Full Text Search

Couchbase Lite ^[1] supports Full Text Search (FTS). FTS is accomplished using the match query. FTS matches are case-sensitive. In the Travel App, the FTS query is against local "travel-sample" documents that is pre-built with the app.

In order to do FTS queries, an FTS index must be created.

Open the fileHotelsDao.java. We will review the searchHotelsAsync() method. This code snippet creates an FTS index on the property named description.

HotelsDao.java

  @Nonnull
    private List<Hotel> searchHotelsAsync(@Nonnull String location, @Nonnull String desc) {
        ...
    }

    final ResultSet results = QueryBuilder
        .select(SelectResult.expression(Meta.id), SelectResult.all())
        .from(DataSource.database(db.getDatabase()))
        .where(Expression.property(DbManager.PROP_DOC_TYPE).equalTo(Expression.string(Hotel.DOC_TYPE))
        .and(FullTextExpression.index(DbManager.FTS_INDEX_DESC).match(desc)
            .and(Expression.property(Hotel.PROP_ADDRESS).like(Expression.string(loc))
            .or(Expression.property(Hotel.PROP_CITY).like(Expression.string(loc)))
            .or(Expression.property(Hotel.PROP_STATE).like(Expression.string(loc)))
            .or(Expression.property(Hotel.PROP_COUNTRY).like(Expression.string(loc))))))
            .orderBy(Ordering.property(Hotel.PROP_NAME).ascending())
            .execute();

This is a fairly involved query expression.

You will create an FTS Expressions using the match() operator. In this particular example, the match expression looks for the desc value in the description property.
This match expression is logically ANDed with an equalTo comparison expression which looks for the location in the country,city,state or address properties.
This expression is then used in the where clause of the query the usual way.

We build the query using the different expressions from above and parse the ResultSet object into a List<Hotel> object

  for (Result result : results.allResults()) {
            if (result.count() < 2) { continue; }
            final Hotel hotel = Hotel.fromDictionary(result.getString(0), result.getDictionary(1));
            if (hotel != null) { hotels.add(hotel); }
        }

Try it out

Log into the Travel Sample Mobile app as “demo” user and password as “password”
Tap on "hotels" button
In the description text field enter “Pets”.
In the Location text field enter "London" (Note the search is case sensitive)
Verify that you see one hotel listed named "Novotel London West" — see Figure 1

Figure 1. Hotel List

1. From 2.0