How to make a loop structure out of an array in plpgsql? [duplicate] - postgresql

Question

In plpgsql, I want to get the array contents one by one from a two dimension array.
DECLARE
m varchar[];
arr varchar[][] := array[['key1','val1'],['key2','val2']];
BEGIN
for m in select arr
LOOP
raise NOTICE '%',m;
END LOOP;
END;
But the above code returns:
{{key1,val1},{key2,val2}}
in one line. I want to be able to loop over and call another function which takes parameters like:
another_func(key1,val1)

Answer 1

Since PostgreSQL 9.1
There is the convenient FOREACH which can loop over slices of arrays. The manual:
The target variable must be an array, and it receives successive
slices of the array value, where each slice is of the number of
dimensions specified by SLICE.
DO
$do$
DECLARE
m text[];
arr text[] := '{{key1,val1},{key2,val2}}'; -- array literal
BEGIN
FOREACH m SLICE 1 IN ARRAY arr
LOOP
RAISE NOTICE 'another_func(%,%)', m[1], m[2];
END LOOP;
END
$do$;
db<>fiddle here - with a function printing results, instead of DO
LANGUAGE plpgsql is the default for a DO statement so we can omit the declaration.
There is no difference between text[] and text[][] for the Postgres type system. See:
Initial array in function to aggregate multi-dimensional array
Postgres 9.0 or older
DO
$do$
DECLARE
arr text[] := array[['key1','val1'],['key2','val2']]; -- array constructor
BEGIN
FOR i IN array_lower(arr, 1) .. array_upper(arr, 1)
LOOP
RAISE NOTICE 'another_func(%,%)', arr[i][1], arr[i][2];
END LOOP;
END
$do$;