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Boolean DB type casting extension #980

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merged 2 commits into from
Jan 18, 2022
Merged

Boolean DB type casting extension #980

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e5e950c
Add more options for casting to boolean type
mathemancer Jan 17, 2022
282aee0
add tests for new boolean casts
mathemancer Jan 17, 2022
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8 changes: 6 additions & 2 deletions db/tests/types/operations/test_cast.py
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Original file line number Diff line number Diff line change
Expand Up @@ -531,7 +531,9 @@
},
BOOLEAN: {
VALID: [
("true", True), ("false", False), ("t", True), ("f", False)
("true", True), ("false", False), ("t", True), ("f", False),
("yes", True), ("y", True), ("no", False), ("n", False),
("on", True), ("off", False),
],
INVALID: ["cat"],
},
Expand Down Expand Up @@ -670,7 +672,9 @@
},
BOOLEAN: {
VALID: [
("true", True), ("false", False), ("t", True), ("f", False)
("true", True), ("false", False), ("t", True), ("f", False),
("yes", True), ("y", True), ("no", False), ("n", False),
("on", True), ("off", False),
],
INVALID: ["cat"],
},
Expand Down
73 changes: 48 additions & 25 deletions db/types/operations/cast.py
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Original file line number Diff line number Diff line change
Expand Up @@ -304,8 +304,10 @@ def assemble_function_creation_sql(argument_type, target_type, function_body):

def get_cast_function_name(target_type):
"""
Some casting functions change postgres config parameters for the transaction they are run on like cast function for casting different data type to timestamp with timezone,
So they used be in an isolated transaction
Some casting functions change postgres config parameters for the
transaction they are run on like cast function for casting different
data type to timestamp with timezone, So they used be in an isolated
transaction
"""
unqualified_type_name = target_type.split('.')[-1].lower()
if '(' in unqualified_type_name:
Expand Down Expand Up @@ -352,8 +354,16 @@ def _get_text_to_boolean_cast_str():
DECLARE
istrue {BOOLEAN};
BEGIN
SELECT lower($1)='t' OR lower($1)='true' OR $1='1' INTO istrue;
IF istrue OR lower($1)='f' OR lower($1)='false' OR $1='0' THEN
SELECT
$1='1' OR lower($1) = 'on'
OR lower($1)='t' OR lower($1)='true'
OR lower($1)='y' OR lower($1)='yes'
INTO istrue;
IF istrue
OR $1='0' OR lower($1) = 'off'
OR lower($1)='f' OR lower($1)='false'
OR lower($1)='n' OR lower($1)='no'
THEN
RETURN istrue;
END IF;
{not_bool_exception_str}
Expand Down Expand Up @@ -527,29 +537,35 @@ def get_text_and_datetime_to_datetime_cast_str(type_condition, exception_string)


def _get_timestamp_with_timezone_type_body_map(target_type):
default_behavior_source_types = frozenset([TIMESTAMP_WITH_TIME_ZONE, TIMESTAMP_WITHOUT_TIME_ZONE, DATE]) | TEXT_TYPES
return _get_default_type_body_map(
default_behavior_source_types, target_type,
datetime_source_types = frozenset(
[TIMESTAMP_WITH_TIME_ZONE, TIMESTAMP_WITHOUT_TIME_ZONE, DATE]
)
default_behavior_source_types = datetime_source_types | TEXT_TYPES
return _get_default_type_body_map(default_behavior_source_types, target_type)


def _get_timestamp_without_timezone_type_body_map():
"""
Get SQL strings that create various functions for casting different
types to timestamp without timezone.
We allow casting any text, timezone and date type to be cast into a timestamp without timezone,
provided it does not any timezone information as this could lead to a information loss
We allow casting any text, timezone and date type to be cast into a
timestamp without timezone, provided it does not any timezone
information as this could lead to a information loss

The cast function changes the timezone to `utc` for the transaction is called on.
So this function call should be used in a isolated transaction to avoid timezone change causing unintended side effect
The cast function changes the timezone to `utc` for the transaction
is called on. So this function call should be used in a isolated
transaction to avoid timezone change causing unintended side effect
"""
source_text_types = TEXT_TYPES
source_datetime_types = frozenset([TIMESTAMP_WITH_TIME_ZONE, DATE])
default_behavior_source_types = frozenset([TIMESTAMP_WITHOUT_TIME_ZONE])

not_timestamp_without_tz_exception_str = f"RAISE EXCEPTION '% is not a {TIMESTAMP_WITHOUT_TIME_ZONE}', $1;"
# Check if the value is missing timezone by casting it to a timestamp with timezone
# and comparing if the value is equal to a timestamp without timezone
not_timestamp_without_tz_exception_str = (
f"RAISE EXCEPTION '% is not a {TIMESTAMP_WITHOUT_TIME_ZONE}', $1;"
)
# Check if the value is missing timezone by casting it to a timestamp
# with timezone and comparing if the value is equal to a timestamp
# without timezone.
timestamp_without_tz_condition_str = f"""
IF (timestamp_value_with_tz = timestamp_value) THEN
RETURN $1::{TIMESTAMP_WITHOUT_TIME_ZONE};
Expand All @@ -561,17 +577,19 @@ def _get_timestamp_without_timezone_type_body_map():
)
type_body_map.update(
{
text_type: get_text_and_datetime_to_datetime_cast_str(timestamp_without_tz_condition_str,
not_timestamp_without_tz_exception_str
)
text_type: get_text_and_datetime_to_datetime_cast_str(
timestamp_without_tz_condition_str,
not_timestamp_without_tz_exception_str
)
for text_type in source_text_types
}
)
type_body_map.update(
{
datetime_type: get_text_and_datetime_to_datetime_cast_str(timestamp_without_tz_condition_str,
not_timestamp_without_tz_exception_str
)
datetime_type: get_text_and_datetime_to_datetime_cast_str(
timestamp_without_tz_condition_str,
not_timestamp_without_tz_exception_str
)
for datetime_type in source_datetime_types
}
)
Expand Down Expand Up @@ -624,13 +642,15 @@ def _get_base_textual_cast_to_money():
def _get_textual_type_body_map(engine, target_type_str=VARCHAR):
"""
Get SQL strings that create various functions for casting different
types to varchar.
types to text types through the TEXT type.

All casts to varchar use default PostgreSQL behavior.
All types in get_supported_alter_column_types are supported.
"""
supported_types = get_supported_alter_column_db_types(engine)

# We cast everything through TEXT so that formatting is done correctly
# for CHAR.
text_cast_str = f"""
BEGIN
RETURN $1::{TEXT};
Expand All @@ -644,11 +664,14 @@ def _get_date_type_body_map():
"""
Get SQL strings that create various functions for casting different
types to date.
We allow casting any text, timezone and date type to be cast into a timestamp without timezone,
provided it does not any timezone information as this could lead to a information loss

The cast function changes the timezone to `utc` for the transaction is called on.
So this function call should be used in a isolated transaction to avoid timezone change causing unintended side effect
We allow casting any text, timezone and date type to be cast into a
timestamp without timezone, provided it does not any timezone
information as this could lead to a information loss.

The cast function changes the timezone to `utc` for the transaction
is called on. So this function call should be used in a isolated
transaction to avoid timezone change causing unintended side effect.
"""
# Note that default postgres conversion for dates depends on the
# `DateStyle` option set on the server, which can be one of DMY, MDY,
Expand Down