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Render an editable table using Flask, Jinja2 templates, then process the form data returned

I'm using Flask and Jinja2 and I need to make an editable table with multiple rows.

This is what the table will look like:

img

And here's HTML for that:

<form action="/support/team-members-update" method="post">
<table>
  <tbody><tr>
    <th>Name</th>
    <th>Id</th>
    <th>Inbox Share</th>
  </tr>
  <tr>
    <td>Ben</td><td>55555</td><td><input type="text" name="share_55555" value="0"></td></tr>  <tr>
    <td>Steve</td><td>66666</td><td><input type="text" name="share_66666" value="1"></td></tr> <tr>
    <td>Harry</td><td>77777</td><td><input type="text" name="share_77777" value="1"></td></tr>  <tr>
    <td>Sally</td><td>88888</td><td><input type="text" name="share_88888" value="1"></td></tr></tbody></table>
  <button type="submit">Send</button>
</form>

My current implementation is in Lua, where I'm hard coding a bunch of strings and connecting up the post data to native Lua types by hand (fun!). If I have to, I can process the form data by hand in Python as well, but I imagine there's probably a better solution out there.


I have explored WTForms a bit, but haven't had much luck getting it to work correctly.

I did find FieldList, but that seems to deal with a list of the same field, not multiple rows with the same exact fields.

I also found TableWidget, but the documentation is sparse and I can't figure out how to implement it to know if that would do what I'm looking to do.

like image 918
Ben McCormack Avatar asked Apr 08 '15 00:04

Ben McCormack


Video Answer


2 Answers

FieldList will work, you need to make a list of a FormField. Specify your FormField like so:

class MemberForm(Form):
    name = StringField('name')
    member_id = StringField('member_id')
    inbox_share = IntegerField('inbox_share')
    # etc.

class TeamForm(Form):
    title = StringField('title')
    teammembers = FieldList(FormField(MemberForm))

Then you can create the forms from your database in a view function like so:

@app.route('/support/team-members-update', methods=['GET','POST'])
def update_team_members():
    teamform = TeamForm()
    teamform.title.data = "My Team" # change the field's data
    for member in DB.get('teammembers') # some database function to get a list of team members
        member_form = MemberForm()
        member_form.name = member.name # These fields don't use 'data'
        member_form.member_id = member.id
        member_form.inbox_share = member.share

        teamform.teammembers.append_entry(member_form)

    return render_template('edit-team.html', teamform = teamform)

And then in the template, you can iterate over each item in teammembers as you create your table rows:

<html>
    <head>
        <title>Edit Team Members</title>
    </head>
    <body>
        <h1>Edit Team</h1>
        <div>
            <form action="" method="post" name="teamform">
                {{ teamform.hidden_tag() }}
                Team Title: {{ teamform.title }}<br>
                <div>
                    <table>
                        <tr>
                            <th> Name </th>
                            <th> ID </th>
                            <th> Inbox Share </th>
                        </tr>
                        {% for member in teamform.teammembers %}
                        <tr>
                            <td>{{ member.name }}</td>
                            <td>{{ member.member_id }}</td>
                            <td>{{ member.inbox_share }}</td>
                        </tr>
                        {% endfor %}
                    </table>
                </div>
                <p><input type="submit" name="edit" value="Send"></p>
            </form>
        </div>
    </body>
</html>
like image 182
Aaron D Avatar answered Oct 07 '22 23:10

Aaron D


I never was able to get WTForms to work quite how I wanted. I think it was a bit too heavy for my needs, so I ended up just using my own Jinja2 template to build the form and then used the formencode library to parse the post variables into a dict. This works well enough for me. (Thanks to this question for pointing me to the formencode library).

I'll give you a rough look at the various files I'm using and then explain the important parts at the bottom:

app.py:

from flask import Flask, render_template, request
from formencode import variabledecode
import pickledb

app = Flask(__name__)   

DB = pickledb.load('data/data.db', False)

@app.route('/team-members', methods=['GET', 'POST'])
def team_members():
  global DB
  teammembers = DB.get('teammembers')
  # teammembers looks like this, roughly:
  # [{"id": 55555, "name": "Ben", "share": 0},
  #  {"id": 66666, "name": "Amy", "share": 1},
  #  {"id": 77777, "name": "Ted", "share": 1}] 

  if request.method == 'POST':    
    postvars = variabledecode.variable_decode(request.form, dict_char='_')
    for k, v in postvars.iteritems():
      member = [m for m in teammembers if m["id"] == int(k)][0]
      member['share'] = v["share"]
    DB.set('teammembers', teammembers)
    DB.dump()
  return render_template('team-members.html', teammembers=teammembers) 

if __name__ == '__main__':
    import argparse
    parser = argparse.ArgumentParser()
    parser.add_argument('--debug', '-d', action='store_true')
    parser.add_argument('--port', '-p', default=5000, type=int)
    parser.add_argument('--host', default='0.0.0.0')

    args = parser.parse_args()
    app.run(args.host, args.port, debug=args.debug)

I have three template files, but you of course don't need this many. team-members.html has the code that's relevant to this problem.

_formhelpers.html:

{% macro render_input(id, fieldname, value) %}<input type="text" name="{{ id  }}_{{ fieldname }}" value="{{ value }}" />{% endmacro %}

layout.html:

<!doctype html>
<html>
<head>
  <title>Support Team Site</title>
</head>
<body>
<div class="page">
  <h1>Support Team Site</h1>
  {% for message in get_flashed_messages() %}
    <div class=flash>{{ message }}</div>
  {% endfor %}
  {% block body %}{% endblock %}
</div>
</body>
</html>

team-members.html:

{% from "_formhelpers.html" import render_input %}

{% extends "layout.html" %}
{% block body %}

  <form action="/team-members" method="post">
    <table>
      <tr>
        <th>Name</th>
        <th>ID</th>
        <th>Inbox Share</th>
      </tr>
      {% for member in teammembers %}
      <tr>
        <td>{{member['name']}}</td>
        <td>{{member['id']}}</td>
        <td>{{ render_input(member['id'], 'share', member['share']) }}</td>
      </tr>
      {% endfor %}
    </table>
    <button type="submit">Send</button>
  </form>

{% endblock %}

This will render the following HTML:

<!doctype html>
<html>
<head>
  <title>Support Team Site</title>
</head>
<body>
<div class="page">
  <h1>Support Team Site</h1>



  <form action="/team-members" method="post">
    <table>
      <tr>
        <th>Name</th>
        <th>ID</th>
        <th>Inbox Share</th>
      </tr>

      <tr>
        <td>Ben</td>
        <td>55555</td>
        <td><input type="text" name="55555_share" value="0" /></td>
      </tr>

      <tr>
        <td>Amy</td>
        <td>66666</td>
        <td><input type="text" name="66666_share" value="1" /></td>
      </tr>

      <tr>
        <td>Ted</td>
        <td>77777</td>
        <td><input type="text" name="77777_share" value="1" /></td>
      </tr>

    </table>
    <button type="submit">Send</button>
  </form>


</div>
</body>
</html>

It's worth mentioning what's going on in the if request.method == 'POST': part of app.py. The request.form variable will be of type ImmutableMultiDict, which would look kind of like this when printed out:

ImmutableMultiDict([('55555_share', u'0'), ('66666_share', u'1'), ('77777_share', u'1')])

This is somewhat useful, but we'd still have to parse this by hand to do anything with it. Note the format of the keys there, in the id_fieldname format (e.g. 55555_share). This was thanks to the render_input macro we put in our _formhelpers.html template file. When we process the post form input, we use variabledecode.variable_decode(request.form, dict_char='_'), which parses the form data and turns it into a dictionary based on the naming convention we used for the name values of the form inputs. Here's what it looks like:

{
    "55555": {
        "share": "0"
    },
    "66666": {
        "share": "1"
    },
    "77777": {
        "share": "1"
    }
}

This makes it easy to map back to our original data and update it.

like image 38
Ben McCormack Avatar answered Oct 08 '22 00:10

Ben McCormack