Ktor

One of the core design goals of GraphQLize is not to tie to any web development framework and remain as a drop-in JVM library.

Getting started with GraphQLize in Ktor is simple and involves only a few steps.

Adding Dependencies

Let's start with creating a new Ktor Project using Gradle & Netty. Under Server settings, select Jackson & Content Negotiation.

Then in the created project add the graphqlize-java & the JDBC driver dependencies.

Clojars Project

// ...
repositories {
// ...
maven { url "https://clojars.org/repo" }
}
// ...
dependencies {
// For Postgres
implementation 'org.postgresql:postgresql:42.2.10'
// For MySQL
implementation 'mysql:mysql-connector-java:8.0.19'
implementation 'org.graphqlize:graphqlize-java:0.1.0-alpha19'
// DB Connection Pooling
implementation 'com.zaxxer:HikariCP:3.4.2'
// ...
}

Initializing GraphQLizeResolver

To initialize GraphQLizeResolver, we need a DataSource.

Configuring DataSource

// Application.kt
package org.graphqlize
// ...
import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
fun getDataSource(): HikariDataSource {
val config = HikariConfig()
config.setJdbcUrl("jdbc:postgresql://localhost:5432/sakila");
config.setUsername("postgres");
config.setPassword("postgres");
return HikariDataSource(config)
}
// ...
fun Application.module(testing: Boolean = false) {
val dataSource = getDataSource()
// ...
}
note

Make sure you are changing the above values to refer your database connection. The above example assumes that you are using the sakila database created from this JOOQ's example repository.

With the data source in place, all we need to do is the create a new instance of GraphQLizeResolver using it.

// ...
import org.graphqlize.java.GraphQLResolver;
import org.graphqlize.java.GraphQLizeResolver;
// ...
fun Application.module(testing: Boolean = false) {
// ...
val graphQLResolver = GraphQLizeResolver(dataSource)
}
note

Currently, it takes around 8 to 12 seconds to initialize. I am planning to work on it in a future release.

Adding GraphQL Endpoint

The next step is adding an API to expose the GraphQL endpoint. To do it, first, add a data class to model the incoming GraphQL request.

// ...
import com.fasterxml.jackson.annotation.JsonCreator
// ...
data class GraphQLRequest @JsonCreator constructor(
val query: String,
val variables: Map<String, Any>?
)
// ...

Then add a new router /graphql and deserialize the request to this GraphQLRequest class using Jackson. Finally, get the query & the variables from the request and invoke the resolve method on the initialized instance of GraphQLizeResolver. It returns the result as stringified JSON, and we are sending it as response body with the content type as application/json.

// ...
import com.fasterxml.jackson.databind.DeserializationFeature
// ...
fun Application.module(testing: Boolean = false) {
val dataSource = getDataSource()
val graphQLResolver = GraphQLizeResolver(dataSource)
install(ContentNegotiation) {
jackson {
disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
}
}
routing {
post("/graphql") {
val gqlReq = call.receive<GraphQLRequest>()
val result =
graphQLResolver.resolve(gqlReq.query, gqlReq.variables)
call.respondText(result, ContentType.Application.Json)
}
}
}

Test Drive

To do a test drive of this implementation, start the server and hit the endpoint via curl.

> curl -X POST \
--data '{"query": "query { actorByActorId(actorId: 1){firstName}}"}' \
-H "Content-Type: application/json" \
http://localhost:4567/graphql

You'll get a response like below.

{
"data": {
"actorByActorId": {
"firstName": "PENELOPE"
}
}
}

GraphQL Playground and Voyager

With the GraphQL endpoint up and running, the next step is introspecting the GraphQL schema and try out some more queries.

To introspect, we are going to make use of Voyager, a tool to visualize GraphQL API as an interactive graph. Adding it to our project is easy thanks to static content serve capability of Ktor.

All you need to do is download this voyager.html file and put it under the /resources directory.

Then configure Ktor to serve this file.

// ...
fun Application.module(testing: Boolean = false) {
// ...
routing {
// ...
static("/") {
resource("voyager.html")
}
}
}

When you restart the server, the Voyager will be available at http://localhost:8080/voyager.html. A sample output would look like this.

Then to interact with the GraphQL API, let's add the GraphQL Playground. Like Voyager, download this playground.html file and put in the resources directory.

// ...
fun Application.module(testing: Boolean = false) {
// ...
routing {
// ...
static("/") {
// ...
resource("playground.html")
}
}
}

This GraphQL playground will be available at http://localhost:8080/playground.html after server restart.

Next Steps

Congrats! You are on course to build impressive applications using GraphQLize in less time. To save yourself some more time, do refer this documentation to know more about how GraphQLize generates the GraphQL schema and the queries.

The sample code is available in this GitHub Repository.

note

You can also customize certain default behaviours of GraphQLize in future releases.