Expand last value of string column to groupby Pandas Dataframe - python-3.x

Question

I have the following Pandas dataframe:
+--------+----+
|id |name|
+--------+----+
| 1| |
| 1| |
| 1| |
| 1|Carl|
| 2| |
| 2| |
| 2|John|
+--------+----+
What I want to achieve is to expand the last value of each group to the rest of the group:
+--------+----+
|id |name|
+--------+----+
| 1|Carl|
| 1|Carl|
| 1|Carl|
| 1|Carl|
| 2|John|
| 2|John|
| 2|John|
+--------+----+
It looks pretty easy but I am struggling to achieve it because of the columns' type.
What I've tried so far is:
df['name'] = df.groupby('id')['name'].transform('last')
This works for int or float columns, but not for string columns.
I am getting the following error:
No numeric types to aggregate
Thanks in advance.
Edit
bfill() is not valid because I can have the following:
+--------+----+
|id |name|
+--------+----+
| 1| |
| 1| |
| 1| |
| 1|Carl|
| 2| |
| 2| |
| 2| |
| 3| |
| 3| |
| 3|John|
+--------+----+
In this case, I want id = 2 to remain as NaN, and it would end up as John, which is incorrect. The desired output would be:
+--------+----+
|id |name|
+--------+----+
| 1|Carl|
| 1|Carl|
| 1|Carl|
| 1|Carl|
| 2| |
| 2| |
| 2| |
| 3|John|
| 3|John|
| 3|John|
+--------+----+

Answer 1

If the empty values are NaN, could you try fillna
df['name'] = df['name'].bfill()
If not, replace empty strings by NaN.

Answer 2

Try this.
import pandas as pd
import numpy as np
dff = pd.DataFrame({"id":[1,1,1,1,2,2,2,3,3,3],
"name":["","","","car1","","","","","","john"]})
dff = dff.replace(r'', np.NaN)
def c(x):
if sum(pd.isnull(x)) != np.size(x):
l = [v for v in x if type(v) == str]
return [l[0]]*np.size(x)
else:
return [""]*np.size(x)
df=dff.groupby('id')["name"].apply(lambda x:c(list(x)))
df = df.to_frame().reset_index()
df = df.set_index('id').name.apply(pd.Series).stack().reset_index(level=0).rename(columns={0:'name'})
output
id name
0 1 car1
1 1 car1
2 1 car1
3 1 car1
0 2
1 2
2 2
0 3 john
1 3 john
2 3 john