postgresql - Cast to user-defined data type in PostgreSQL

Question

I have created a data type called id which consists of two text values:

id(text, text)

I now need to cast values to this data type before they are inserted into my table. How would I go about doing this?

I created the type as follows:

CREATE TYPE ID AS(id text, source text);

Answer 1

好吧，要创建一个转换，您需要一个函数，该函数将一个类型的值作为您的输入并输出您希望转换为的类型（在本例中为“ID” - 如果我是你，我会更详细地命名它） . 你想从什么类型投射？

意识到不搞乱这一切，你应该可以根据这个页面使用你的类型。

只是.. SELECT ROW('foo','bar')::ID ;

Answer 2

你必须告诉 PostgreSQL 如何投射，CREATE CAST