Unity Integration

In the last page, we successfully created all the tables and views we required to introduce matchmaking into our game.

Now, we need to properly interface with that Hasura backend. Go back to your Unity project that contains the boilerplate version of the game.

Setting up the Unity GraphQL client

First off, we'd need a client to simplify communication with the GraphQL Hasura backend.

For this, we shall be using an open source tool called graphql-client-unity

Read the documentation for graphql-client-unity to familiarize yourself with the client.

Download and import the client into your project.

Create an Api Reference as shown in the client documentation and name it appropriately.

Next, we'd need the url for our backend. This can be gotten from the GraphiQL tab in our Hasura backend.

Hasura backend url

After putting the url, we'd need to introspect the backend to let the client know the possible queries, mutations and subscriptions.

Click the Instrospect button and wait a while for the client to get the info it need.

Introspect

Great! Now our graphQL client is set up and we can begin to make queries and subscriptions.

Query Mutations and Subscriptions

Now that we've set up the client with our server, we need to make certain queries, mutations and subscriptions for our matchmaking to work.

Query

For now, we shall create only one query. GetOnlineBattles

query GetOnlineBattles{
    online_battles{
        id
    }
}

To create this in our Api reference

Click Create New Query
Name it GetOnlineBattles
Select online_battles as the query
Click Confirm Query
Create the id field.

Your query should look like this.

GetOnlineBattles

According to our backend, online_battles is a view that returns all open battles that haven't been joined.

Mutations

We shall create 4 mutations.

CreateBattle
UpdateOnlineBattle
DeleteBattle
DeleteOldBattles

CreateBattle

mutation CreateBattle{
    insert_battles{
        returning{
            id
            shooter_id
        }
    }
}

To create this in our Api reference

Click Create New Mutation
Name it CreateBattle
Select insert_battles as the mutation
Click Confirm Mutation
Create the returning field
Create sub-fields id and shooter_id

Your mutation should look like this.

CreateBattle

insert_battles is a mutation that allows us to create a new battle row in our battles table in Hasura.

This would be used to create a battle if no open online battles is found. In accordance to our Matchmaking Flow Chart

UpdateOnlineBattle

mutation UpdateOnlineBattle{
    update_battles{
        returning{
            id
            shooter_id
            defender_id
            shooterReady
            defenderReady
        }
    }
}

To create this in our Api reference

Click Create New Mutation
Name it UpdateOnlineBattle
Select update_battles as the mutation
Click Confirm Mutation
Create the returning field
Create sub-fields id, shooter_id, defender_id, shooterReady, defenderReady

Your mutation should look like this.

UpdateOnlineBattle

update_battles is a mutation that allows us to update a new battle row in our battles table in Hasura.

This would be used to join battles (ergo, setting the defender_id to the player's id) and to update the shooterReady and defenderReady flags.

DeleteBattle

mutation DeleteBattle{
    delete_battles{
        returning{
            id
        }
    }
}

To create this in our Api reference

Click Create New Mutation
Name it DeleteBattle
Select delete_battles as the mutation
Click Confirm Mutation
Create the returning field
Create sub-fields id

Your mutation should look like this.

DeleteBattle

delete_battles is a mutation that allows us to delete a battle row in our battles table in Hasura.

This would be used to delete battles if no one joins after a period of time.

DeleteOldBattles

mutation DeleteOldBattles{
    delete_old_battles{
        returning{
            id
        }
    }
}

To create this in our Api reference

Click Create New Mutation
Name it DeleteOldBattles
Select delete_old_battles as the mutation
Click Confirm Mutation
Create the returning field
Create sub-fields id

Your mutation should look like this.

DeleteOldBattles

old_battles is a view that shows battles that were created over 50 seconds ago and no one joined.

delete_old_battles is a mutation to delete the battles that fall into that view.

This would be used to clean up the database and delete any old battles that exist.

Subscription

For now, we shall create only one subscription. SubscribeToBattle

subscription SubscribeToBattle{
    battles_by_pk{
        id
        shooterReady
        defenderReady
        shooter{
            id
            username
        }
        defender{
            id
            username
        }
        shooter_lastseen
        defender_lastseen
    }
}