Destructive operations

They are the operations that drop tables, columns, indexes, constraints, and so on.

• DropCheckConstraint(tableName schema.TableName, constraintName string, opts ...schema.DropCheckConstraintOptions)

• DropColumn(tableName schema.TableName, columnName string, opts ...schema.DropColumnOptions)

• DropExtension(name string, opts ...schema.DropExtensionOptions)

• DropForeignKeyConstraint(fromTable, toTable schema.TableName, opts ...schema.DropForeignKeyConstraintOptions)

• DropIndex(table schema.TableName, columns []string, opts ...schema.DropIndexOptions)

• DropPrimaryKeyConstraint(tableName schema.TableName, opts ...schema.DropPrimaryKeyConstraintOptions)

• DropTable(tableName schema.TableName, opts ...schema.DropTableOptions)

• RemoveVersion(version string)

• RenameColumn(tableName schema.TableName, oldColumnName, newColumnName string)

• DropEnum(name string, opts ...schema.DropEnumOptions)

Usually you will use these functions in the down function of a migration, but you can use them in the up function too. If you want to have the reverse operation of a destructive operation, you can use the reversible options.

Example:

p.DropTable("users", schema.DropTableOptions{
	Reversible: &TableOption{
        schema.TableName: "users",
        PostgresTableDefinition: Innerschema.Tablefunc(t *PostgresTableDef) {
            t.Serial("id")
            t.String("name")
        }),
}})

In that case, if you are in a change function in your migration, the library will at the up operation drop the table users and at the down operation re-create the table users with the columns id and name.