Personal Catalogue: Django & PostgreSQL — Chapter 7, Exercise 2
====================================================

TASK
Switch to the PostgreSQL full-text search version, add an item titled
"Learning Python Programming", and confirm a search for "programmer"
(not "programming") still finds it — then explain why icontains alone
would not have.

SOLUTION

1. Add 'django.contrib.postgres' to INSTALLED_APPS in settings.py.

2. Replace the search portion of get_queryset() with the full-text
   search version from the chapter:

    from django.contrib.postgres.search import SearchVector, SearchQuery, SearchRank

    query = self.request.GET.get('q')
    if query:
        search_query = SearchQuery(query)
        queryset = queryset.annotate(
            search=SearchVector('title', 'creator'),
            rank=SearchRank(SearchVector('title', 'creator'), search_query),
        ).filter(search=search_query).order_by('-rank')

3. Add a real item titled "Learning Python Programming" (any creator,
   any item type - a book fits the title naturally).

4. Search for "programmer" via /?q=programmer. The item should appear
   in the results, even though its actual stored title contains
   "Programming", not "programmer".

WHY icontains WOULD NOT HAVE FOUND IT

title__icontains='programmer' performs a literal substring match -
it checks whether the exact character sequence "programmer" appears
anywhere inside the title field, ignoring case. The stored title is
"Learning Python Programming" - the substring "programmer" (with an
"er" ending) genuinely does not appear anywhere inside "Programming"
(with an "ing" ending), so a plain icontains lookup would correctly,
but unhelpfully, report no match.

WHY POSTGRESQL FULL-TEXT SEARCH DOES FIND IT

PostgreSQL's full-text search doesn't match raw substrings - it applies
real linguistic stemming, reducing words to a common root form before
comparing. Both "programming" and "programmer" stem from the same root
("program"), so PostgreSQL's search engine recognizes them as related
forms of the same underlying word and matches the query against the
stored title despite the literal spellings being different.

ANSWER: icontains performs a literal substring match, and the exact
character sequence "programmer" does not appear inside the stored word
"Programming" - so it correctly finds no match. PostgreSQL's full-text
search instead reduces both words to a shared linguistic root through
stemming, recognizing "programmer" and "programming" as related forms
of the same underlying word, which is why only the full-text search
version successfully finds the item.

WHY THIS WORKS AS AN ANSWER
----------------------------
It uses a real, specific word pair to demonstrate the exact linguistic
distinction (a differing suffix that breaks substring matching but not
stemming-based matching), rather than asserting the two search methods
differ without showing a concrete case where the difference actually
matters.