Can I multiply the boost by a score in a field?

[reubenfirmin]

Let's say I have document:

doc {
   content: string;
   baseScore: int;
}

I could post-process the results and reorder by multiplying in baseScore, but is there a way to do that as part of the query?

Or, alternately, could I do something like:

doc {
   content: string;
   primary: boolean;
}

...and tell minisearch to boost by X where primary==true?

The one way I can think of to do this is to:

doc {
   content: string;
   forfiltering: string;
}

Then when I index, I set forfiltering to some unique string, e.g. "thzzz", include that term in all of my queries, and boost forfiltering. But that's hacky, so I'm looking for something more elegant.

[lucaong]

Hi @reubenfirmin , yes, there is a clean way to boost specific documents based on the value of a field, by using the boostDocument search option:

// Say that your documents look like this:
const documents = [
  {
    id: 1,
    text: 'Some example text',
    boostFactor: 1.5
  },
  {
    id: 2,
    text: 'Some other example text',
    boostFactor: 0.9
  },
  {
    id: 3,
    text: 'Some more example text',
    boostFactor: null
  }
]

// Keep a map of documents by their ID:
const docById = documents.reduce((byId, doc) => {
  byId[doc.id] = doc
  return doc
}, {})

// Initialize MiniSearch as usual
const miniSearch = new MiniSearch({ fields: ['text'] })

// Upon search, use the `boostDocument` search option to specify a dynamic boosting factor:
miniSearch.search('example', {
  boostDocument: (docId) => docById[docId].boostFactor || 1
})

A boost of 1 is neutral, a boost > 1 increases the score of a result, and < 1 decreases it.

[reubenfirmin]

Awesome! Does this run over the results prior to returning them?

Any chance you could extend this by giving the option to pass the SearchResult itself to the function? I have too many documents to keep a separate map of them, so I'm going to be looking them up in minisearch, which seems redundant.

That way I could store fields that get passed in at the time of sorting; e.g.

   boostResult: (result) => (result.special) ? 2 : 1

[lucaong]

At the moment, only the document ID and the matched term are passed to the boostDocument callback, but I will soon make a new release that will make the storeFields fields available. You will soon be able to do something like this:

// Initialize MiniSearch as usual
const miniSearch = new MiniSearch({
  fields: ['text'],
  storeFields: ['text', 'boostFactor']
})

// Upon search, use the `boostDocument` search option to specify a dynamic boosting factor:
miniSearch.search('example', {
  boostDocument: (docId, term, storedFields) => storedFields.boostFactor || 1
})

This pull request implements the feature.

[lucaong]

Version v6.1.0 is published on NPM, including this feature. I am therefore closing this issue, but feel free to add further comments if necessary.

[reubenfirmin]

Thanks! This is great.