How to Persist Custom Set Data Types with GORM in Golang?

Persisting Custom Set Data Type Using GORM Golang

The provided code sample illustrates the challenge of persisting a custom Set data type using the GORM library in Golang. The custom type is thread unsafe and represents a set of strings. When attempting to persist a struct containing this Set type to MySQL using GORM, an error is encountered indicating that the Set type is invalid for MySQL.

To address this issue, it is necessary to implement certain methods in the custom Set type to enable database interaction. These methods include:

• Value(): Converts the Set type into a database-compatible value, such as a JSON-encoded string.
• Scan(): Populates the Set type from a database-retrieved value.

By implementing these methods, the GORM library can effectively handle the custom Set type during data persistence. Here's an example of how these methods can be implemented for the provided threadUnsafeSet:

type threadUnsafeSet map[interface{}]struct{}

func (set *threadUnsafeSet) Value() (driver.Value, error) {
    return json.Marshal(set), nil
}

func (set *threadUnsafeSet) Scan(value interface{}) error {
    switch value := value.(type) {
    case []byte:
        return json.Unmarshal(value, set)
    }
    return errors.New("unrecognized value type")
}

Note that the Value() method converts the threadUnsafeSet to a JSON-encoded string, while the Scan() method unmarshals the JSON string back into the threadUnsafeSet.

With these methods in place, the custom Set data type can be used effectively with GORM for data persistence. It is important to implement the Value() and Scan() methods according to the specific requirements of the database being used.

The above is the detailed content of How to Persist Custom Set Data Types with GORM in Golang?. For more information, please follow other related articles on the PHP Chinese website!