Launch GraphOS Studio

3. Write your first query

The most common is the query, which requests data from your in a structure that conforms to your server's schema. If you return to the Sandbox for your server, you can see available queries in the Schema Reference tab you opened earlier.

Scroll down to the launches to get details about it:

Detail about launches query

Here, you see both the term itself, the return type, and information about parameters that can be passed to the query. You can use this information to write a query you'll eventually add to your app.

To start working with this in the Sandbox Explorer, select the "play" button to the right side of the information:

Open in Explorer

This brings you back into Sandbox's Explorer tab with the sidebar on the left showing documentation for the you've selected:

Docs open in the left sidebar

Notice the small button next to the launches icon. Click this button to add the to the middle "" panel:

Click the button to add this query

When the is added, it will look like this:

The query once it's been added to the Operations section

Let's break down what you're seeing here:

  • The type of the , query, followed by the name of the , currently Query (we'll make that more specific in a second), is the outermost set of brackets.
  • The actual being called is the next set of brackets in. Since the arguments for this both have default values, they are not automatically added to the query for you.
  • An error in the empty space between the brackets, which is where you'll put the list of information you want back from each .

The SDK requires every to have a name (even though this isn't required by the spec). Since you're going to create more than one query, it's also a good idea to give this a specific name other than Query. Change the name of the to LaunchList:

Renaming the query

Next, on the left hand side, you can select what you want back in the returned object. Start by clicking the button next to the cursor . It will mark that field as selected, then insert it into your :

After adding the cursor field.

This is probably the easiest way to add to your object, since it knows how everything is spelled and what type everything is.

However, you can also use auto-complete to help you with this. Add a newline below cursor in the panel and start typing ha. An autocomplete box pops up and shows you options based on what's in the schema:

Example of autocomplete

The Sandbox Explorer is a great tool for building and verifying queries so you don't have to repeatedly rebuild your project in Android Studio to try out changes.

As the schema indicates, the launches returns a LaunchConnection object. This object includes a list of , along with related to pagination (cursor and hasMore). The you've written so far indicates exactly which of this LaunchConnection object you want to be returned.

Run this by pressing the "Submit " button, which should now have the name of your query, LaunchList:

Submit the operation

You'll quickly see the returns results as a JSON object on the right-hand side of the page:

Query JSON in Sandbox Explorer

This executes successfully, but it doesn't include any information about the launches! That's because we didn't include the necessary in the .

Click the button next to the launches at the bottom of the left column. It will add a set of braces for launches to the section, and then move the documentation to show information for the Launch type:

Status after adding launches field

The you add in this set of brackets will be fetched for every in the list. Click the buttons next to id and site properties to add those two . When you're done, your should look like this:

(Sandbox Explorer)
query LaunchList {
launches {
launches {

Run the again, and you'll now see that in addition to the information you got back before, you're also getting a list of with their ID and site information:

Updated query JSON in Sandbox Explorer

Add the query to your project

Now that your is fetching the right data, head back to Android Studio.

  1. Right click on the src/main/graphql/ folder. This folder should contain your schema.graphqls. Select New > File:
New GraphQL file
  1. Name the file LaunchList.graphql. Make sure it's saved at the same level as your schema.graphqls file.

  2. Copy your final from Sandbox Explorer and paste it into LaunchList.graphql.

query LaunchList {
launches {
launches {

Generate the model

Build your project to have the plugin generate your first model. The plugin defines a task named generateApolloSources to generate the models. You don't need to run it. It will be executed automatically when building your project.

Note: Autocomplete won't work until you build your project. That is because autocomplete requires the generated code to work. Each time you change your queries, you should rebuild your project for Android Studio to pick up the modifications.

Examine generated code

From the menu, select Navigate > Class and start typing LaunchList, Android Studio should suggest to open LaunchListQuery.kt. The file should be in app/build/generated/source/apollo/service/com/example/rocketreserver/LaunchListQuery.kt.

The LaunchListQuery.kt file defines a root class, LaunchListQuery, with many nested classes. If you compare the classes to the JSON data returned in Sandbox Explorer, you see that the structure matches. These classes include properties only for the that your requests.

Try commenting out the id property in LaunchList.graphql, saving, then building again. When the build completes, the Launch class now only includes the requested site property.

Uncomment id and rebuild to restore the property.

Now that you've generated code and had a chance to see what's in there, it's time to execute the query!

2. Add the GraphQL schema
4. Execute your first query
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