This project provides a simple starter template for Dfinity Internet Computer using Next.js framework as frontend.
The Most Recent Updates
- NextJS 13.5
- DFX 0.15
- NodeJS 18.16
Backend
- A simple greeting hello world canister written in Motoko
- ImageBucket canister written in Motoko with create image, delete image and getImageById
Frontend
- A simple React HTML form with name input, sending it to greet canister and showing the returned result
- An Image Upload HTML form with Pick an Image button, upload the image to image canister, loading the image back from the canister and display it using useImageObject React Hook
https://u4gun-5aaaa-aaaah-qabma-cai.raw.ic0.app
Install:
- NodeJS 18.* or higherhttps://nodejs.org/en/download/
- Internet Computer dfx CLIhttps://internetcomputer.org/docs/current/developer-docs/setup/install/
- Visual Studio Code (Recommended Code Editor)https://code.visualstudio.com/Download
- VSCode extension - Motoko (Recommended)https://marketplace.visualstudio.com/items?itemName=dfinity-foundation.vscode-motoko
sh -ci"$(curl -fsSL https://internetcomputer.org/install.sh)"Clone this Git repository:
git clone https://github.com/dappblock/nextjs-ic-starterOpen command terminal: Enter the commands to start dfx local server in background:
cdnextjs-ic-starter
dfx start --backgroundNote: If you run it in MacOS, you may be asked to allow connections from dfx local server.
Enter the commands to install dependencies, deploy canister and run Next.js dev server:
npm install
dfx deploy
npm run devCleanup - stop dfx server running in background:
dfx stopInternet Computer has the concept ofCanisterwhich is a computation unit. This project has 3 canisters:
- hello (backend)
- image (backend)
- hello_assets (frontend)
Canister configurations are stored in dfx.json.
Backend code is inside /backend/ written inMotoko language.Motoko is a type-safe language with modern language features like async/await and actor build-in. It also hasOrthogonal persistencewhich I find very interesting.
Image canister is introduced from release v0.2.0. It makes use of orthogonal persistence through stable variables and provides functions for create, delete and get image. See /backend/service/Image.mo.
Frontend code follows Next.js folder convention with /pages storing page React code, /public storing static files including images. This project uses CSS modules for styling which is stored in /ui/styles. React Components are stored in /ui/components
Entry page code is inside /pages/index.js where the magic starts. With the DFX UI declarations generated code, frontend can use RPC style call to server side actor and its functions without worrying about HTTP request and response parsing.
To generate UI declarations:
dfx generate
It will generate files in src/declarations for each canister. In our case, it is image, hello and hello_assets but we only need the backend canister image and hello UI declarations here.
The next step is to adapt it to work with Next.js. The final adapted code is in ui/declaration/hello/index.js. You can also follow the steps below to update it.
Basically, copy image.did.js and index.js from src/declarations/image/
cp src/declarations/image/image.did.js ui/declarations/image/image.did.js
cp src/declarations/image/index.js ui/declarations/image/index.js
Repeat the same for hello.
cp src/declarations/hello/hello.did.js ui/declarations/hello/hello.did.js
cp src/declarations/hello/index.js ui/declarations/hello/index.js
The next step is to update the canister ID env variable in each canister index.js to use NEXT_PUBLIC prefix so that NextJS can recognize when compiling it.
Open ui/declarations/hello/index.js and look for the line:
export const canisterId = process.env.HELLO_CANISTER_ID;
Update HELLO_CANISTER_ID to NEXT_PUBLIC_HELLO_CANISTER_ID:
export const canisterId = process.env.NEXT_PUBLIC_HELLO_CANISTER_ID
To see the final code, check the original ui/declarations in the Git repo.
The generated UI declarations also support TypeScript if you prefer TypeScript.
We use a service locator pattern through actor-locator.js that will handle the dfx agent host using env var NEXT_PUBLIC_IC_HOST.
Creating hello actor:
import{makeHelloActor}from"../ui/service/actor-adapter"
consthello=makeHelloActor()Calling hello actor:
constgreeting=awaithello.greet(name)The beautiful part is you can invoke the hello actor greet function with async/await style as if they are on the same platform. For details, see React Components GreetingSection.js and ImageSection.js in /ui/components/.
Webpack configuration:
In Next.js, it's located in next.config.js.
By using React Hook with actor UI declaration, it can greatly simplify frontend dev. It encourages component based composable logic. A great example is useImageObject.js React Hook in /ui/hooks. Given an imageId, useImageObject can load the image binary and convert it to a HTML image source object ready for use in.
If you look closer, useImageObject.js depends on image-serivce.js which depends on actor-locator.js. When you open ImageSection.js, you can find how useImageObject is being used to greatly reduce the complexity and the underlying calls with Canister. This is the pattern I used very often in my Content Fly Dapp project.
After marking changes in backend code e.g main.mo in /backend/service/hello, you can deploy it to the local DFX server using:
dfx deploy hellohellois the backend canister name defined in dfx.json.
Next.js developers are familiar with the handy hot code deployed in the Next.js dev environment when making changes in frontend code.
After deploying your backend code as shown above, you can run Next.js local dev servernpm run devand edit your frontend code with all the benefits of hot code deploy.
One thing to note is we use Next.js static code export here for hosting in Internet Computer so we can't use any features of Next.js that require server side NodeJS. Potentially, there might be ways to use Internet Computer canister as backend while deploying Next.js dapp to a hosting like Vercel that supports NodeJS server in the future. Further research is needed on that aspect. However, if you do want to run everything decentralized on blockchain including the frontend, you would want to deploy the exported static code to Internet Computer as well.
In order to simulate the whole Internet Computer experience, you can deploy and run frontend code to local DFX server by running:
dfx start --background
npm run build
dfx deploy hello_assetshello_assetsis the frontend canister defined in dfx.json.
npm run buildbuilds and export Next.js as static code storing in/outfolder which would be picked up bydfx deploy hello_assetsas defined in dfx.json with/outas the source.
When it completes, you can open Chrome and browse to:
http://localhost:8000/?canisterId=[canisterId]
Replace [canisterId] with the hello_assets canister ID which you can find by running:
dfx canister id hello_assetsThere are three key configs following Next.jsEnvironment Variablesconfiguration:
.env.developmentstores configs for use in local dev.
NEXT_PUBLIC_IC_HOST=http://localhost:8000
.env.productionis used when building and exporting static code usingnpm run build
NEXT_PUBLIC_IC_HOST=http://localhost:8000
Notice both files are identical if we want the Next.js dapp to interact with the local dfx server.
NoteNEXT_PUBLICis the prefix used by Next.js to make env vars available to client side code throughbuild time inlining.
.env.icprodis included for deployment to Internet Computer ic network which would be covered below.
The most exciting part is to deploy your Next.js / Internet Computer Dapp to production Internet Computer mainnet blockchain network.
To do that you will need:
- ICP tokens and convert it tocycles
- Cycles wallet
Follow theNetwork Deploymentguide to create a wallet.
Dfinity offersfree cycleto developers.
Now, you can deploy your Next.js Dapp to Internet Computer IC network by adding--network icto the dfx subcommand. We will first update our env var to point to IC network host. Then deploy the backend canister first, export Next.js static code and deploy frontend canisterhello_assets.
cp.env.icprod.env.production
dfx deploy --network icOpen Chrome and go to https://[canisterId].raw.ic0.app/
Replace [canisterId] by the hello_assets canister id in the IC network. You can find it by running:
dfx canister --network ic id hello_assetsCongratulations!! Well Done!! 👏 🚀 🎉
Use Chrome Dev Tools / Console / Network. Check if the dapp uses the right canister id and hostname.
Henry Chan,[email protected] Twitter: @kinwo
Please feel free to raise an issue or submit a pull request.
MIT