Postgres very hard dynamic select statement with COALESCE - postgresql

Question

Having a table and data like this
CREATE TABLE solicitations
(
id SERIAL PRIMARY KEY,
name text
);
CREATE TABLE donations
(
id SERIAL PRIMARY KEY,
solicitation_id integer REFERENCES solicitations, -- can be null
created_at timestamp without time zone NOT NULL DEFAULT (now() at time zone 'utc'),
amount bigint NOT NULL DEFAULT 0
);
INSERT INTO solicitations (name) VALUES
('solicitation1'), ('solicitation2');
INSERT INTO donations (created_at, solicitation_id, amount) VALUES
('2018-06-26', null, 10), ('2018-06-26', 1, 20), ('2018-06-26', 2, 30),
('2018-06-27', null, 10), ('2018-06-27', 1, 20),
('2018-06-28', null, 10), ('2018-06-28', 1, 20), ('2018-06-28', 2, 30);
How to make solicitation id's dynamic in following select statement using only postgres???
SELECT
"created_at"
-- make dynamic this begins
, COALESCE("no_solicitation", 0) AS "no_solicitation"
, COALESCE("1", 0) AS "1"
, COALESCE("2", 0) AS "2"
-- make dynamic this ends
FROM crosstab(
$source_sql$
SELECT
created_at::date as row_id
, COALESCE(solicitation_id::text, 'no_solicitation') as category
, SUM(amount) as value
FROM donations
GROUP BY row_id, category
ORDER BY row_id, category
$source_sql$
, $category_sql$
-- parametrize with ids from here begins
SELECT unnest('{no_solicitation}'::text[] || ARRAY(SELECT DISTINCT id::text FROM solicitations ORDER BY id))
-- parametrize with ids from here ends
$category_sql$
) AS ct (
"created_at" date
-- make dynamic this begins
, "no_solicitation" bigint
, "1" bigint
, "2" bigint
-- make dynamic this ends
)
The select should return data like this
created_at no_solicitation 1 2
____________________________________
2018-06-26 10 20 30
2018-06-27 10 20 0
2018-06-28 10 20 30
The solicitation ids that should parametrize select are the same as in
SELECT unnest('{no_solicitation}'::text[] || ARRAY(SELECT DISTINCT id::text FROM solicitations ORDER BY id))
One can fiddle the code here

Answer 1

I decided to use json, which is much simpler then crosstab
WITH
all_solicitation_ids AS (
SELECT
unnest('{no_solicitation}'::text[] ||
ARRAY(SELECT DISTINCT id::text FROM solicitations ORDER BY id))
AS col
)
, all_days AS (
SELECT
-- TODO: compute days ad hoc, from min created_at day of donations to max created_at day of donations
generate_series('2018-06-26', '2018-06-28', '1 day'::interval)::date
AS col
)
, all_days_and_all_solicitation_ids AS (
SELECT
all_days.col AS created_at
, all_solicitation_ids.col AS solicitation_id
FROM all_days, all_solicitation_ids
ORDER BY all_days.col, all_solicitation_ids.col
)
, donations_ AS (
SELECT
created_at::date as created_at
, COALESCE(solicitation_id::text, 'no_solicitation') as solicitation_id
, SUM(amount) as amount
FROM donations
GROUP BY created_at, solicitation_id
ORDER BY created_at, solicitation_id
)
, donations__ AS (
SELECT
all_days_and_all_solicitation_ids.created_at
, all_days_and_all_solicitation_ids.solicitation_id
, COALESCE(donations_.amount, 0) AS amount
FROM all_days_and_all_solicitation_ids
LEFT JOIN donations_
ON all_days_and_all_solicitation_ids.created_at = donations_.created_at
AND all_days_and_all_solicitation_ids.solicitation_id = donations_.solicitation_id
)
SELECT
jsonb_object_agg(solicitation_id, amount) ||
jsonb_object_agg('date', created_at)
AS data
FROM donations__
GROUP BY created_at
which results
data
______________________________________________________________
{"1": 20, "2": 30, "date": "2018-06-28", "no_solicitation": 10}
{"1": 20, "2": 30, "date": "2018-06-26", "no_solicitation": 10}
{"1": 20, "2": 0, "date": "2018-06-27", "no_solicitation": 10}
Thought its not the same that I requested.
It returns only data column, instead of date, no_solicitation, 1, 2, ...., to do so I need to use json_to_record, but I dont know how to produce its as argument dynamically