So, is there a simpler way to implement full text search without a third-party service?<\/p>\n\n\n\n
Enter, Hackerman.<\/p>\n\n\n\n If you haven\u2019t already setup Firestore with your project, you can follow the official documentation<\/a> to get started.<\/p>\n\n\n\n Let\u2019s say that we\u2019re building an Android application that lists a set of products available at a grocery shop. To keep things simple, let\u2019s assume that each product has just two fields \u2014 its name and its price.<\/p>\n\n\n\n Here\u2019s how our schema looks like in Firestore, with a root level collection called products<\/em> and each document inside it corresponds to a single grocery item.<\/p>\n\n\n\n Our solution comprises of the following steps:<\/p>\n\n\n\n Before we continue, it\u2019s highly important to understand the limitations of this approach.<\/strong><\/p>\n\n\n\n Understanding these limitations is crucial as these could become major blockers as your application scales.<\/p>\n\n\n\n The keywords array will power our search functionality. When we query Firestore in the next steps, we will check if our search query is contained in the keywords array for any document. Therefore, we want to ensure that our keywords array contains an exhaustive set of entries that cover all possible combinations of the product\u2019s name. There are multiple ways<\/a> to generate these keywords.<\/p>\n\n\n\n Following the first approach, here\u2019s how it looks like when translated to Kotlin:<\/p>\n\n\n\n Here are some keywords generated for \u2014 Premium Filter Coffee 250gm<\/em><\/p>\n\n\n\n Now that we have our data ready, we can add it to Firestore. Each document now has three fields \u2014 name, price and keywords.<\/p>\n\n\n\n and can be added to our database with the following piece of code:<\/p>\n\n\n\n Let\u2019s write a method that returns our database query:<\/p>\n\n\n\n Limits are optional, but recommended, as they throttle our search results and ensure that we don\u2019t accidentally overuse our Firestore free limits \/ budgets.<\/p>\n\n\n\n We can now integrate this method directly with our UI or interface it with a view model. I prefer using the latter approach.<\/p>\n\n\n\n And that\u2019s it!<\/p>\n\n\n\n That\u2019s how we can power full text search in Firestore with its native, out of the box capabilities. However, I would like to reiterate its limitations so you can make the best decision for your application considering the use case and your roadmap.<\/p>\n\n\n\n I would also suggest for you to debounce<\/a> your search listeners, to optimise the number of queries we end up making to the Firestore database.<\/p>\n\n\n\n![\"\"\/](\"https:\/\/miro.medium.com\/max\/1400\/1*dRudObMfI_t9SNzYcpQA9A.jpeg\")
<\/figure>\n\n\n\nThe Use Case<\/h3>\n\n\n\n
![\"\"\/](\"https:\/\/miro.medium.com\/max\/1400\/1*mEdL7WtgT1rx1Qra9ev8-w.png\")
<\/figure>\n\n\n\nSolution Overview<\/h3>\n\n\n\n
keywords<\/code> for each product name<\/li>whereArrayContains<\/code> <\/strong>to power our search functionality<\/li><\/ol>\n\n\n\nwhereArrayContains<\/code><\/li>Generating Keywords<\/h3>\n\n\n\n
fun generateKeywords(name: String): List<String> {<\/strong>
val keywords = mutableListOf<String>()
for (i in 0 until name.length) {
for (j in (i+1)..name.length) {
keywords.add(name.slice(i until j))
}
}
return keywords
}<\/pre>\n\n\n\n![\"\"\/](\"https:\/\/miro.medium.com\/max\/875\/1*iCreA3vtDADB5jZPoyTs5Q.png\")
<\/figure>\n\n\n\ndata class Product (<\/strong>
val name: String,
val price: Double,
val keywords: List<String>
)<\/strong><\/pre>\n\n\n\nFirebase
.firestore
.collection(\"products\")
.add(Product(name, price, generateKeywords(name)<\/strong>)<\/pre>\n\n\n\nQuerying Firestore<\/strong><\/h3>\n\n\n\n
fun getProductsByName(searchQuery: String) =<\/strong> Firebase.firestore
<\/em>.collection(\"products\")
.whereArrayContains(\"keywords\", searchQuery.trim<\/em>())
.limit(50)<\/pre>\n\n\n\nprivate val observer =<\/strong> MutableLiveData<List<Product>>()
fun liveData():<\/strong> LiveData<List<Product>> = observer
fun getProductsByName(searchQuery: String) =<\/strong>
mRepository
.getProductsByName(searchQuery)
.get()
.addOnCompleteListener { <\/strong>task ->
<\/strong>if (task.isSuccessful<\/em>)
observer.postValue(task.result<\/em>.toObjects(Product::class.java<\/em>))
}<\/strong><\/pre>\n\n\n\n