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CHAPTER 12
More Advanced Forms
Now let’s look at some more advanced forms usage. We’ve helped our users to avoid
blank list items, now let’s help them avoid duplicate items.
This chapter goes into more intricate details of Django’s form validation, and you can
consider it optional if you already know all about customising Django forms. If you’re
still learning Django, there’s good stuff in here. If you want to skip ahead, that’s OK too.
Make sure you take a quick look at the aside on developer stupidity, and the recap on
testing views at the end.
Another FT for Duplicate Items
We add a second test method to
ItemValidationTest
:
functional_tests/test_list_item_validation.py (ch12l001).
def
test_cannot_add_duplicate_items
(
self
):
# Edith goes to the home page and starts a new list
self
.
browser
.
get
(
self
.
server_url
)
self
.
get_item_input_box
()
.
send_keys
(
'Buy wellies
\n
'
)
self
.
check_for_row_in_list_table
(
'1: Buy wellies'
)
# She accidentally tries to enter a duplicate item
self
.
get_item_input_box
()
.
send_keys
(
'Buy wellies
\n
'
)
# She sees a helpful error message
self
.
check_for_row_in_list_table
(
'1: Buy wellies'
)
error
=
self
.
browser
.
find_element_by_css_selector
(
'.has-error'
)
self
.
assertEqual
(
error
.
text
,
"You've already got this in your list"
)
Why have two test methods rather than extending one, or having a new file and class?
It’s a judgement call. These two feel closely related; they’re both about validation on the
same input field, so it feels right to keep them in the same file. On the other hand, they’re
logically separate enough that it’s practical to keep them in different methods:
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