temporeest/examples/todo-mvc-mem/README copy.md

# Aphrodite Browser Starter

This provides a local-first in browser example project that uses `Aphrodite`.<br/>
See also -- `Aphrodite` in an [interactive reactive notebook](https://observablehq.com/@tantaman/aphrodite-chinook) (observablehq).

**[Launch the app!](https://aphrodite-examples.pages.dev/todo-mvc/)**

# Code Overview

## Schema

The schema that defines the data model is [here](https://github.com/tantaman/aphrodite-browser-starter/blob/main/src/domain.aphro) (reproduced below)

```typescript
engine: sqlite
db: todomvc

Todo as Node {
  id: ID<Todo>
  listId: ID<TodoList>
  text: NaturalLanguage
  created: Timestamp
  modified: Timestamp
  completed: Timestamp | null
} & Mutations {
  create as Create {
    text
    listId
  }

  setComplete as Update {
    completed: Timestamp | null
  }

  changeText as Update {
    text
  }

  delete as Delete {}
}

TodoList as Node {
  id: ID<TodoList>
  filter: Enumeration<all | active | completed>
  editing: ID<Todo> | null
} & OutboundEdges {
  todos: Edge<Todo.listId>
} & Mutations {
  create as Create {}

  filter as Update {
    filter
  }

  edit as Update {
    editing
  }
}
```

## Live Queries

The UI is updated via live queries. Whenever a modification is made to a model through a mutator, that update is reflected back into the UI.

Live queries are [here](https://github.com/tantaman/aphrodite-browser-starter/blob/main/src/App.tsx#L202-L214).

```typescript
const [activeTodos, completeTodos, allTodos] = unwraps(
  useQuery(UpdateType.ANY, () => list.queryTodos().whereCompleted(P.equals(null)), []),
  useQuery(UpdateType.ANY, () => list.queryTodos().whereCompleted(P.notEqual(null)), []),
  useQuery(UpdateType.CREATE_OR_DELETE, () => list.queryTodos(), []),
);
```

## Mutators

Changes to the data model are expressed using changesets. I.e., you collect all the changes you'd like to make and then commit them in one shot -- ensuring minimal notifications of changes and that your state is always consistent.

You can read more about the original idea behind changesets here -- https://tantaman.com/2021-12-16-Missing-Mutation-Primitives.html

Some examples [here](https://github.com/tantaman/aphrodite-browser-starter/blob/main/src/App.tsx#L161-L179)

```typescript
const clearCompleted = () =>
  commit(
    list.ctx,
    completeTodos.map(t => TodoMutations.delete(t, {}).toChangeset()),
  );
const startEditing = (todo: Todo) => TodoListMutations.edit(list, { editing: todo.id }).save();
const saveTodo = (todo: Todo, text: string) => {
  commit(
    list.ctx,
    TodoMutations.changeText(todo, { text: text }).toChangeset(),
    TodoListMutations.edit(list, { editing: null }).toChangeset(),
  );
};
const toggleAll = () => {
  if (remaining === 0) {
    // uncomplete all
    commit(
      list.ctx,
      completeTodos.map(t => TodoMutations.setComplete(t, { completed: null }).toChangeset()),
    );
  } else {
    // complete all
    commit(
      list.ctx,
      activeTodos.map(t => TodoMutations.setComplete(t, { completed: Date.now() }).toChangeset()),
    );
  }
};
```

# Getting The Code

Either open in [GitPod](https://gitpod.io/#git@github.com:tantaman/aphrodite-browser-starter.git) or follow the steps below --

First, clone this repository

```bash
git clone git@github.com:tantaman/aphrodite-browser-starter.git
```

Next, cd to `aphrodite-browser-starter` and install dependencies.

```bash
cd aphrodite-browser-starter
npm install
```

The command to build and run the "demo app" are:

```bash
npm run serve
```

If you change the schema and want to re-generate the generated code, run

```bash
npm run aphro
```

This "demo app" is an implementation of [TodoMVC](https://todomvc.com/) using `Aphrodite` & `React` --