# Autosuggest

Generate autocomplete suggestions based on what your users search

:tangerine: Battle-tested at [Instacart](https://www.instacart.com/opensource)

[![Build Status](https://github.com/ankane/autosuggest/workflows/build/badge.svg?branch=master)](https://github.com/ankane/autosuggest/actions)

## Installation

Add this line to your application’s Gemfile:

```ruby
gem 'autosuggest'
```

## Getting Started

#### Prepare your data

Start with a hash of queries and their popularity, like the number of users who have searched it.

```ruby
top_queries = {
  "bananas" => 353,
  "apples"  => 213,
  "oranges" => 140
}
```

With [Searchjoy](https://github.com/ankane/searchjoy), you can do:

```ruby
top_queries = Searchjoy::Search.group(:normalized_query)
  .having("COUNT(DISTINCT user_id) >= 5").distinct.count(:user_id)
```

Then pass them to Autosuggest.

```ruby
autosuggest = Autosuggest.new(top_queries)
```

#### Filter duplicates

[Stemming](https://en.wikipedia.org/wiki/Stemming) is used to detect duplicates like `apple` and `apples`.

The most popular query is preferred by default.  To override this, use:

```ruby
autosuggest.prefer ["apples"]
```

To fix false positives, use:

```ruby
autosuggest.not_duplicates [["straws", "straus"]]
```

#### Filter misspellings

We tried open-source libraries like [Aspell](http://aspell.net) and [Hunspell](http://hunspell.sourceforge.net/) but quickly realized we needed to build a corpus specific to our application.

There are two ways to build the corpus, which can be used together.

1. Add words

  ```ruby
  autosuggest.parse_words Product.pluck(:name)
  ```

  Use the `min` option to only add words that appear multiple times.

2. Add concepts

  ```ruby
  autosuggest.add_concept "brand", Brand.pluck(:name)
  ```

#### Filter words

[Profanity](https://github.com/tjackiw/obscenity/blob/master/config/blacklist.yml) is blocked by default. Add custom words with:

```ruby
autosuggest.block_words ["boom"]
```

#### Generate suggestions

Generate suggestions with:

```ruby
suggestions = autosuggest.suggestions(filter: true)
```

#### Save suggestions

Save suggestions in your database or another data store.

With Rails, you can generate a simple model with:

```sh
rails generate autosuggest:suggestions
rails db:migrate
```

And update suggestions with:

```ruby
now = Time.now
records = suggestions.map { |s| s.slice(:query, :score).merge(updated_at: now) }
Autosuggest::Suggestion.transaction do
  Autosuggest::Suggestion.upsert_all(records, unique_by: :query)
  Autosuggest::Suggestion.where("updated_at < ?", now).delete_all
end
```

Leave out `unique_by` for MySQL, and use [activerecord-import](https://github.com/zdennis/activerecord-import) for upserts with Rails < 6.

#### Show suggestions

Use a JavaScript autocomplete library like [typeahead.js](https://github.com/twitter/typeahead.js) to show suggestions in the UI.

If you only have a few thousand suggestions, it’s much faster to load them all at once instead of as a user types (eliminates network requests).

With Rails, you can load all suggestions with:

```ruby
Autosuggest::Suggestion.order(score: :desc).pluck(:query)
```

And suggestions matching user input with:

```ruby
input = params[:query]
Autosuggest::Suggestion
  .order(score: :desc)
  .where("query LIKE ?", "%#{Autosuggest::Suggestion.sanitize_sql_like(input.downcase)}%")
  .pluck(:query)
```

You can also cache suggestions for performance.

```ruby
Rails.cache.fetch("suggestions", expires_in: 5.minutes) do
  Autosuggest::Suggestion.order(score: :desc).pluck(:query)
end
```

#### Additional considerations

You may want to have someone manually approve suggestions:

```ruby
Autosuggest::Suggestion.where(approved: true)
```

Or filter suggestions without results:

```ruby
Autosuggest::Suggestion.find_each do |suggestion|
  suggestion.has_results = Product.search(suggestion.query, load: false, limit: 1).any?
  suggestion.save! if suggestion.changed?
end

Autosuggest::Suggestion.where(has_results: true)
```

You can add additional fields to your model/data store to accomplish this.

## Example

```ruby
top_queries = Searchjoy::Search.group(:normalized_query)
  .having("COUNT(DISTINCT user_id) >= 5").distinct.count(:user_id)
product_names = Product.pluck(:name)
brand_names = Brand.pluck(:name)

autosuggest = Autosuggest.new(top_queries)
autosuggest.parse_words product_names
autosuggest.add_concept "brand", brand_names
autosuggest.prefer brand_names
autosuggest.not_duplicates [["straws", "straus"]]
autosuggest.block_words ["boom"]

suggestions = autosuggest.suggestions(filter: true)

now = Time.now
records = suggestions.map { |s| s.slice(:query, :score).merge(updated_at: now) }
Autosuggest::Suggestion.transaction do
  Autosuggest::Suggestion.upsert_all(records, unique_by: :query)
  Autosuggest::Suggestion.where("updated_at < ?", now).delete_all
end
```

## History

View the [changelog](https://github.com/ankane/autosuggest/blob/master/CHANGELOG.md)

## Contributing

Everyone is encouraged to help improve this project. Here are a few ways you can help:

- [Report bugs](https://github.com/ankane/autosuggest/issues)
- Fix bugs and [submit pull requests](https://github.com/ankane/autosuggest/pulls)
- Write, clarify, or fix documentation
- Suggest or add new features

To get started with development:

```sh
git clone https://github.com/ankane/autosuggest.git
cd autosuggest
bundle install
bundle exec rake test
```