AttributeError: 'list' object has no attribute 'first'

Question

lebel_months = []
members_exps = []  

for member in team.members.all():
    qs = Profile.objects.expenses_per_month(member.user)
    clr = color_picker()
    member_qs = []
    for exp in qs:
        user = get_object_or_404(User, id=exp.user_id)
        month = exp.month
        summary = exp.sum
        if month not in lebel_months and month is not None:
            lebel_months.append(month)
        if month is not None and summary is not None:                
            member_qs.append({
                'user': user.username, 
                'clr': clr, 
                'month': month, 
                'summary': summary})
    if member_qs:
        members_exps.append(member_qs)

print(members_exps[0])
print(members_exps.first())

outputs: with [0] everything works

[{'user': 'serj', 'clr': '#71CABC', 'month': datetime.datetime(2020, 3, 1, 0, 0, tzinfo=<UTC>), 
'summary': 128400}, {'user': 'serj', 'clr': '#71CABC', 'month': datetime.datetime(2020, 4, 1, 0, 0, 
tzinfo=<UTC>), 'summary': 53500}]

with first()

AttributeError: 'list' object has no attribute 'first'

First print statement works. Second print statement catch an error. What am I doing wrong?

What do you expect this code to do? The error message clearly describes what happens: `members_exps` is a list, which doesn't have a `first` method. — SuperStormer, Apr 04 '20 at 02:03
I wanted get information like `members_exps.first.user` and it's not work — Serikzhan Naviy, Apr 04 '20 at 02:09
It doesn't work because `members_exp` doesn't have a `first` method. — SuperStormer, Apr 04 '20 at 02:10
Ok. thanks. I understood. How can I get 'user' useing `members|first|first` in template? — Serikzhan Naviy, Apr 04 '20 at 02:22
@hpaulj, this is also my question, did you ever get am answer? — Clement Osei Tano, Jun 16 '21 at 17:25
@ClementOseiTano, one of the answers says `pandas` dataframes have a `first` method, which is easily verified. That said, I don't see evidence that the OP is using pandas. — hpaulj, Jun 16 '21 at 18:36
@hpaulj I later found out the the object I needed was a Queryset — Clement Osei Tano, Jun 17 '21 at 16:28

score 0 · Answer 1 · answered Apr 04 '20 at 02:04

0

As the error says, the members_exps variable is a list, and in python lists do not have a first() attribute/function. first only works for dataframes.

answered Apr 04 '20 at 02:04

score 0 · Accepted Answer · answered Apr 04 '20 at 02:20

0

Firstly, members_exps = [] declares List type.

Lists/Arrays don't have a first() method. There's a list of available methods: https://www.w3schools.com/python/python_ref_list.asp

If you want to get the first item of the List you might be interested to read the following thread: Python idiom to return first item or None

answered Apr 04 '20 at 02:20

Viktor Born

186
1
5

> Lists/Arrays don't have a first() method. Indeed, because why would you ever want such a method? Perhaps in Python 4; after all, Python finally got a switch statement in 3.10 after 30 years. – michael_teter Mar 31 '22 at 08:29

AttributeError: 'list' object has no attribute 'first'

2 Answers2