Add AND operator for joining terms

As was mentioned in #261 lunr.js currently doesn’t support joining search terms with AND. It can has interface similar to what Elasticsearch has. You specify what is default operator (OR or AND) and the terms are joined with the specified operator. Otherwise it can look similar to this:

index.query(function(q) {
    q.terms('AND')
       .term('hello', fields: ['field1'], boost: 10)
       .term('world', fields: ['field2'], boost: 1);

    q.terms('OR')
       .term('term1')
       .term('term2');
});

Or with .search() it can look like this:

index.search('term1 term2', { operator: 'AND'} )

Or more sophisticated with new modified query syntax:

index.search('term1 AND term2 OR term3')

What do you think?

[olivernn]

Sorry for the lack of updates on this (and other) issues, my son was born at the end of last year so I haven’t had a lot of free time recently 😅

I did push a branch with the changes to support this, its all there apart from the additions to the search string parser. So you can programatically construct queries with lunr.Index#query to test it out.

I’ll put together a WIP PR with a bit more detail to help people try out what is there currently, getting some feedback would be good. Thanks for the patience on this feature too!

[hafffe]

Any updates on this? would love to see this feature!