Evaluate dynamic condition in PL/pgSQL using EXECUTE
I have a function that needs to dynamically validate the input based on the value type. It does this by finding the constraint in another table, but for simplicity I provide the constraint as well in the function below.
This other table contains (value_type, value_constraint), where value_constraint is a text field that contains e.g. value::int > 0. I need to dynamically check this constraint within my insert function. I was trying to do that using EXECUTE as seen below, but it's not working.
How do I dynamically execute a condition statement and get the value as a boolean into v_successful_insert?
CREATE OR REPLACE FUNCTION insert_value(p_value_type text, p_value_constraint text, p_value text) RETURNS boolean
AS $$
DECLARE
v_successful_insert bool;
BEGIN
EXECUTE p_value_constraint INTO v_successful_insert;
IF v_successful_insert THEN
INSERT INTO my_table (value_type, value)
VALUES (p_value_type, p_value);
END IF;
RETURN v_successful_insert;
END;
$$
LANGUAGE plpgsql volatile;
The code is run on Postgresql 10.6.
sql postgresql plpgsql
asked Nov 15 '18 at 0:15
pirpir
1,11643063
add a comment |
I have a function that needs to dynamically validate the input based on the value type. It does this by finding the constraint in another table, but for simplicity I provide the constraint as well in the function below.
This other table contains (value_type, value_constraint), where value_constraint is a text field that contains e.g. value::int > 0. I need to dynamically check this constraint within my insert function. I was trying to do that using EXECUTE as seen below, but it's not working.
How do I dynamically execute a condition statement and get the value as a boolean into v_successful_insert?
CREATE OR REPLACE FUNCTION insert_value(p_value_type text, p_value_constraint text, p_value text) RETURNS boolean
AS $$
DECLARE
v_successful_insert bool;
BEGIN
EXECUTE p_value_constraint INTO v_successful_insert;
IF v_successful_insert THEN
INSERT INTO my_table (value_type, value)
VALUES (p_value_type, p_value);
END IF;
RETURN v_successful_insert;
END;
$$
LANGUAGE plpgsql volatile;
The code is run on Postgresql 10.6.
sql postgresql plpgsql
asked Nov 15 '18 at 0:15
pirpir
1,11643063
add a comment |
I have a function that needs to dynamically validate the input based on the value type. It does this by finding the constraint in another table, but for simplicity I provide the constraint as well in the function below.
This other table contains (value_type, value_constraint), where value_constraint is a text field that contains e.g. value::int > 0. I need to dynamically check this constraint within my insert function. I was trying to do that using EXECUTE as seen below, but it's not working.
How do I dynamically execute a condition statement and get the value as a boolean into v_successful_insert?
CREATE OR REPLACE FUNCTION insert_value(p_value_type text, p_value_constraint text, p_value text) RETURNS boolean
AS $$
DECLARE
v_successful_insert bool;
BEGIN
EXECUTE p_value_constraint INTO v_successful_insert;
IF v_successful_insert THEN
INSERT INTO my_table (value_type, value)
VALUES (p_value_type, p_value);
END IF;
RETURN v_successful_insert;
END;
$$
LANGUAGE plpgsql volatile;
The code is run on Postgresql 10.6.
sql postgresql plpgsql
asked Nov 15 '18 at 0:15
pirpir
1,11643063
I have a function that needs to dynamically validate the input based on the value type. It does this by finding the constraint in another table, but for simplicity I provide the constraint as well in the function below.
This other table contains (value_type, value_constraint), where value_constraint is a text field that contains e.g. value::int > 0. I need to dynamically check this constraint within my insert function. I was trying to do that using EXECUTE as seen below, but it's not working.
How do I dynamically execute a condition statement and get the value as a boolean into v_successful_insert?
CREATE OR REPLACE FUNCTION insert_value(p_value_type text, p_value_constraint text, p_value text) RETURNS boolean
AS $$
DECLARE
v_successful_insert bool;
BEGIN
EXECUTE p_value_constraint INTO v_successful_insert;
IF v_successful_insert THEN
INSERT INTO my_table (value_type, value)
VALUES (p_value_type, p_value);
END IF;
RETURN v_successful_insert;
END;
$$
LANGUAGE plpgsql volatile;
The code is run on Postgresql 10.6.
sql postgresql plpgsql
sql postgresql plpgsql
asked Nov 15 '18 at 0:15
pirpir
1,11643063
asked Nov 15 '18 at 0:15
pirpir
1,11643063
asked Nov 15 '18 at 0:15
pirpir
1,11643063
asked Nov 15 '18 at 0:15
pirpir
1,11643063
asked Nov 15 '18 at 0:15
pirpir
1,11643063
1,11643063
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
You need to do a SELECT in the execute. For example:
DO $$
DECLARE
p_value TEXT := 'x';
p_value_constraint TEXT := '::int > 0';
result BOOLEAN;
BEGIN
BEGIN
EXECUTE 'SELECT $1' || p_value_constraint
INTO result
USING p_value;
EXCEPTION
WHEN INVALID_TEXT_REPRESENTATION THEN
result := FALSE;
END;
RAISE NOTICE '%', result;
END $$
Prints FALSE
answered Nov 15 '18 at 0:27
404404
3,2051827
Amazing, thanks. Is it possible to make an error in the EXECUTE step not cause issues, but just makev_successful_insertbecome false? E.g. a try/except of sorts.
– pir
Nov 15 '18 at 0:31
1
@pir Yep, updated answer with exception handling.
– 404
Nov 15 '18 at 0:34
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
You need to do a SELECT in the execute. For example:
DO $$
DECLARE
p_value TEXT := 'x';
p_value_constraint TEXT := '::int > 0';
result BOOLEAN;
BEGIN
BEGIN
EXECUTE 'SELECT $1' || p_value_constraint
INTO result
USING p_value;
EXCEPTION
WHEN INVALID_TEXT_REPRESENTATION THEN
result := FALSE;
END;
RAISE NOTICE '%', result;
END $$
Prints FALSE
answered Nov 15 '18 at 0:27
404404
3,2051827
Amazing, thanks. Is it possible to make an error in the EXECUTE step not cause issues, but just makev_successful_insertbecome false? E.g. a try/except of sorts.
– pir
Nov 15 '18 at 0:31
1
@pir Yep, updated answer with exception handling.
– 404
Nov 15 '18 at 0:34
add a comment |
You need to do a SELECT in the execute. For example:
DO $$
DECLARE
p_value TEXT := 'x';
p_value_constraint TEXT := '::int > 0';
result BOOLEAN;
BEGIN
BEGIN
EXECUTE 'SELECT $1' || p_value_constraint
INTO result
USING p_value;
EXCEPTION
WHEN INVALID_TEXT_REPRESENTATION THEN
result := FALSE;
END;
RAISE NOTICE '%', result;
END $$
Prints FALSE
answered Nov 15 '18 at 0:27
404404
3,2051827
Amazing, thanks. Is it possible to make an error in the EXECUTE step not cause issues, but just makev_successful_insertbecome false? E.g. a try/except of sorts.
– pir
Nov 15 '18 at 0:31
1
@pir Yep, updated answer with exception handling.
– 404
Nov 15 '18 at 0:34
add a comment |
You need to do a SELECT in the execute. For example:
DO $$
DECLARE
p_value TEXT := 'x';
p_value_constraint TEXT := '::int > 0';
result BOOLEAN;
BEGIN
BEGIN
EXECUTE 'SELECT $1' || p_value_constraint
INTO result
USING p_value;
EXCEPTION
WHEN INVALID_TEXT_REPRESENTATION THEN
result := FALSE;
END;
RAISE NOTICE '%', result;
END $$
Prints FALSE
answered Nov 15 '18 at 0:27
404404
3,2051827
You need to do a SELECT in the execute. For example:
DO $$
DECLARE
p_value TEXT := 'x';
p_value_constraint TEXT := '::int > 0';
result BOOLEAN;
BEGIN
BEGIN
EXECUTE 'SELECT $1' || p_value_constraint
INTO result
USING p_value;
EXCEPTION
WHEN INVALID_TEXT_REPRESENTATION THEN
result := FALSE;
END;
RAISE NOTICE '%', result;
END $$
Prints FALSE
answered Nov 15 '18 at 0:27
404404
3,2051827
edited Nov 15 '18 at 0:34
answered Nov 15 '18 at 0:27
404404
3,2051827
answered Nov 15 '18 at 0:27
404404
3,2051827
answered Nov 15 '18 at 0:27
404404
3,2051827
3,2051827
Amazing, thanks. Is it possible to make an error in the EXECUTE step not cause issues, but just makev_successful_insertbecome false? E.g. a try/except of sorts.
– pir
Nov 15 '18 at 0:31
1
@pir Yep, updated answer with exception handling.
– 404
Nov 15 '18 at 0:34
add a comment |
Amazing, thanks. Is it possible to make an error in the EXECUTE step not cause issues, but just makev_successful_insertbecome false? E.g. a try/except of sorts.
– pir
Nov 15 '18 at 0:31
1
@pir Yep, updated answer with exception handling.
– 404
Nov 15 '18 at 0:34
Amazing, thanks. Is it possible to make an error in the EXECUTE step not cause issues, but just make
v_successful_insert become false? E.g. a try/except of sorts.– pir
Nov 15 '18 at 0:31
Amazing, thanks. Is it possible to make an error in the EXECUTE step not cause issues, but just make
v_successful_insert become false? E.g. a try/except of sorts.– pir
Nov 15 '18 at 0:31
1
1
@pir Yep, updated answer with exception handling.
– 404
Nov 15 '18 at 0:34
@pir Yep, updated answer with exception handling.
– 404
Nov 15 '18 at 0:34
add a comment |
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