Исходный код django.db.models.functions.text

from django.db import NotSupportedError
from django.db.models.expressions import Func, Value
from django.db.models.fields import CharField, IntegerField
from django.db.models.functions import Coalesce
from django.db.models.lookups import Transform


class MySQLSHA2Mixin:
    def as_mysql(self, compiler, connection, **extra_content):
        return super().as_sql(
            compiler,
            connection,
            template='SHA2(%%(expressions)s, %s)' % self.function[3:],
            **extra_content,
        )


class OracleHashMixin:
    def as_oracle(self, compiler, connection, **extra_context):
        return super().as_sql(
            compiler,
            connection,
            template=(
                "LOWER(RAWTOHEX(STANDARD_HASH(UTL_I18N.STRING_TO_RAW("
                "%(expressions)s, 'AL32UTF8'), '%(function)s')))"
            ),
            **extra_context,
        )


class PostgreSQLSHAMixin:
    def as_postgresql(self, compiler, connection, **extra_content):
        return super().as_sql(
            compiler,
            connection,
            template="ENCODE(DIGEST(%(expressions)s, '%(function)s'), 'hex')",
            function=self.function.lower(),
            **extra_content,
        )


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