How to Handle GORM Delete Errors When the Record Doesn\'t Exist?

Handling GORM Delete Errors

In Go, using the GORM library to perform database operations is common practice. One feature of GORM is the ability to delete records from a database. However, encountering errors during deletion is possible, and handling them appropriately is essential.

Consider the following function for deleting a category from a database using GORM:

<code class="go">func DeleteCategory(id uint) error {
    var category Category
    category.ID = id
    result := db.Delete(&category)
    fmt.Println("result.Error: ", result.Error)
    return result.Error
}</code>

This function attempts to delete a row in the database with the specified id. When a row is successfully deleted, GORM returns nil in result.Error. However, if an error occurs, GORM also returns nil in result.Error.

One particular scenario where this lack of error information can be problematic is when attempting to delete a row that doesn't exist. Since GORM considers this a successful operation (as no rows were affected), it returns nil in result.Error. In such cases, it may be more appropriate to return an error to indicate that the deletion attempt failed due to the record's absence.

To resolve this issue, you can check the RowsAffected field of the GORM result to determine whether any rows were deleted. If zero rows were affected, it means the record with the specified id does not exist in the database, and you can return an appropriate error message. Here's an updated version of the DeleteCategory function:

<code class="go">func DeleteCategory(id uint) error {
    c := Category{ID: id}

    db := db.Delete(&c)
    if db.Error != nil {
        return db.Error
    } else if db.RowsAffected < 1 {
        return fmt.Errorf("row with id=%d cannot be deleted because it doesn't exist", id)
    }

    return nil
}</code>

With this modification, the function will now correctly handle the case where the specified record doesn't exist and return an error with a clear message.

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