != nil { log.Fatalf("failed to connect to database: %v", err) } user := User{Name: "Hi"} // Length is 2, should violate the new constraint err = db.Create(&user).Error if err != nil { fmt.Printf("Expected error when inserting invalid data: %v\n", err) } else { fmt.Println("Unexpectedly inserted invalid data that should violate the new constraint") } user = User{Name: "Hello"} // Length is 5, should pass the new constraint err = db.Create(&user).Error if err != nil { fmt.Printf("Error when inserting valid data: %v\n", err) } else { fmt.Println("Successfully inserted valid data") } }
-
Observe the Output:
Unexpectedly inserted invalid data that should violate the new constraint Successfully inserted valid dataThis indicates that the check constraint was not updated in the database after modifying the model and running
AutoMigrateagain.
Expected Behavior:
- After modifying the check constraint and running
AutoMigrate, the existing constraint in the database should be updated to reflect the changes in the model. - Inserting data that violates the new constraint should result in an error.
Actual Behavior:
- The existing check constraint remains unchanged in the database, and the new constraint definition is not applied.
- Data that violates the new constraint but satisfies the old one can be inserted without errors.
Possible Cause:
- The
AutoMigratefunction checks for the existence of constraints by name and skips creation if the constraint exists, without verifying if the constraint definition has changed.
Environment:
- GORM version:
v1.25.12 - Go version:
go 1.23.0 - SQLite version: Using
gorm.io/driver/sqlitebut I was able to reproduce the same problem in postgres (I didn't try with other dialects but imagine the same issue exists) - OS: Windows 11
Additional Context:
- This issue may also affect other database dialects.
- Updating constraints is crucial for maintaining data integrity and ensuring that the database schema stays in sync with the application's data validation logic.
Workaround:
As a temporary workaround, manually drop the existing constraint before running AutoMigrate:
db.Migrator().DropConstraint(&User{}, "name_checker")
db.AutoMigrate(&User{})This forces the constraint to be recreated with the updated definition.
Possible Solution:
- Modify the
AutoMigratelogic to drop existing constraints with the same name before creating new ones. - Alternatively, compare the existing constraint definition with the new one and update it if they differ.
Note on GORM Playground:
I attempted to create a GORM Playground Pull Request to reproduce this issue as per the contribution guidelines, but I encountered issues with the playground not functioning correctly. It seems there might be problems with the playground at the moment, so I was unable to use it to demonstrate the issue. Therefore, I have included a minimal reproducible example directly in this issue.