json构造sql查询.py

# 基于 peewee，需要传入 model 类和查询条件


def parse_query(sheet_model, statements):
    """
    statements:
    ['and',
        ['==', 'col1', val1],
        ['!=', 'col2', val2],
        ['and',
            ['==', 'col3', val3],
            ['!=', 'col4', val4],
        ]
    ]
    """
    query = sheet_model.select()

    bin_op = {
        '==': '__eq__',
        '!=': '__ne__',
    }

    logic_op = {
        'and': '__and__',
        #'or': '__or__',
    }

    def parse_binary_op(q, s):
        if s[0] in bin_op:
            col = getattr(sheet_model, s[1])
            return q.where(getattr(col, bin_op[s[0]])(s[2]))
        else:
            raise SyntaxError('查询格式异常：未识别的二元算符 %r' % s[0])

    def parse_logic_op(q, s):
        if s[0] in logic_op:
            for i in s[1:]:
                q = parse_binary_op(q, i)
            return q
        raise SyntaxError('查询格式异常：未识别的逻辑符 %r' % s[0])

    def parse_stmt(q, s):
        if len(s) == 0:
            return q
        if type(s[0]) == list:
            for i in s:
                q = parse_binary_op(q, i)
            return q
        else:
            return parse_logic_op(q, s)

    # 这里注意一点，where里能写表达式的真相，其实是对column的运算符重载，而不是通过反射获取了参数的表达式
    return parse_stmt(query, statements)