如何使用 Flask 为 Pandas 数据框设置“下载为 csv”按钮？

Question

我试图为我的熊猫数据框（作为 csv）设置一个下载按钮，但我没有取得任何成功。

下面是我的views.py的相关功能：

from flask import render_template, make_response
from flask import send_file
import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
import random
import seaborn as sns




@app.route("/jinja")
def jinja():

    my_name = "Testes"

    return render_template("/public/jinja.html", my_name=my_name)

@app.route("/about")
def about():
    return render_template("/public/about.html")

#defining parameters
bast_param = [0,5] #ba prefix for below average student
avst_param = [5,7] #av prefix for average student
aast_param = [7,10] #aa prefix for above average student

min_bast = bast_param[0]
max_bast = bast_param[1]
min_avst = avst_param[0]
max_avst = avst_param[1]
min_aast = aast_param[0]
max_aast = aast_param[1]


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


    #students quantities per parameter
    bast_qtd = 5
    avst_qtd = 3
    aast_qtd = 8
    st_total = bast_qtd + avst_qtd + aast_qtd

    #Defining Subjects
    subjects = ["Disciplina 1", "Disciplina 2", "Disciplina 3", "Disciplina 4", "Disciplina 5"]

    students = []

    #counter for students ids creation
    i = 0

    #counters and variable for grades creation
    a = 0
    b = 0
    newgradeline = []

    grade = []

    #creating students and grades
    while(i < st_total):
        newstudent = random.randint(100000,199999)
        #excluding duplicates
        if newstudent not in students:
            students.append(newstudent)
            i = i+1


    # In[3]:


    #below averagge students
    while (a < bast_qtd):
        b = 0
        newgradeline = []
        grade.append(newgradeline)
        while (b<len(subjects)):
            gen_grade = round(random.uniform(bast_param[0],bast_param[1]),2)
            newgradeline.append(gen_grade)
            b = b+1
        a = a +1
    a = 0

    #average students
    while (a < avst_qtd):
        b = 0
        newgradeline = []
        grade.append(newgradeline)
        while (b<len(subjects)):
            gen_grade = round(random.uniform(avst_param[0],avst_param[1]),2)
            newgradeline.append(gen_grade)
            b = b+1
        a = a +1
    a = 0

    #above average students
    while (a < aast_qtd):
        b = 0
        newgradeline = []
        grade.append(newgradeline)
        while (b<len(subjects)):
            gen_grade = round(random.uniform(aast_param[0],aast_param[1]),2)
            newgradeline.append(gen_grade)
            b = b+1
        a = a +1


    # In[4]:


    #generating table
    simulation = pd.DataFrame (grade,index=students, columns=subjects)
    return render_template('/public/index.html',table=simulation.to_html(),download_csv=simulation.to_csv(index=True, sep=";"))


@app.route("/parameters")
def parameters():
    return render_template('/public/parameters.html', min_bast=min_bast, max_bast=max_bast, min_avst=min_avst,max_avst=max_avst, min_aast=min_aast, max_aast=max_aast)

这是 html 页面，我目前将 csv 作为文本显示在页面{{download_csv | safe}} {{download_csv | safe}} ：

{% extends "/public/templates/public_template.html" %}

{% block  title %}Simulador{% endblock%}

{% block main %}
  <div class="container">
    <div class="row">
      <div class="col">
      </br>
        <h1>Simulador</h1>
      <hr/>
        {{table| safe}}
        <br />
      <a class="btn btn-primary" href="/" role="button">New simulation</a>
      <a class="btn btn-primary" href="/parameters" role="button">Edit Parameters</a>
      </div>
    </div>
    <div class="row">
      <div class="col">
      </br>
      <hr/>
        <h1>CSV File</h1>
        {{download_csv | safe}}
      </br></br>
        <a class="btn btn-primary" href="" role="button">Download CSV</a>
        <hr/>
    </div>
    </div>
  </div>

{% endblock %}

但我想要这个按钮<a class="btn btn-primary" href="" role="button">Download CSV</a>触发在@app.route("/") def index():我的views.py

我知道我需要在我的 views.py 上设置一条新路线才能进行此下载，但我该怎么做？

Answer 1

目前您的按钮下载没有做任何事情。

1 - OnClick=someFunction()添加OnClick=someFunction()以便当用户单击它时， someFunction()被执行。

<a class="btn btn-primary" onClick="someFunction()" href="" role="button">Download CSV</a>

2 - 在您的somFunction()将网页重定向到您想要的路线，例如location.replace("/download");

function someFunction()
{
    //..... You can here send user input from HTML to Flask through Ajax POST request if you wish.........//
    location.replace("/download");

}

3 - 最后，在你的 Flask 中，确保你有一个/download路径来处理 csv。

更新如果您不想使用 javascript 函数进行重定向，请尝试以下操作：

1 - 将您的 index() 路由更改为更明显的内容，例如@app.route("/download")

2 - 将下载 CSV 按钮的 href 分配给函数的路由

<a class="btn btn-primary" href="{{ url_for('index') }}" role="button">Download CSV</a>

Answer 2

我要做的是将模拟的创建移动到单独的函数 create_simulation() 并为下载创建一个新路由，如下所示：

from flask import render_template, make_response, Response
from flask import send_file
import numpy as np
import matplotlib.pyplot as plt
import pandas as pd
import random
import seaborn as sns




@app.route("/jinja")
def jinja():

    my_name = "Testes"

    return render_template("/public/jinja.html", my_name=my_name)

@app.route("/about")
def about():
    return render_template("/public/about.html")

#defining parameters
bast_param = [0,5] #ba prefix for below average student
avst_param = [5,7] #av prefix for average student
aast_param = [7,10] #aa prefix for above average student

min_bast = bast_param[0]
max_bast = bast_param[1]
min_avst = avst_param[0]
max_avst = avst_param[1]
min_aast = aast_param[0]
max_aast = aast_param[1]


@app.route("/")
def index():
    simulation = create_simulation()
    return render_template('/public/index.html',table=simulation.to_html(),download_csv=simulation.to_csv(index=True, sep=";"))


@app.route('/download')
def download():
    # stream the response as the data is generated
    response = Response(create_simulation(), mimetype='text/csv')
    # add a filename
    response.headers.set("Content-Disposition", "attachment", filename="simulation.csv")
    return response


@app.route("/parameters")
def parameters():

    return render_template('/public/parameters.html', min_bast=min_bast, max_bast=max_bast, min_avst=min_avst,max_avst=max_avst, min_aast=min_aast, max_aast=max_aast)


def create_simulation():

    #students quantities per parameter
    bast_qtd = 5
    avst_qtd = 3
    aast_qtd = 8
    st_total = bast_qtd + avst_qtd + aast_qtd

    #Defining Subjects
    subjects = ["Disciplina 1", "Disciplina 2", "Disciplina 3", "Disciplina 4", "Disciplina 5"]

    students = []

    #counter for students ids creation
    i = 0

    #counters and variable for grades creation
    a = 0
    b = 0
    newgradeline = []

    grade = []

    #creating students and grades
    while(i < st_total):
        newstudent = random.randint(100000,199999)
        #excluding duplicates
        if newstudent not in students:
            students.append(newstudent)
            i = i+1


    # In[3]:


    #below averagge students
    while (a < bast_qtd):
        b = 0
        newgradeline = []
        grade.append(newgradeline)
        while (b<len(subjects)):
            gen_grade = round(random.uniform(bast_param[0],bast_param[1]),2)
            newgradeline.append(gen_grade)
            b = b+1
        a = a +1
    a = 0

    #average students
    while (a < avst_qtd):
        b = 0
        newgradeline = []
        grade.append(newgradeline)
        while (b<len(subjects)):
            gen_grade = round(random.uniform(avst_param[0],avst_param[1]),2)
            newgradeline.append(gen_grade)
            b = b+1
        a = a +1
    a = 0

    #above average students
    while (a < aast_qtd):
        b = 0
        newgradeline = []
        grade.append(newgradeline)
        while (b<len(subjects)):
            gen_grade = round(random.uniform(aast_param[0],aast_param[1]),2)
            newgradeline.append(gen_grade)
            b = b+1
        a = a +1


    # In[4]:
    #generating table
    simulation = pd.DataFrame (grade,index=students, columns=subjects)
    return simulation

然后你的 html 应该看起来像这样，我只将 href 更改为“/下载”：

{% extends "/public/templates/public_template.html" %}

{% block  title %}Simulador{% endblock%}

{% block main %}
  <div class="container">
    <div class="row">
      <div class="col">
      </br>
        <h1>Simulador</h1>
      <hr/>
        {{table| safe}}
        <br />
      <a class="btn btn-primary" href="/" role="button">New simulation</a>
      <a class="btn btn-primary" href="/parameters" role="button">Edit Parameters</a>
      </div>
    </div>
    <div class="row">
      <div class="col">
      </br>
      <hr/>
        <h1>CSV File</h1>
        {{download_csv | safe}}
      </br></br>
        <a class="btn btn-primary" href="/download" role="button">Download CSV</a>
        <hr/>
    </div>
    </div>
  </div>

{% endblock %}

我基本上遵循了这个例子： Create and download a CSV file from a Flask view