221 lines
8.3 KiB
Python
221 lines
8.3 KiB
Python
"""Database functions that do comparisons or type conversions."""
|
|
from django.db import NotSupportedError
|
|
from django.db.models.expressions import Func, Value
|
|
from django.db.models.fields import TextField
|
|
from django.db.models.fields.json import JSONField
|
|
from django.utils.regex_helper import _lazy_re_compile
|
|
|
|
|
|
class Cast(Func):
|
|
"""Coerce an expression to a new field type."""
|
|
|
|
function = "CAST"
|
|
template = "%(function)s(%(expressions)s AS %(db_type)s)"
|
|
|
|
def __init__(self, expression, output_field):
|
|
super().__init__(expression, output_field=output_field)
|
|
|
|
def as_sql(self, compiler, connection, **extra_context):
|
|
extra_context["db_type"] = self.output_field.cast_db_type(connection)
|
|
return super().as_sql(compiler, connection, **extra_context)
|
|
|
|
def as_sqlite(self, compiler, connection, **extra_context):
|
|
db_type = self.output_field.db_type(connection)
|
|
if db_type in {"datetime", "time"}:
|
|
# Use strftime as datetime/time don't keep fractional seconds.
|
|
template = "strftime(%%s, %(expressions)s)"
|
|
sql, params = super().as_sql(
|
|
compiler, connection, template=template, **extra_context
|
|
)
|
|
format_string = "%H:%M:%f" if db_type == "time" else "%Y-%m-%d %H:%M:%f"
|
|
params.insert(0, format_string)
|
|
return sql, params
|
|
elif db_type == "date":
|
|
template = "date(%(expressions)s)"
|
|
return super().as_sql(
|
|
compiler, connection, template=template, **extra_context
|
|
)
|
|
return self.as_sql(compiler, connection, **extra_context)
|
|
|
|
def as_mysql(self, compiler, connection, **extra_context):
|
|
template = None
|
|
output_type = self.output_field.get_internal_type()
|
|
# MySQL doesn't support explicit cast to float.
|
|
if output_type == "FloatField":
|
|
template = "(%(expressions)s + 0.0)"
|
|
# MariaDB doesn't support explicit cast to JSON.
|
|
elif output_type == "JSONField" and connection.mysql_is_mariadb:
|
|
template = "JSON_EXTRACT(%(expressions)s, '$')"
|
|
return self.as_sql(compiler, connection, template=template, **extra_context)
|
|
|
|
def as_postgresql(self, compiler, connection, **extra_context):
|
|
# CAST would be valid too, but the :: shortcut syntax is more readable.
|
|
# 'expressions' is wrapped in parentheses in case it's a complex
|
|
# expression.
|
|
return self.as_sql(
|
|
compiler,
|
|
connection,
|
|
template="(%(expressions)s)::%(db_type)s",
|
|
**extra_context,
|
|
)
|
|
|
|
def as_oracle(self, compiler, connection, **extra_context):
|
|
if self.output_field.get_internal_type() == "JSONField":
|
|
# Oracle doesn't support explicit cast to JSON.
|
|
template = "JSON_QUERY(%(expressions)s, '$')"
|
|
return super().as_sql(
|
|
compiler, connection, template=template, **extra_context
|
|
)
|
|
return self.as_sql(compiler, connection, **extra_context)
|
|
|
|
|
|
class Coalesce(Func):
|
|
"""Return, from left to right, the first non-null expression."""
|
|
|
|
function = "COALESCE"
|
|
|
|
def __init__(self, *expressions, **extra):
|
|
if len(expressions) < 2:
|
|
raise ValueError("Coalesce must take at least two expressions")
|
|
super().__init__(*expressions, **extra)
|
|
|
|
@property
|
|
def empty_result_set_value(self):
|
|
for expression in self.get_source_expressions():
|
|
result = expression.empty_result_set_value
|
|
if result is NotImplemented or result is not None:
|
|
return result
|
|
return None
|
|
|
|
def as_oracle(self, compiler, connection, **extra_context):
|
|
# Oracle prohibits mixing TextField (NCLOB) and CharField (NVARCHAR2),
|
|
# so convert all fields to NCLOB when that type is expected.
|
|
if self.output_field.get_internal_type() == "TextField":
|
|
clone = self.copy()
|
|
clone.set_source_expressions(
|
|
[
|
|
Func(expression, function="TO_NCLOB")
|
|
for expression in self.get_source_expressions()
|
|
]
|
|
)
|
|
return super(Coalesce, clone).as_sql(compiler, connection, **extra_context)
|
|
return self.as_sql(compiler, connection, **extra_context)
|
|
|
|
|
|
class Collate(Func):
|
|
function = "COLLATE"
|
|
template = "%(expressions)s %(function)s %(collation)s"
|
|
# Inspired from
|
|
# https://www.postgresql.org/docs/current/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS
|
|
collation_re = _lazy_re_compile(r"^[\w\-]+$")
|
|
|
|
def __init__(self, expression, collation):
|
|
if not (collation and self.collation_re.match(collation)):
|
|
raise ValueError("Invalid collation name: %r." % collation)
|
|
self.collation = collation
|
|
super().__init__(expression)
|
|
|
|
def as_sql(self, compiler, connection, **extra_context):
|
|
extra_context.setdefault("collation", connection.ops.quote_name(self.collation))
|
|
return super().as_sql(compiler, connection, **extra_context)
|
|
|
|
|
|
class Greatest(Func):
|
|
"""
|
|
Return the maximum expression.
|
|
|
|
If any expression is null the return value is database-specific:
|
|
On PostgreSQL, the maximum not-null expression is returned.
|
|
On MySQL, Oracle, and SQLite, if any expression is null, null is returned.
|
|
"""
|
|
|
|
function = "GREATEST"
|
|
|
|
def __init__(self, *expressions, **extra):
|
|
if len(expressions) < 2:
|
|
raise ValueError("Greatest must take at least two expressions")
|
|
super().__init__(*expressions, **extra)
|
|
|
|
def as_sqlite(self, compiler, connection, **extra_context):
|
|
"""Use the MAX function on SQLite."""
|
|
return super().as_sqlite(compiler, connection, function="MAX", **extra_context)
|
|
|
|
|
|
class JSONObject(Func):
|
|
function = "JSON_OBJECT"
|
|
output_field = JSONField()
|
|
|
|
def __init__(self, **fields):
|
|
expressions = []
|
|
for key, value in fields.items():
|
|
expressions.extend((Value(key), value))
|
|
super().__init__(*expressions)
|
|
|
|
def as_sql(self, compiler, connection, **extra_context):
|
|
if not connection.features.has_json_object_function:
|
|
raise NotSupportedError(
|
|
"JSONObject() is not supported on this database backend."
|
|
)
|
|
return super().as_sql(compiler, connection, **extra_context)
|
|
|
|
def as_postgresql(self, compiler, connection, **extra_context):
|
|
copy = self.copy()
|
|
copy.set_source_expressions(
|
|
[
|
|
Cast(expression, TextField()) if index % 2 == 0 else expression
|
|
for index, expression in enumerate(copy.get_source_expressions())
|
|
]
|
|
)
|
|
return super(JSONObject, copy).as_sql(
|
|
compiler,
|
|
connection,
|
|
function="JSONB_BUILD_OBJECT",
|
|
**extra_context,
|
|
)
|
|
|
|
def as_oracle(self, compiler, connection, **extra_context):
|
|
class ArgJoiner:
|
|
def join(self, args):
|
|
args = [" VALUE ".join(arg) for arg in zip(args[::2], args[1::2])]
|
|
return ", ".join(args)
|
|
|
|
return self.as_sql(
|
|
compiler,
|
|
connection,
|
|
arg_joiner=ArgJoiner(),
|
|
template="%(function)s(%(expressions)s RETURNING CLOB)",
|
|
**extra_context,
|
|
)
|
|
|
|
|
|
class Least(Func):
|
|
"""
|
|
Return the minimum expression.
|
|
|
|
If any expression is null the return value is database-specific:
|
|
On PostgreSQL, return the minimum not-null expression.
|
|
On MySQL, Oracle, and SQLite, if any expression is null, return null.
|
|
"""
|
|
|
|
function = "LEAST"
|
|
|
|
def __init__(self, *expressions, **extra):
|
|
if len(expressions) < 2:
|
|
raise ValueError("Least must take at least two expressions")
|
|
super().__init__(*expressions, **extra)
|
|
|
|
def as_sqlite(self, compiler, connection, **extra_context):
|
|
"""Use the MIN function on SQLite."""
|
|
return super().as_sqlite(compiler, connection, function="MIN", **extra_context)
|
|
|
|
|
|
class NullIf(Func):
|
|
function = "NULLIF"
|
|
arity = 2
|
|
|
|
def as_oracle(self, compiler, connection, **extra_context):
|
|
expression1 = self.get_source_expressions()[0]
|
|
if isinstance(expression1, Value) and expression1.value is None:
|
|
raise ValueError("Oracle does not allow Value(None) for expression1.")
|
|
return super().as_sql(compiler, connection, **extra_context)
|