How to cast to a user defined type in postgresql

Question

I have to create a table with some user defined types and insert data.

I tried this way.

create type type1 as (i int);
create function mycast(int) returns type1 as 'select $1;' language 'sql';
create cast (int as type1) with function mycast(int) as implicit;
create table table_type(t type1);
insert into table_type values(1::type1);

Now the values are getting inserted but wrapped in parenthesis, like this

select * from table_type;

  t  
--------
 (1)

(1 rows)

I believe there might be an error in my function. Can someone help. I wanted basically a function that returns the same output as my input (without any () ).

Thanks.

Peter Eisentraut · Accepted Answer · 2011-09-06 22:22:35Z

2

The type you defined is a composite type containing one attribute of type int. The text representation of a composite type is parentheses around the attribute list. But judging from your cast function (which is broken, because it returns a scalar and not a composite type), this isn't what you want at all. The best you could do is to define a domain like this:

create domain type1 as int;

Then you don't even need a cast.

answered Sep 6, 2011 at 22:22

Peter Eisentraut

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4 Comments

Grzegorz Szpetkowski Over a year ago

+1 for being faster. For reference CREATE DOMAIN

dspgsql Over a year ago

@Peter thanks,but I need to use create type itself. My requirement is to test the create type syntaxes and user defined types.

Peter Eisentraut Over a year ago

Then please write a question that describes what you are actually trying to do.

dspgsql Over a year ago

@Peter: I want to create a type, create a table using that type, and insert data into the table. thanks

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