Python sqlalchemy.types 模块，DECIMAL 实例源码

def str_to_sqltype(expr):
    import re
    import sqlalchemy.types as sqltypes
    norm_expr = expr.lower()
    if norm_expr.startswith('integer'):
        match_result = re.match(r'integer\((\d+)\)', norm_expr)
        if match_result is not None:
            return sqltypes.BIGINT() if int(match_result.group(1)) > 11 else sqltypes.INTEGER()
        return sqltypes.BIGINT()
    if norm_expr == 'decimal':
        return sqltypes.DECIMAL()
    if norm_expr == 'date':
        return sqltypes.DATETIME()
    if norm_expr == 'bool' or norm_expr == 'boolean':
        return sqltypes.BOOLEAN()
    if norm_expr.startswith('string'):
        match_result = re.match(r'string\((\d+)\)', norm_expr)
        if match_result is not None:
            maxlen = int(match_result.group(1))
            return sqltypes.VARCHAR(maxlen) if maxlen < 65536 else sqltypes.TEXT
        return sqltypes.TEXT()
    raise RuntimeError("Unsupported data type [" + expr + "]")

def __init__(self, precision=None, scale=None, asdecimal=True, **kw):
        """Construct a DECIMAL.

        :param precision: Total digits in this number.  If scale and precision
          are both None, values are stored to limits allowed by the server.

        :param scale: The number of digits after the decimal point.

        """
        super(DECIMAL, self).__init__(precision=precision, scale=scale,
                                      asdecimal=asdecimal, **kw)

def __init__(self, precision=None, scale=None, asdecimal=True, **kw):
        """Construct a DECIMAL.

        :param precision: Total digits in this number.  If scale and precision
          are both None, values are stored to limits allowed by the server.

        :param scale: The number of digits after the decimal point.

        """
        super(DECIMAL, self).__init__(precision=precision, scale=scale,
                                      asdecimal=asdecimal, **kw)

def __init__(self, precision=None, scale=None, asdecimal=True, **kw):
        """Construct a DECIMAL.

        :param precision: Total digits in this number.  If scale and precision
          are both None, values are stored to limits allowed by the server.

        :param scale: The number of digits after the decimal point.

        """
        super(DECIMAL, self).__init__(precision=precision, scale=scale,
                                      asdecimal=asdecimal, **kw)

def sqltype_to_stdtype(sqltype):
    import sqlalchemy.types as sqltypes
    if isinstance(sqltype, (sqltypes.VARCHAR, sqltypes.CHAR, sqltypes.TEXT, sqltypes.Enum, sqltypes.String)):
        return _STRING_TYPE
    if isinstance(sqltype, (sqltypes.DATETIME, sqltypes.DATE, sqltypes.TIME, sqltypes.TIMESTAMP)):
        return _DATE_TYPE
    if isinstance(sqltype, (sqltypes.INTEGER, sqltypes.BIGINT, sqltypes.SMALLINT, sqltypes.Integer)):
        return _INTEGER_TYPE
    if isinstance(sqltype, (sqltypes.REAL, sqltypes.DECIMAL, sqltypes.NUMERIC, sqltypes.FLOAT)):
        return _DECIMAL_TYPE
    if isinstance(sqltype, sqltypes.BOOLEAN):
        return _BOOLEAN_TYPE

def stdtype_to_sqltype(stdtype):
    import sqlalchemy.types as sqltypes
    if isinstance(stdtype, stdtypes.StringType):
        return sqltypes.VARCHAR(length=stdtype.max_len) if 0 < stdtype.max_len < 65536 else sqltypes.TEXT()
    if isinstance(stdtype, stdtypes.BoolType):
        return sqltypes.BOOLEAN()
    if isinstance(stdtype, stdtypes.DateType):
        return sqltypes.DATE() if stdtype.only_date else sqltypes.TIMESTAMP()
    if isinstance(stdtype, stdtypes.IntegerType):
        return sqltypes.BIGINT() if stdtype.length > 11 else sqltypes.INTEGER()
    if isinstance(stdtype, stdtypes.DecimalType):
        return sqltypes.DECIMAL()
    if isinstance(stdtype, stdtypes.ArrayType):
        return sqltypes.ARRAY(item_type=stdtype.item_type)

def load_dialect_impl(self, dialect):
        if dialect.name == 'mysql':
            return dialect.type_descriptor(
                types.DECIMAL(precision=20,
                              scale=6,
                              asdecimal=True))
        return dialect.type_descriptor(self.impl)

def compare_against_backend(self, dialect, conn_type):
        if dialect.name == 'mysql':
            return issubclass(type(conn_type), types.DECIMAL)
        return issubclass(type(conn_type), type(self.impl))