Removing else-if-elseif.. in postgresql function - postgresql

Question

I would like to know if and there is some way to get rid code like this:
CREATE FUNCTION parent_function (json json, OUT response_status integer, OUT response json) RETURNS record
LANGUAGE plpgsql
AS $$
DECLARE
BEGIN
if <condition> then
<function_call1(json,response_status,response)>;
return;
elsif <condition> then
<function_call2(json,response_status,response)>;
return;
elsif <condition> then
<function_call3(json,response_status,response)>;
return;
end if;
END;
$$
I would like to move these conditions into separate functions where I would like based on what the function returns(there are some output parameters I need) terminate parent function without throwing exceptions and catch them in parent function?
What I would like to achive code like this:
CREATE FUNCTION parent_function (json json, OUT response_status integer, OUT response json) RETURNS record
LANGUAGE plpgsql
AS $$
DECLARE
BEGIN
<check_function1(json,response_status,response)>;
<check_function2(json,response_status,response)>;
<check_function3(json,response_status,response)>;
END;
$$
After calling message and output parameters set from function terminate further processing. Is it somehow posible?
Thanks,
Lukas

Answer 1

you want something like this example?
CREATE OR REPLACE FUNCTION aa_test_check1( IN test_value integer)
RETURNS TABLE( problem boolean , problemmessage text ) AS
$BODY$
begin
problem := false;
if $1 <10 then
problem := true;
problemmessage := 'integer is smaller than 10';
end if;
return next;
end;
$BODY$ LANGUAGE plpgsql IMMUTABLE;
CREATE OR REPLACE FUNCTION aa_test_check2( IN test_value integer)
RETURNS TABLE( problem boolean , problemmessage text ) AS
$BODY$
begin
problem := false;
if $1 >20 then
problem := true;
problemmessage := 'integer is greater than 20';
end if;
return next;
end;
$BODY$ LANGUAGE plpgsql IMMUTABLE;
CREATE OR REPLACE FUNCTION aa_test_check3( IN test_value integer)
RETURNS TABLE( problem boolean , problemmessage text ) AS
$BODY$
begin
problem := false;
if $1 =10 then
problem := true;
problemmessage := 'something is wrong, it cant be 10';
end if;
return next;
end;
$BODY$ LANGUAGE plpgsql IMMUTABLE;
CREATE OR REPLACE FUNCTION aa_test_main( IN test_value integer)
RETURNS TABLE( status_id integer , problemmessage text ) AS
$BODY$
declare
temp_problem boolean;
temp_problemmessage text;
begin
status_id := 0;
problemmessage := 'no problem, none at all';
select * from aa_test_check1($1)
into temp_problem, temp_problemmessage;
if temp_problem then
status_id := 1;
problemmessage := temp_problemmessage;
return next;
return;
end if;
select * from aa_test_check2($1)
into temp_problem, temp_problemmessage;
if temp_problem then
status_id := 2;
problemmessage := temp_problemmessage;
return next;
return;
end if;
select * from aa_test_check3($1)
into temp_problem, temp_problemmessage;
if temp_problem then
status_id := 3;
problemmessage := temp_problemmessage;
return next;
return;
end if;
return next;
end;
$BODY$
LANGUAGE plpgsql IMMUTABLE
COST 100
ROWS 100;
select * from aa_test_main(10)