返回 SQLAlchemy 查询结果时出现 Python Flask 类型错误

问题描述

我运行查询以在网络表单上填充 a。正在工作。我单击提交，这应该将选择发布回 Flask，后者在其上运行查询。我收到 TypeError：BaseQuery 类型的对象不是 JSON 可序列化的。

这部分似乎工作正常，直到我点击“提交”：

<form RoomSelectForm action = "#" method = "post">
        <p><label>Select Room</label>
        <select name="roomselect">
            {% for room in roomselect %}
                <option value="{{ room[0] }}">{{ room[0] }}</option>
            {% endfor %}
        </select>
    <input type ="submit" value ="Edit Room" onclick="toggleform()"></p>
</form>

我认为这个 sqlAlchemy 查询出现了问题：

@app.route("/editroom",methods=["POST"])
def edit_room_original_values():
    rm = request.form['roomselect']
    rmval = Roomtable.query.filter(Roomtable.room == rm)
    return dict(value=rmval)

这是错误：

TypeError
TypeError: Object of type BaseQuery is not JSON serializable

Traceback (most recent call last)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\app.py",line 2464,in __call__
return self.wsgi_app(environ,start_response)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\app.py",line 2450,in wsgi_app
response = self.handle_exception(e)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\app.py",line 1867,in handle_exception
reraise(exc_type,exc_value,tb)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\_compat.py",line 39,in reraise
raise value
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\app.py",line 2447,in wsgi_app
response = self.full_dispatch_request()
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\app.py",line 1953,in full_dispatch_request
return self.finalize_request(rv)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\app.py",line 1968,in finalize_request
response = self.make_response(rv)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\app.py",line 2112,in make_response
rv = jsonify(rv)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\json\__init__.py",line 370,in jsonify
dumps(data,indent=indent,separators=separators) + "\n",File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\json\__init__.py",line 211,in dumps
rv = _json.dumps(obj,**kwargs)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\json\__init__.py",line 234,in dumps
return cls(
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\json\encoder.py",line 201,in encode
chunks = list(chunks)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\json\encoder.py",line 431,in _iterencode
yield from _iterencode_dict(o,_current_indent_level)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\json\encoder.py",line 405,in _iterencode_dict
yield from chunks
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\json\encoder.py",line 438,in _iterencode
o = _default(o)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\site-packages\flask\json\__init__.py",line 100,in default
return _json.JSONEncoder.default(self,o)
File "C:\Users\user1\AppData\Local\Programs\Python\python38\Lib\json\encoder.py",line 179,in default
raise TypeError(f'Object of type {o.__class__.__name__} '
TypeError: Object of type BaseQuery is not JSON serializable
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解决方法

rmval = Roomtable.query.filter(Roomtable.room == rm)

在这一行中，Roomtable.query.filter() 返回一个 BaseQuery 对象。您可能希望使用 first()（然后返回一个 Roomtable 对象）来获取第一个查询结果。

试试这个

rmval = Roomtable.query.filter(Roomtable.room == rm).first()

查询是一个需要传入一个类的方法，以便它知道返回过滤结果为：

rmval = Roomtable.query(Room).filter(Roomtable.room == rm)

假设 Room 作为一个类。

flask jsonify python sqlalchemy