Can Peewee use highlight(), which is SQLite's FTS5 (full text search) auxiliary function?

Question

1. SQLite's FTS5 supports highlight(). That auxiliary function returns tags for results from full text search queries: see the official documentation.

2. Peewee's code on Github, in the <sqlite_ext.py> module also mentions highlight(), although in passing.

   Built-in auxiliary functions:

   • bm25(tbl[, weight_0, ... weight_n])
   • highlight(tbl, col_idx, prefix, suffix)
   • snippet(tbl, col_idx, prefix, suffix, ?, max_tokens)

3. I've found no example code or reference in Peewee's documentation to highlight(), even though Peewee already has support for bm25() and rank() as present FTS5 auxiliary functions.

4. Unless I've missed something, how do I use FTS5 highlight() with Peewee in my Python code? (I'm using Django, if that matters.)

Answer 1

Yeah, just select fn.highlight(...) within a full-text search query.

class Post(FTS5Model):
    title = SearchField()
    content = SearchField()
    class Meta:
        database = db

db.create_tables([Post])

Post.create(title='alpha', content='this is post alpha')
Post.create(title='beta', content='this is post beta')
Post.create(title='delta', content='this is post delta')

query = (Post
         .select(fn.highlight(Post._meta.entity, 1, '[', ']').alias('hi'))
         .where(Post.match('post')))
print(query.sql())
for row in query:
    print(row.hi)

Note that we have to use Post._meta.entity as the first argument, to avoid using the table's alias - Sqlite is particular about using the FTS table name explicitly.

Prints:

this is [post] alpha
this is [post] beta
this is [post] delta