nextjs is a nodejs library that is a framework for building modern web apps from backend and frontend. Here I will share my experience of learning nextjs by coding a todo list demo project. Here is my project repository

create a nextjs project

We may create a floder for our project:

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mkdir nextjs-demo-todo-list
cd todoList-demo-by-nextjs
npx create-next-app@latest .

install dependencies

For our simple demo project, we need to install prisma, that is a open-source ORM for nodejs.

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npm install prisma

and we just use prisma to generate a sqlite database file:

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npx prisma init --datasouce-provider sqlite

create the ORM model and migrate the db schema

in prisma/schema.prisma file, we may updated as below:

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model Todo {
id String @id @default(uuid())
title String
complete Boolean
createAt DateTime @default(now())
updateAt DateTime @updatedAt
}

run the migrate command:

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npx prisma migrate dev --name init

we may see the prisma/migrations floder, and see the sql file.

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-- CreateTable
CREATE TABLE "Todo" (
"id" TEXT NOT NULL PRIMARY KEY,
"title" TEXT NOT NULL,
"complete" BOOLEAN NOT NULL,
"createAt" DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
"updateAt" DATETIME NOT NULL
);

init the db seed data

we may refer to this prisma official tutorial to generate db seed data.

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touch prisma/seed.ts
# using ts-node to run seed.ts file:
npm i -D ts-node

seed.ts:

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import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient();

async function main() {
// generate the first todo data:
await prisma.todo.create({
data: {
title: "Hello World",
complete: false,
},
});
}

main()
.then(async () => {
await prisma.$disconnect();
})
.catch(async (e) => {
console.error(e);
await prisma.$disconnect();
process.exit(1);
});

in our project’s script, we may adding the config in tsconfig.json file:

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"ts-node": {
"compilerOptions": {
"module": "CommonJS"
}
}

and then run the seed script:

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npx ts-node ./prisma/seed.ts

startup the prisma UI page

the prisma UI page is a web page that can help us to manage the db schema and data. we may run the command. it’s very easy to use.

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npx prisma studio

it can be accessed by http://localhost:5555

create the db instance file

we may create a src/db.ts file to init the db instance:
the boliplate code is from this prisma official tutorial :

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import { PrismaClient } from "@prisma/client";

const prismaClientSingleton = () => {
return new PrismaClient({ log: ["query"] });
};

declare global {
var prisma: undefined | ReturnType<typeof prismaClientSingleton>;
}

export const prisma = globalThis.prisma ?? prismaClientSingleton();

if (process.env.NODE_ENV !== "production") globalThis.prisma = prisma;

update the frontend pages

for the homepage, we may update the src/page.tsx file:

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import { prisma } from "@/db";
import Link from "next/link";
import TodoItem from "./components/TodoItem";
import { redirect } from "next/navigation";

const getTodos = () => prisma.todo.findMany();

// "use server" field might be the nextjs way to handle the server side logic.
const toggleItem = async (id: string, complete: boolean) => {
"use server";
await prisma.todo.update({
where: {
id,
},
data: {
complete,
},
});
};

const deleteItem = async (id: string) => {
"use server";
await prisma.todo.delete({
where: {
id,
},
});
// here refresh the page again, we may see that the item deleted.
redirect("/");
};

const Home = async () => {
// fetching the data from the db:
const todos = await getTodos();

return (
<>
<header className="flex justify-between items-center mb-4">
<h1 className="text-2xl">Todo List</h1>
<Link
href="/new"
className="border border-slate-300 text-slate-300 px-2 py-1 rounded hover:bg-slate-700 focus-within:bg-slate-700 ouline-none"
>
New
</Link>
</header>
<ul className="pl-4">
{todos.map(({ id, complete, title }) => (
<TodoItem
key={id}
id={id}
title={title}
complete={complete}
toggleItem={toggleItem}
deleteItem={deleteItem}
/>
))}
</ul>
</>
);
};

export default Home;

nextjs rounter

as above code, we may see that nextjs provide the Link component to handle the rounter logic:

when we clik the Link, just like the <a/> label, just to the new page:

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import Link from "next/link";

<Link href="/new">New</Link>;

we may code the filesrc/new/page.tsx file:

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import { redirect } from "next/navigation";
import Link from "next/link";
import { prisma } from "@/db";

const createTodo = async (data: FormData) => {
"use server";

const title = data.get("title")?.valueOf();
if (typeof title !== "string" || title.length === 0)
throw new Error("Invalid title");

await prisma?.todo.create({
data: {
title,
complete: false,
},
});
redirect("/");
};

const Page = () => {
return (
<>
<header className="flex justify-between items-center mb-4">
<h1 className="text-2xl">New</h1>
</header>
<form action={createTodo} className="flex gap-2 flex-col">
<input
type="text"
name="title"
className="border border-slate-300 bg-transparent rounded px-2 py-1 outline-none focus-within:border-slate-100"
/>
<div className="flex gap-1 justify-end">
<Link
href=".."
className="border border-slate-300 text-slate-300 px-2 py-1 rounded hover:bg-slate-700 focus-within:bg-slate-700 ouline-none"
>
Cancel
</Link>
<button
type="submit"
className="border border-slate-300 text-slate-300 px-2 py-1 rounded hover:bg-slate-700 focus-within:bg-slate-700 ouline-none"
>
Create
</button>
</div>
</form>
</>
);
};

export default Page;

TodoItem component

for the TodoItem component, we may update the src/components/TodoItem.tsx file:

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"use client";
// TodoItem function is the server side function, so we must mark "use client" field for this component
type TodoItemProps = {
id: string,
title: string,
complete: boolean,
toggleItem: (id: string, complete: boolean) => void,
deleteItem: (id: string) => void,
};

const TodoItem = ({
id,
title,
complete,
toggleItem,
deleteItem,
}: TodoItemProps) => {
return (
<li className="flex gap-1 items-center">
{/* here using the call back function toggleItem to pass the id and value: */}
<input
id={id}
type="checkbox"
className="cursor-pointer peer"
defaultChecked={complete}
onChange={(e) => toggleItem(id, e.target.checked)}
/>
<label htmlFor={id} className="peer-checked:line-through">
{title}
</label>
<div
className="cursor-pointer rounded-full"
onClick={() => deleteItem(id)}
>

</div>
</li>
);
};

export default TodoItem;