选项1

Question

我有以下代码，当我在return redirect(url_for)和present函数上尝试future时，收到以下错误消息：

TypeError：home（）缺少1个必需的位置参数：“ calc_type”

我尝试了多种方法将calc_type变量传递给home函数，并始终得到相同的错误。任何帮助表示赞赏。

from flask import render_template, redirect, url_for, request
from app import app, db
from models import Pres, Future

@app.route('/home')
def home(calc_type):
    if (calc_type == "present"):
        try:
            inputs = Pres.query.all()
            for item in inputs:
                cash = item.cash
                rate = item.rate
                periods = item.periods
            pv = cash / (1 + rate)**periods
            return render_template('present.html', inputs=inputs, cash=cash, pv=pv)
        except:
            return render_template('present.html')
    elif (calc_type == "future"):
        inputs = Future.query.all()
        for item in inputs:
            cash = item.cash
            rate = item.rate
            periods = item.periods
        fv = cash * (1 + rate)**periods
        return render_template('present.html', inputs=inputs, cash=cash, fv=fv)

@app.route('/present', methods=['GET', 'POST'])
def present():
    input = Pres(request.form['cash'], request.form['rate'], request.form['periods'])
    calc_type = "present"
    db.session.add(input)
    db.session.commit()
    return redirect(url_for('home', calc_type=calc_type))

@app.route('/future', methods=['GET', 'POST'])
def future():
    input = Future(request.form['cash'], request.form['rate'], request.form['periods'])
    calc_type = "future"
    db.session.add(input)
    db.session.commit()
    return redirect(url_for('home', calc_type=calc_type))

Answer 1

您以ListBox视图的方式，无法从home()接收参数，因为路由路径中没有这样的变量。

View函数由flask包装，并且其行为与常规函数不同。要使主视图接收该变量，您必须在其路径路径中定义一个变量：

url_to

或者，您可以将其作为url查询变量传递：

@app.route('/home/<string:calc_type>')
def home(calc_type):
   ...

# Result:
>>> url_for('route', calc_type='present')
'/home/present'

但是最重要的是，您还应该尝试将视图/路由逻辑与其他代码分开，并使视图尽可能地简洁。

有两种方法可以解决此问题：

选项1

PS：我不会这样做，但它与您的代码最接近。

@app.route('/home')
def home():
   calc_type = request.args.get('calc_type')

# Result:
>>> url_for('route', calc_type='present')
'/home?calc_type=present'

选项2

def get_view(calc_type):
    if (calc_type == "present"):
        try:
            inputs = Pres.query.all()
            for item in inputs:
                cash = item.cash
                rate = item.rate
                periods = item.periods
            pv = cash / (1 + rate)**periods
            return render_template('present.html', inputs=inputs, cash=cash, pv=pv)
        except:
            return render_template('present.html')
    elif (calc_type == "future"):
        inputs = Future.query.all()
        for item in inputs:
            cash = item.cash
            rate = item.rate
            periods = item.periods
        fv = cash * (1 + rate)**periods
        return render_template('present.html', inputs=inputs, cash=cash, fv=fv)


@app.route('/present', methods=['GET', 'POST'])
def present():
    input = Pres(request.form['cash'], request.form['rate'], request.form['periods'])
    calc_type = "present"
    db.session.add(input)
    db.session.commit()
    return get_view(calc_type)

@app.route('/future', methods=['GET', 'POST'])
def future():
    input = Future(request.form['cash'], request.form['rate'], request.form['periods'])
    calc_type = "future"
    db.session.add(input)
    db.session.commit()
    return get_view(calc_type)

缺少参数的烧瓶返回重定向（url_for）错误

1 个答案:

选项1

选项2