无法在自定义类型的列上使用替换功能

Question

In order to enforce some constraints, our devs use a custom type for a type/factor column.

Custom type defined as such and includes both the old and new value:

create type custom_type as enum ('Value1', 'Value2', 'Value3', 'OldValue', 'NewValue');

I'm trying to update some values in a table like so:

UPDATE table SET column = replace(column, 'OldValue'::custom_type, 'NewValue'::custom_type);

However am receiving the following error:

[2019-04-11 16:37:42] [42883] ERROR: function replace(column, custom_type, custom_type) does not exist
[2019-04-11 16:37:42] Hint: No function matches the given name and argument types. You might need to add explicit type casts.

I'm guessing that this is going to require defining a custom "replace" function in order to handle the types or is there a way that I can handle this by just casting.

For reference this is PostgreSQL 11.2

Answer 1

replace() works on strings, not on enums. You can do what you appently want with an UPDATE with a WHERE clause.

UPDATE table
       SET column = 'NewValue'::custom_type
       WHERE column = 'OldValue'::custom_type;