Question

I'm very new to Python and Flask and I can't figure out why I don't have the list of data available to me here (ranked_list is empty).

If I comment out all the Flask parts and just call getDataFromQuery to get the data like a normal script, I can see the data and print it out. Can anyone see what I'm doing wrong? The data is a list of tuples. The index.html page is below the code and it is in the templates folder. All I get is a blank table with the header row.

from flask import Flask
from flask import render_template
from flask import request
from queryProcessing_and_Ranking import *

app = Flask(__name__)

@app.route("/")
@app.route("/<query>")
def index():
    query = request.args.get("query")

    Processing = QueryProcessing()
    ranked_list = Processing.getDataFromQuery( query )
    return render_template( "index.html", ranked_list = ranked_list, user_input = query )

if __name__ == '__main__':
    port = int( os.environ.get('PORT', 5000 ) )
app.run( host='0.0.0.0', port=port, debug=True)

<html>
    <head>
        <title>Product Vertical Search Engine</title>
    <link rel="stylesheet" type="text/css" href="{{ url_for('static', filename='style.css') }}">
    </head>
    <body>
        <form>
            Product Search: <input type="text" name="query"> <input type="Submit" value="Search">
        </form>
        <h1>Ranked product listing for: {{user_input}}</h1>
        <table border = "1">
            <tr>
                <th>Title</th><th>Price</th>
            </tr>
            {% for item in ranked_list %}
                <tr>
                    <td>{{item[0]}}</td>
                </tr>
            {% endfor %}
        </table>
    </body>
</html>

Answer 1

鉴于您的路线设置query很可能None，因此您将None传递给.getDataFromQuery方法。

@app.route('/')
def index():

    '''
    Returns "None" if not found.
    So when you open your browser to localhost:5000
    this value is None
    unless you visit localhost:5000/something
    then query = "something"
    '''
    query = request.args.get('query') 
    Processing = QueryProcessing()

    ranked_list = Processing.getDataFromQuery(query) # Value could be None
    return render_template( "index.html", ranked_list = ranked_list, user_input = query )

您还应删除捕获<query>的路线定义，因为您似乎正在混淆path parameters和query string parameters的概念

修改

这看起来像你要做的是搜索表单提交，所以我会做以下

@app.route('/') def index(): user_input = None ranked_list = None if request.method == 'POST': user_input = request.form['query'] Processing = QueryProcessing() ranked_list = Processing.getDataFromQuery(user_input) return render_template("index.html", ranked_list=ranked_list, user_input=user_input)

HTML文件

<html> <head> <title>Product Vertical Search Engine</title> <link rel="stylesheet" type="text/css" href="{{ url_for('static', filename='style.css') }}"> </head> <body> <form> Product Search: <input type="text" name="query"> <input type="Submit" value="Search"> </form> {% if user_input %}  <h1>Ranked product listing for: {{user_input}}</h1> <table border = "1"> <tr> <th>Title</th><th>Price</th> </tr> {% for item in ranked_list %} <tr> <td>{{item[0]}}</td> </tr> {% endfor %} </table> {% else %}  <h1>Search for data</h1> {% endif %} </body> </html>

使用一些Jinja2逻辑明确声明没有任何东西可以提供更好的反馈

List generated from class is not available returning render_template in flask

1 个答案: