ReportLab get_FOO_display() Not Working On A List

Question

Ive created a form which users fill out, then it uses reportlab to create a pdf of their answers.

It works well except for a charfield (preferred_topics) which contains a list. Data is saved like this:

['ANI', 'EDU', 'ENV']

I think that might be a problem as id exect it to save the data like this:

[['ANI'], ['EDU'], ['ENV']]

However it works fine on the website.

So to print human readable data to the pdf im using get_FOO_display(), but this doesnt work for preferred_topics. If i call (user.personalinformation.get_preferred_topics_display() i get:

AttributeError at /enrolment/final_question/
'PersonalInformation' object has no attribute 'get_preferred_topics_display'

Here is my other relevant code:

model.py

preferred_topics = models.CharField(max_length=200, default='')

utils.py

# generate pdf
def generate_pdf(request):
    # get user
    user = request.user

    # data that will be printed to the pdf
    page_contents = [
        ['Personal Information'],
        ['Name:', '%s %s' %(user.personalinformation.first_name, user.personalinformation.surname)],
        ['E-mail:', '%s' %(user.email)],
        ['Gender:', '%s' %(user.personalinformation.get_gender_display())],
        # this field is causing grief
        ['Preferred Topics:', '%s' %(user.personalinformation.preferred_topics)]
    ]

forms.py

TOPICS = (
        ('ANI', 'Animals'),
        ('ART', 'Art'),
        ('COM', 'Communication'),
        ('CRI', 'Crime'),
    )

    preferred_topics = forms.MultipleChoiceField(choices=TOPICS, required=False, widget=forms.CheckboxSelectMultiple())

Im expecting to be told that the data is being saved wrongly in my db, but dont know how to change it, and wanted confirmation before i started changing previously working stuff as im sure i will break currently working things in the process.

SUMMARY - i want to use user.personalinformation.get_preferred_topics_display() but its not working and i suspect its because the data is being saved wrongly in the db but would like confirmation before i go wrecking stuff.

Thank you.

Answer 1

You are saving multiple choices as single string which is not good idea as you would have hard time filtering and working with this kind of data ( rather use Arrayfield of choices)

There is no get_FOO_display() without choices on models field so you would need to write your own converter

# create dict of options
options = dict((y,x) for y,x in PersonalInformationForm.TOPICS)

# evaluate string to list
selected_choices = ast.literal_eval(testobj2.preferred_topics)

# find choices in dict
selected values = [option.get(key) for key in selected_choices]