# Create Custom Objects
Make sure you have everything you need before proceeding:
- You understand the concepts of Protobuf.
- You have completed the introductory CosmJS tutorial.
- Go and npm are installed.
- You have finished the checkers blockchain exercise. If not, you can follow that tutorial here, or just clone and checkout the relevant branch (opens new window) that contains the final version.
With your checkers application ready for use, it is a good time to prepare client elements that eventually allow you to create a GUI and/or server-side scripts. Here, you will apply what you have learned about creating your own custom CosmJS interfaces.
Before you can get into working on your application directly, you need to make sure CosmJS understands your checkers module and knows how to interact with it. This generally means you need create the Protobuf objects and clients in TypeScript and create extensions that facilitate the use of them.
# Compile Protobuf
You will have to create a
client folder that will contain all these new elements. If you want to keep the Go parts of your checkers project separate from the TypeScript parts, you can use another repository for the client. To keep a link between the two repositories, add the client parts as a submodule to your Go parts:
Replace the path with your own repository. In effect, this creates a new
client folder. This
client folder makes it possible for you to easily update another repository with content generated out of your Go code.
Create a folder named
scripts in your project root. This is where you will launch the Protobuf compilation. In the
scripts folder install modules for the Protobuf-to-TypeScript compiler:
Create the folder structure to receive the compiled files:
Check what Cosmos version you are using:
This may return:
Download the required files from your
You should now have your TypeScript files.
In order to easily repeat these steps in the future, you can add them to your existing
Makefile with slight modifications:
Then whenever you want to re-run them:
You have created the basic Protobuf objects (opens new window) that will assist you with communicating with the blockchain.
# Prepare integration
At this point, you have the
generated files in your
client folder. If you have made this
client folder as a Git submodule, then you can work directly in it and do not need to go back to the checkers Cosmos SDK:
Also, if you use Docker and did not go through the trouble of building the Docker image for the checkers Cosmos SDK, you can use the
Install the Protobuf.js package in your client project:
At a later stage, you will add checkers as an extension to Stargate, but you can define your checkers extension immediately. The
canPlay query could make use of better types for player and position. Start by declaring them in
Your checkers extension will need to use the CosmJS Stargate package. Install it:
Now you can declare the checkers extension in
Do not forget a setup function, as this is expected by Stargate:
You may have to add these imports by hand:
Now create your
# Integration tests
It is possible to already run some integration tests against a running checkers blockchain.
Install packages to run tests.
Describe how to connect to the running blockchain in a
.env file in your project root:
Alternatively, use whichever address connects to the RPC port of the checkers blockchain. If your chain runs in a Docker container, you may need to pass your actual IP address.
This information will be picked up by the
dotenv package. Now let TypeScript know about this in an
Also add your
tconfig.json as you see fit:
Add the line that describes how the tests are run:
# First tests
Because the intention is to run these tests against a running chain they cannot expect too much, such as how many games have been created so far. Still, it is possible to at least test that the connection is made and queries pass through.
And create one for stored games:
Note the forced import of
import _ from "../../environment", to actively inform on the
string type (as opposed to
string | undefined) and avoid any compilation error.
Launch your checkers chain, for instance from the checkers folder with:
Now if you run the tests:
This should return:
To summarize, this section has explored:
- The need to prepare the elements that will eventually allow you to create a GUI and/or server-side scripts for your checkers application.
- How to create the necessary Protobuf objects and clients in Typescript, the extensions that facilitate the use of these clients, so that CosmJS will understand and be able to interact with your checkers module.