352 lines
10 KiB
Python
352 lines
10 KiB
Python
from django.db import NotSupportedError
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from django.db.models.expressions import Func, Value
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from django.db.models.fields import CharField, IntegerField
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from django.db.models.functions import Coalesce
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from django.db.models.lookups import Transform
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class MySQLSHA2Mixin:
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def as_mysql(self, compiler, connection, **extra_content):
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return super().as_sql(
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compiler,
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connection,
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template="SHA2(%%(expressions)s, %s)" % self.function[3:],
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**extra_content,
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)
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class OracleHashMixin:
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def as_oracle(self, compiler, connection, **extra_context):
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return super().as_sql(
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compiler,
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connection,
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template=(
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"LOWER(RAWTOHEX(STANDARD_HASH(UTL_I18N.STRING_TO_RAW("
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"%(expressions)s, 'AL32UTF8'), '%(function)s')))"
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),
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**extra_context,
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)
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class PostgreSQLSHAMixin:
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def as_postgresql(self, compiler, connection, **extra_content):
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return super().as_sql(
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compiler,
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connection,
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template="ENCODE(DIGEST(%(expressions)s, '%(function)s'), 'hex')",
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function=self.function.lower(),
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**extra_content,
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)
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class Chr(Transform):
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function = "CHR"
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lookup_name = "chr"
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def as_mysql(self, compiler, connection, **extra_context):
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return super().as_sql(
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compiler,
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connection,
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function="CHAR",
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template="%(function)s(%(expressions)s USING utf16)",
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**extra_context,
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)
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def as_oracle(self, compiler, connection, **extra_context):
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return super().as_sql(
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compiler,
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connection,
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template="%(function)s(%(expressions)s USING NCHAR_CS)",
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**extra_context,
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)
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def as_sqlite(self, compiler, connection, **extra_context):
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return super().as_sql(compiler, connection, function="CHAR", **extra_context)
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class ConcatPair(Func):
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"""
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Concatenate two arguments together. This is used by `Concat` because not
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all backend databases support more than two arguments.
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"""
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function = "CONCAT"
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def as_sqlite(self, compiler, connection, **extra_context):
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coalesced = self.coalesce()
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return super(ConcatPair, coalesced).as_sql(
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compiler,
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connection,
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template="%(expressions)s",
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arg_joiner=" || ",
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**extra_context,
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)
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def as_mysql(self, compiler, connection, **extra_context):
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# Use CONCAT_WS with an empty separator so that NULLs are ignored.
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return super().as_sql(
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compiler,
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connection,
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function="CONCAT_WS",
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template="%(function)s('', %(expressions)s)",
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**extra_context,
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)
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def coalesce(self):
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# null on either side results in null for expression, wrap with coalesce
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c = self.copy()
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c.set_source_expressions(
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[
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Coalesce(expression, Value(""))
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for expression in c.get_source_expressions()
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]
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)
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return c
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class Concat(Func):
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"""
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Concatenate text fields together. Backends that result in an entire
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null expression when any arguments are null will wrap each argument in
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coalesce functions to ensure a non-null result.
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"""
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function = None
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template = "%(expressions)s"
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def __init__(self, *expressions, **extra):
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if len(expressions) < 2:
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raise ValueError("Concat must take at least two expressions")
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paired = self._paired(expressions)
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super().__init__(paired, **extra)
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def _paired(self, expressions):
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# wrap pairs of expressions in successive concat functions
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# exp = [a, b, c, d]
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# -> ConcatPair(a, ConcatPair(b, ConcatPair(c, d))))
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if len(expressions) == 2:
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return ConcatPair(*expressions)
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return ConcatPair(expressions[0], self._paired(expressions[1:]))
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class Left(Func):
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function = "LEFT"
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arity = 2
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output_field = CharField()
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def __init__(self, expression, length, **extra):
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"""
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expression: the name of a field, or an expression returning a string
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length: the number of characters to return from the start of the string
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"""
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if not hasattr(length, "resolve_expression"):
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if length < 1:
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raise ValueError("'length' must be greater than 0.")
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super().__init__(expression, length, **extra)
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def get_substr(self):
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return Substr(self.source_expressions[0], Value(1), self.source_expressions[1])
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def as_oracle(self, compiler, connection, **extra_context):
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return self.get_substr().as_oracle(compiler, connection, **extra_context)
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def as_sqlite(self, compiler, connection, **extra_context):
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return self.get_substr().as_sqlite(compiler, connection, **extra_context)
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class Length(Transform):
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"""Return the number of characters in the expression."""
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function = "LENGTH"
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lookup_name = "length"
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output_field = IntegerField()
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def as_mysql(self, compiler, connection, **extra_context):
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return super().as_sql(
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compiler, connection, function="CHAR_LENGTH", **extra_context
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)
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class Lower(Transform):
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function = "LOWER"
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lookup_name = "lower"
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class LPad(Func):
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function = "LPAD"
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output_field = CharField()
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def __init__(self, expression, length, fill_text=Value(" "), **extra):
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if (
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not hasattr(length, "resolve_expression")
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and length is not None
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and length < 0
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):
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raise ValueError("'length' must be greater or equal to 0.")
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super().__init__(expression, length, fill_text, **extra)
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class LTrim(Transform):
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function = "LTRIM"
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lookup_name = "ltrim"
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class MD5(OracleHashMixin, Transform):
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function = "MD5"
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lookup_name = "md5"
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class Ord(Transform):
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function = "ASCII"
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lookup_name = "ord"
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output_field = IntegerField()
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def as_mysql(self, compiler, connection, **extra_context):
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return super().as_sql(compiler, connection, function="ORD", **extra_context)
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def as_sqlite(self, compiler, connection, **extra_context):
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return super().as_sql(compiler, connection, function="UNICODE", **extra_context)
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class Repeat(Func):
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function = "REPEAT"
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output_field = CharField()
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def __init__(self, expression, number, **extra):
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if (
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not hasattr(number, "resolve_expression")
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and number is not None
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and number < 0
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):
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raise ValueError("'number' must be greater or equal to 0.")
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super().__init__(expression, number, **extra)
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def as_oracle(self, compiler, connection, **extra_context):
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expression, number = self.source_expressions
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length = None if number is None else Length(expression) * number
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rpad = RPad(expression, length, expression)
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return rpad.as_sql(compiler, connection, **extra_context)
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class Replace(Func):
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function = "REPLACE"
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def __init__(self, expression, text, replacement=Value(""), **extra):
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super().__init__(expression, text, replacement, **extra)
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class Reverse(Transform):
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function = "REVERSE"
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lookup_name = "reverse"
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def as_oracle(self, compiler, connection, **extra_context):
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# REVERSE in Oracle is undocumented and doesn't support multi-byte
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# strings. Use a special subquery instead.
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return super().as_sql(
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compiler,
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connection,
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template=(
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"(SELECT LISTAGG(s) WITHIN GROUP (ORDER BY n DESC) FROM "
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"(SELECT LEVEL n, SUBSTR(%(expressions)s, LEVEL, 1) s "
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"FROM DUAL CONNECT BY LEVEL <= LENGTH(%(expressions)s)) "
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"GROUP BY %(expressions)s)"
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),
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**extra_context,
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)
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class Right(Left):
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function = "RIGHT"
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def get_substr(self):
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return Substr(
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self.source_expressions[0], self.source_expressions[1] * Value(-1)
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)
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class RPad(LPad):
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function = "RPAD"
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class RTrim(Transform):
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function = "RTRIM"
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lookup_name = "rtrim"
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class SHA1(OracleHashMixin, PostgreSQLSHAMixin, Transform):
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function = "SHA1"
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lookup_name = "sha1"
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class SHA224(MySQLSHA2Mixin, PostgreSQLSHAMixin, Transform):
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function = "SHA224"
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lookup_name = "sha224"
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def as_oracle(self, compiler, connection, **extra_context):
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raise NotSupportedError("SHA224 is not supported on Oracle.")
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class SHA256(MySQLSHA2Mixin, OracleHashMixin, PostgreSQLSHAMixin, Transform):
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function = "SHA256"
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lookup_name = "sha256"
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class SHA384(MySQLSHA2Mixin, OracleHashMixin, PostgreSQLSHAMixin, Transform):
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function = "SHA384"
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lookup_name = "sha384"
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class SHA512(MySQLSHA2Mixin, OracleHashMixin, PostgreSQLSHAMixin, Transform):
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function = "SHA512"
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lookup_name = "sha512"
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class StrIndex(Func):
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"""
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Return a positive integer corresponding to the 1-indexed position of the
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first occurrence of a substring inside another string, or 0 if the
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substring is not found.
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"""
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function = "INSTR"
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arity = 2
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output_field = IntegerField()
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def as_postgresql(self, compiler, connection, **extra_context):
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return super().as_sql(compiler, connection, function="STRPOS", **extra_context)
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class Substr(Func):
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function = "SUBSTRING"
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output_field = CharField()
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def __init__(self, expression, pos, length=None, **extra):
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"""
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expression: the name of a field, or an expression returning a string
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pos: an integer > 0, or an expression returning an integer
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length: an optional number of characters to return
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"""
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if not hasattr(pos, "resolve_expression"):
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if pos < 1:
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raise ValueError("'pos' must be greater than 0")
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expressions = [expression, pos]
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if length is not None:
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expressions.append(length)
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super().__init__(*expressions, **extra)
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def as_sqlite(self, compiler, connection, **extra_context):
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return super().as_sql(compiler, connection, function="SUBSTR", **extra_context)
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def as_oracle(self, compiler, connection, **extra_context):
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return super().as_sql(compiler, connection, function="SUBSTR", **extra_context)
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class Trim(Transform):
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function = "TRIM"
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lookup_name = "trim"
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class Upper(Transform):
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function = "UPPER"
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lookup_name = "upper"
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