使用 Flask POST 后，选择选项保持选中状态

Question

我正在尝试获取一个选择选项，该选项在使用 Flask 刷新页面后被选中。我曾尝试使用 Jinga2 这样做，但它不起作用：

<div class="col-sm-4 col-lg-4 col-md-4">
    <select class="form-control" id="myselect" name="thing" required>
        <option value="" {% if thing=='' %} selected {% endif %} ></option>
        <option value="Foo" name="Foo" id="Foo" {% if thing =="Foo" %} selected {% endif %}>Foo</option>
        <option value="Bar" name="Bar" id="Bar" {% if thing =="Bar" %} selected {% endif %}>Bar</option>
    </select>
</div>

energy使用 Python 填充和传递变量的位置。在研究了这个之后，我觉得这是在 Flask 中进行这项工作的方式，尽管显然不是。任何援助将不胜感激！

@app,route('/things', methods=['POST']
def things()
    if len(facts['thing']) > 11:
        energy = [facts['thing'][0:8],facts['thing'][9:]]
    else:
        energy = [facts['things']]
    ...
    return render_template('thing.html', thing=energy)

Answer 1

请参阅此示例，因为它适用于您正在尝试执行的操作。我无法完全调试您的代码中出了什么问题，因为您为我提供了零件，而我不知道他们在做什么。

文件夹结构

Test
|___templates
|   |___things.html
|___Test.py

东西.html

<form method="post">
    <div class="col-sm-4 col-lg-4 col-md-4">
        <select title="thing" class="form-control" id="myselect" name="thing" required>
            <option value="" {% if thing=='' %} selected {% endif %} ></option>
            <option value="Foo" name="Foo" id="Foo" {% if thing =="Foo" %} selected {% endif %} >Foo</option>
            <option value="Bar" name="Bar" id="Bar" {% if thing =='Bar' %} selected {% endif %}>Bar</option>
        </select>
        <button type="submit">SEND</button>
    </div>
</form>

测试文件

from flask import Flask, render_template, request

app = Flask(__name__)
PORT = 5000


@app.route('/things', methods=['GET', 'POST'])
def things():
    """
    Accepts both GET and POST requests. If it's a GET request,
    you wouldn't have a last selected thing, so it's set to an
    empty string. If it's a POST request, we fetch the selected
    thing and return the same template with the pre-selected
    thing.
    You can improve on this and save the last selected thing
    into the session data and attempt to retrieve it from there.
    """
    thing = ''
    if request.method == 'GET':
        return render_template('things.html', thing=thing)
    else:
        thing = request.form.get('thing', '')
        return render_template('things.html', thing=thing)


if __name__ == '__main__':
    app.run(port=PORT)