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Create for and if loop for inputs in flask

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by vsasikalabe dot icon Updated: Mar 2, 2023

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We can run a loop in the HTML code using the jinja template through Flask. HTML code can be generated using this template. Using Flask, the code will be stored in Directories. The HTTP protocol method is defined as a Flask POST request. It enables users to send HTML form data to the server. The locals() function returns the local symbol table. This table contains necessary information about the current program. 


We will be making two directories for storing the Flask Code: 

  • static – This is for Files like images, CSS, js 
  • templates – For Html templates 

Implementing the code requires two files – A python file and an HTML file.  

  • Python code: a list is made, which we will run in the for loop of the HTML file.  
  • The HTML code: It simply requires a for loop per the jinja template. 

Run the Python file on the terminal or command prompt to execute the code. In the HTML page, the if condition is to get data and conditions depending on routes.py data. Some elements of the page are to be visible. And does not depend on boolean variables stored in the routes.py file. The keywords are if, else, and endif. After the if-condition colon symbol is part of the syntax. In Python, Itertools is a module. It is used to provide various functions over data structures using a for-loop. These types of data structures are also known as iterables. This module works as a fast and memory-efficient tool. It is used either by itself or in combination to form iterator algebra. 


Here is an example of how to create for and if the loop for inputs in Flask: 

Preview of the output that you will get on running this code from your IDE.

Code

In this solution we used flask and jinja library of python.

How to create for and if loop for inputs in jinja flask

PythondotLines of Code : 67dotLicense : Strong Copyleft (CC BY-SA 4.0)

Dependent Libraries : 
@app.route('/', methods=['GET', 'POST'])
def index():
    x = 4
    if request.method == 'POST':
        data = request.form.getlist('a', type=str)
        rslt = ' '.join(data)
    return render_template('index.html', **locals())

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
  </head>
  <body>
    <form method="post">
    {% set ns = namespace(idx=0) %}
    {% for i in range(1,x) %}
      {% for j in range(i+1,x) %}
      <div>
        <label>{{ '{} vs {}'.format(i,j) }}</label>
        <input type="text" name="a" value="{{data and data[ns.idx]}}" />
      </div>
      {% set ns.idx = ns.idx + 1 %}
      {% endfor %}
    {% endfor %}
      <input type="submit" />
    </form>
    {% if rslt %}
    <output>{{ rslt }}</output>
    {% endif %}
  </body>
</html>

from itertools import combinations

@app.route('/', methods=['GET', 'POST'])
def index():
    if request.method == 'POST':
        data = request.form.getlist('a', type=str)
        rslt = ' '.join(data)
    x = 4
    pairs = combinations(range(1,x), 2)
    return render_template('index.html', **locals())

<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title></title>
  </head>
  <body>
    <form method="post">
      {% for i,j in pairs %}
      <div>
        <label>{{ '{} vs {}'.format(i,j) }}</label>
        <input type="text" name="a" value="{{data and data[loop.index0]}}" />
      </div>
      {% endfor %}
      <input type="submit" />
    </form>
    {% if rslt %}
    <output>{{ rslt }}</output>
    {% endif %}
  </body>
</html>

Instructions

Follow the steps carefully to get the output easily.

  1. Download and Install the PyCharm Community Edition on your desktop.
  2. Install flask and itertools on your IDE from python interpreter in setting options.
  3. Create new python file on your IDE.
  4. Copy the snippet using the 'copy' button and paste(till line no 7) it in your python file.
  5. By clicking on the topic we get html code,copy and paste this code into html file(index.html).Create first template folder,inside this we have to create index.html file.
  6. Import flask and itertools.Create app object.
  7. Add app.run statement to the end.
  8. Run the current file to generate the output.


I hope you found this useful. I have added the link to dependent library, version information in the following sections.


I found this code snippet by searching for ' Create for and if loop for inputs in flask ' in kandi. You can try any such use case!

Environment Tested

I tested this solution in the following versions. Be mindful of changes when working with other versions.

  1. PyCharm Community Edition 2022.3.1
  2. The solution is created in Python 3.11.1 Version
  3. flask 2.2.2 Version
  4. jinja2- 3.1.2 version


Using this solution, we can Create for and if loop for inputs in flask.This process also facilities an easy to use, hassle free method to create a hands-on working version of code in python which would help us to Create for and if loop for inputs in flask.

Dependent Libraries

flaskby pallets

Python doticonstar image 63300 doticonVersion:2.2.5doticon
License: Permissive (BSD-3-Clause)

The Python micro framework for building web applications.

Support
    Quality
      Security
        License
          Reuse

            flaskby pallets

            Python doticon star image 63300 doticonVersion:2.2.5doticon License: Permissive (BSD-3-Clause)

            The Python micro framework for building web applications.
            Support
              Quality
                Security
                  License
                    Reuse

                      jinjaby pallets

                      Python doticonstar image 9285 doticonVersion:3.1.2doticon
                      License: Permissive (BSD-3-Clause)

                      A very fast and expressive template engine.

                      Support
                        Quality
                          Security
                            License
                              Reuse

                                jinjaby pallets

                                Python doticon star image 9285 doticonVersion:3.1.2doticon License: Permissive (BSD-3-Clause)

                                A very fast and expressive template engine.
                                Support
                                  Quality
                                    Security
                                      License
                                        Reuse

                                          If you do not have flask library that is required to run this code, you can install it by clicking on the above link.

                                          You can search for any dependent library on kandi like flask and jinja.

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