Function: Use text/varchar parameter as a query - postgresql

Question

I have a query that I use in different parts of a system. Now I want to make a function wherein it accepts a text to be used as a query, I'm not even sure if this is possible. However, I want to know if there's a possible workaround for this.
What I want to achieve is a function that returns a table and accepts a text/varchar that could be used as a query.
Here's what I have, I have a query that is kind of a "base query" that can have different data based on the given CTE which is named:
data_table
refer to the function and its usage below - this is mostly abstract but imo this should be enough.
CREATE OR REPLACE FUNCTION func(
data_query TEXT
)
RETURNS TABLE
(
id BIGINT,
random_text varchar
)
LANGUAGE plpgsql
AS $function$
BEGIN
RETURN QUERY
with data_table AS (
data_query
), another_data_table AS (
SELECT
*
FROM my_data
)
SELECT
d.id,
ad.random_text
FROM data_table d
INNER JOIN another_data_table ad
ON ad.ref_id = d.id;
END; $function$;
usage:
SELECT * FROM func('SELECT * FROM my_data_table');
SELECT * FROM func('SELECT * FROM my_second_data_table');

Answer 1

Instead of passing the query, you may pass the table name and access it dyamically in your query using EXECUTE format
CREATE OR REPLACE FUNCTION func(
table_name_in TEXT
)
RETURNS TABLE
(
id BIGINT,
random_text varchar
)
LANGUAGE plpgsql
AS $function$
BEGIN
RETURN QUERY EXECUTE format (
'SELECT
d.id :: bigint,
ad.random_text :: varchar
FROM %I d
INNER JOIN my_data ad
ON ad.ref_id = d.id', table_name_in );
END
$function$;
usage:
SELECT * FROM func('my_data_table');
SELECT * FROM func('my_second_data_table');