The error "cannot affect row a second time" occurs in GORM when trying to upsert duplicate associations. In other words, the error occurs when you try to insert an already existing record into the database.
To resolve this issue, you can use the OnConflict clause in your GORM query to handle upserts in a bulk manner. Here's an example of how you can use the OnConflict clause in GORM to upsert records in a bulk manner:
vbnet
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db.Set("gorm:insert_option", "ON CONFLICT DO NOTHING").Create(&associations).Error
The ON CONFLICT DO NOTHING option in the insert_option tells GORM to not insert the record if it already exists in the database.
Alternatively, you can also handle duplicated associations by first checking if the association already exists in the database and only inserting it if it doesn't. Here's an example:
go
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for _, association := range associations {
var existingAssociation Association
db.Where(Association{Name: association.Name}).FirstOrCreate(&existingAssociation)
association.ID = existingAssociation.ID
}
This code first checks if the association with the given name exists in the database. If it does, it updates the association.ID with the existing association's ID. If it doesn't, it inserts a new association into the database.
You can also handle duplicated associations by using a unique constraint on the relevant fields in your database. When a duplicate association is inserted, the database will return an error, and you can handle it in your code. Here's an example:
go
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for _, association := range associations {
db.Create(&association).Error
if db.Error != nil {
if strings.Contains(db.Error.Error(), "duplicate key value") {
// Handle the error, for example, by updating the existing association instead of inserting a new one
} else {
// Handle other errors
}
}
}
In this example, the code iterates through the associations slice and inserts each association into the database. If a duplicate key error occurs, it checks the error message and handles it accordingly.
By using one of the above methods, you can handle duplicated associations in GORM and avoid the cannot affect row a second time error.