JSONB Data Handling in Gorm
Managing JSONB data in Postgres with Gorm can pose challenges, particularly when working with a slice of strings. Here's a detailed examination of the options available:
Using postgres.Jsonb:
Gorm provides a specific type, postgres.Jsonb, designed for JSONB manipulation. While this method offers a straightforward approach, it may not be ideal for scenarios where you prefer to avoid using the Gorm-specific type.
Slice of Strings:
When defining a Go struct with a slice of strings and attempting to map it as a JSONB object, Gorm may encounter difficulties. If you choose this approach, you'll need to explicitly specify the sql and json tags as shown below:
type User struct { gorm.Model Data []string `sql:"type:jsonb" json:"data"` }
However, this approach may trigger a panic during AutoMigrate execution.
Nested Struct:
To bypass the panic issue, you can wrap the slice of strings within a nested struct:
type User struct { gorm.Model Data struct { NestedData []string } `sql:"type:jsonb" json:"data"` }
While this technique prevents the crash, it might not create the intended column in Postgres.
Alternative Solution with pgtype.JSONB:
A preferred approach involves utilizing the pgtype.JSONB type available in pgx, Gorm's underlying driver. This method eliminates the need for custom code and allows for manipulation of any JSONB type beyond string slices.
Here's an example of how to use pgtype.JSONB:
type User struct { gorm.Model Data pgtype.JSONB `gorm:"type:jsonb;default:'[]';not null"` }
To retrieve data from the database:
u := User{} db.Find(&u) var data []string _ = u.Data.AssignTo(&data)
To update data in the database:
u := User{} _ = u.Data.Set([]string{"abc", "def"}) db.Updates(&u)
By leveraging this approach, you can effectively manage JSONB data in Gorm without using the postgres.Jsonb type.
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