What's the difference between Gorm Save and Update?

In Golang's ORM library Gorm, the Save and Update methods are used to handle saving and updating records in the database, but they have some key differences:

1. Save Method

The Save method in Gorm is used to save all fields of a model, regardless of whether it is a new record or an existing record. If it is a new record (not yet present in the database), it inserts; if it is an existing record (already present in the database), it updates all fields.

Example:

go
db.Save(&user)

Here, regardless of whether user is newly created or loaded from the database, all fields are saved or updated to the database.

2. Update Method

Unlike Save, the Update method is used to update one or more specific fields, rather than all fields. This is particularly useful when only a few fields of the model need modification, allowing precise control over which fields to update and avoiding unintended data overwrites.

Example:

go
// Update a single field
db.Model(&user).Update("name", "New Name")
// Update multiple fields
db.Model(&user).Updates(User{Name: "New Name", Age: 29})

In the above examples, the Update method updates specific fields, such as name or both name and age fields simultaneously.

Key Differences Summary:

• Full-field update vs. Partial-field update: Save updates all fields of the model, while Update allows specifying only partial fields to be updated.
• Use cases: If you need to update all information of a record, Save is more suitable; if you only need to modify partial information, Update is more efficient, reducing data transfer and potentially avoiding concurrency issues.

By understanding these differences, developers can choose the most appropriate method for database operations based on actual needs, resulting in clear and efficient code.