Filling WTForms FormField FieldList with data resu

2019-02-01 00:58发布

站内问答 / Python
741 1 6

I have a Flask app in which I can populate form data by uploading a CSV file which is then read. I want to populate a FieldList with the data read from the CSV. However, when I try to populate the data, it enters raw HTML into the TextFields instead of just the value that I want. What am I doing wrong?

app.py

from flask import Flask, render_template, request, url_for
from flask.ext.wtf import Form
from wtforms import StringField, FieldList, FormField, SelectField
from wtforms.validators import DataRequired
from werkzeug.datastructures import MultiDict

app = Flask(__name__)
app.config['SECRET_KEY']='asdfjlkghdsf'

# normally student data is read in from a file uploaded, but for this demo we use dummy data
student_info=[("123","Bob Jones"),("234","Peter Johnson"),("345","Carly Everett"),
              ("456","Josephine Edgewood"),("567","Pat White"),("678","Jesse Black")]

class FileUploadForm(Form):
    pass

class StudentForm(Form):
    student_id = StringField('Student ID', validators = [DataRequired()])
    student_name = StringField('Student Name', validators = [DataRequired()])

class AddClassForm(Form):
    name = StringField('classname', validators=[DataRequired()])
    day = SelectField('classday', 
                      choices=[(1,"Monday"),(2,"Tuesday"),(3,"Wednesday"),(4,"Thursday"),(5,"Friday")],
                      coerce=int)

    students = FieldList(FormField(StudentForm), min_entries = 5) # show at least 5 blank fields by default

@app.route('/', methods=['GET', 'POST'])
def addclass():
    fileform = FileUploadForm()
    classform = AddClassForm()

    # Check which 'submit' button was called to validate the correct form
    if 'addclass' in request.form and classform.validate_on_submit():
        # Add class to DB - not relevant for this example.
        return redirect(url_for('addclass'))

    if 'upload' in request.form and fileform.validate_on_submit():
        # get the data file from the post - not relevant for this example.
        # overwrite the classform by populating it with values read from file
        classform = PopulateFormFromFile()
        return render_template('addclass.html', classform=classform)

    return render_template('addclass.html', fileform=fileform, classform=classform)

def PopulateFormFromFile():
    classform = AddClassForm()

    # normally we would read the file passed in as an argument and pull data out, 
    # but let's just use the dummy data from the top of this file, and some hardcoded values
    classform.name.data = "Super Awesome Class"
    classform.day.data = 4 # Thursday

    # pop off any blank fields already in student info
    while len(classform.students) > 0:
        classform.students.pop_entry()

    for student_id, name in student_info:
        # either of these ways have the same end result.
        #
        # studentform = StudentForm()
        # studentform.student_id.data = student_id
        # studentform.student_name.data = name
        #
        # OR
        student_data = MultiDict([('student_id',student_id), ('student_name',name)])
        studentform = StudentForm(student_data)

        classform.students.append_entry(studentform)

    return classform


if __name__ == '__main__':
    app.run(debug=True, port=5001)

templates/addclass.html

<html>
    <head>
        <title>Flask FieldList Demo</title>
    </head>
    <body>
        <h1>Add Class</h1>
        {% if fileform %}
        <div>
            <p>Add class from file:</p>
            <form action="" method="post" enctype="multipart/form-data" name="fileform">
                {{ fileform.hidden_tag() }}
                <p><input type="submit" name="upload" value="Upload"></p>
            </form>
        </div>
        <hr>
        {% endif %}
        <div>
            <form action="" method="post" name="classform">
                {{ classform.hidden_tag() }}
                Class Name: {{ classform.name }}<br>
                Day: {{ classform.day }}<br>
                <br>
                <div>
                    <table>
                        <tr>
                            <th> Student Number </th>
                            <th> Name </th>
                        </tr>
                        {% for student in classform.students %}
                        <tr>
                            <td>{{ student.student_id }}</td>
                            <td>{{ student.student_name }}</td>
                        </tr>
                        {% endfor %}
                    </table>
                </div>
                <p><input type="submit" name="addclass" value="Add Class"></p>
            </form>
        </div>
    </body>
</html>

The offending code snippet happens at the line classform.students.append_entry(studentform). I can post the output HTML if required. What I expect is something like this: Expected Output What I get instead is: enter image description here

1条回答
放我归山
2楼-- · 2019-02-01 01:43

OK, I spent hours on this and in the end it was such a trivial code change.

Most fields let you change their value by modifying the data attribute (as I was doing above). In fact, in my code, I had this comment as above:

    ### either of these ways have the same end result.
    #
    # studentform = StudentForm()
    # studentform.student_id.data = student_id
    # studentform.student_name.data = name
    #
    ### OR
    #
    # student_data = MultiDict([('student_id',student_id), ('student_name',name)])
    # studentform = StudentForm(student_data)

However, in the case of a FieldList of FormFields, we should not edit the data attribute, but rather the field itself. The following code works as expected:

for student_id, name in student_info:

    studentform = StudentForm()
    studentform.student_id = student_id     # not student_id.data
    studentform.student_name = name

    classform.students.append_entry(studentform)

I hope this helps someone experiencing the same problem.

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