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sqldiffupdater

The sqldiffupdater.Generate() is a Golang function that generates an SQL update statement based on the comparison of the properties of two objects, newvar and oldvar. The function takes three arguments: tableName, newvar, and oldvar.

The tableName argument is a string that represents the name of the database table that the update statement will be executed against. The newvar and oldvar arguments are the new and old versions of the object that will be compared.

The function uses reflection to get the names and values of the properties of the newvar and oldvar objects, and generates an SQL update statement based on the differences between the two objects. The function checks that the newvar and oldvar objects have the same type, and that they have an Id field as a primary key.

The function returns a string representing the generated SQL update statement, a map containing the values of the changed properties, and an error if one occurs during the execution of the function.

Parameters

• tableName (string): The name of the database table that the update statement will be executed against.
• newvar (interface{}): The new version of the object that will be compared.
• oldvar (interface{}): The old version of the object that will be compared.

Returns

• string: The generated SQL update statement.
• map[string]interface{}: A map containing the values of the changed properties.
• error: An error if one occurs during the execution of the function.

Example

type User struct {
    Id        int
    FirstName string
    LastName  string
    Email     string
}

newUser := User{Id: 1, FirstName: "John", LastName: "Doe", Email: "johndoe@example.com"}
oldUser := User{Id: 1, FirstName: "Jane", LastName: "Doe", Email: "janedoe@example.com"}

sql, values, err := Generate("users", newUser, oldUser)
if err != nil {
    // handle error
}

// sql: "UPDATE users SET FirstName=:FirstName, Email=:Email WHERE Id=:Id"
// here changed only FirstName and Email
// values: map[string]interface{}{"FirstName": "John", "Email": "johndoe@example.com", "Id": 1}
// db : your sql=db provider
err = db.Exec(sql, values)
if err != nil {
    // handle error
}

Documentation

Index

• func Generate(tableName string, newvar interface{}, oldvar interface{}) (string, map[string]interface{}, error)

Functions

func Generate

func Generate(tableName string, newvar interface{}, oldvar interface{}) (string, map[string]interface{}, error)