Editing and un-completing your to-dos

In the last section, you learned how to check items off your to-do list. When going over the requirements, there was an option:

As a user, I want to mark un-complete items that are incomplete.

The above requirement changed the scope considerably. Before that requirement, you could delete a completed item from the list. However, once a user wants to see historical items, edit them, or mark them as incomplete, you need to track them forever.

But, of course, that's the better thing to do. That will make your product better, even if it's more work. Creating a product isn't always easy. So let's jump in and get into the nitty-gritty!

Un-completing items

This turns out to be pretty straightforward. There are two things you will need to do to get this working. The first is to show the user those completed items. The second is to reverse the "complete" function to mark them as done.

Showing the items is easy. Duplicate the code for displaying the items, but instead of filtering out the things that are not done, filter out the ones that are done. It looks like this.

<ul>
  {todos
    .filter(({ done }) => done)
    .map((todo) => (
      <TodoListItem key={todo.id} onComplete={onComplete} {...todo} />
    ))}
</ul>

The function onComplete still works here because of a tricky line of code you entered earlier: done: !todos[i].done. That line doesn't set done to false at all times. Instead, it flips the bit from true to false or vice versa. That allows you to call the same function and have it change the to-do from done to not done.

Great job! You can now mark items as not complete. To add more distinction between the two lists, you can add a header to mark the items that have been finished:

<h2>Complete</h2>

Put that right before your second ul to note the items below have been completed.

All Complete!

Congrats! Now your users can mark items not complete if they accidentally tap the button. They can correct their mistakes which is always an important function. The user can fix their errors.

Right?

All their mistakes...

Hmm, what if they mistyped a to-do in the first place? Do the users want to edit a to-do?

Just have them complete it and enter it again!

No? They didn't like that response?

Fine.

Time to add editing.

Editing a to-do

Alright, well, this starts getting tricky. Editing a to-do changes the interaction paradigm a user has with their to-dos. There are also multiple ways to do this, so feel free to diverge a little and tackle it another way.

A user will most likely want to view and complete a to-do. Editing is a less common interaction, and it should not be the primary mode of interaction. You might want to make every to-do list item just an input field so the user can always edit it, but that's not the best idea. If you do that, the user will accidentally trigger editing items when they don't want to.

Instead, a better option is to break up the modes. One mode for viewing and completing (the primary way) and then a button flips the user into edit mode, where all they can do is edit the to-do.

With this approach, you can break the code into two distinct modes, viewing and editing. Then, the components can match the mode with an "Edit this to-do list item" and "view this to-do list item" component. The list itself doesn't need to know what mode any individual row is in; it just needs to know when one of them changes.

Let's work from what you have and move down. Update the component TodoListItem so that it tracks the mode. It is either in edit mode or not, and the user can change that. It sounds like a new state! Add it:

const [isEditMode, setEditMode] = useState(false)

The user will not start in edit mode, which is most common. So what happens with that state? The user toggles the state, and the app shows different functionality based on the view.

That's a lot to fit into a single component, and those are two different behaviors. When you come to points like this... make more components! Create two new components, one for each mode:

const ViewTodoListItem = () => null

const EditTodoListItem = () => null

You'll fill out the contents of those later. But you can now finish the stub of TodoListItem by calling those:

return <li>{isEditMode ? <EditTodoListItem {...todo} /> : <ViewTodoListItem {...todo} />}</li>

If isEditMode is true, return the edit mode. Otherwise, return the view mode. Now, TodoListItem used to be view-only mode, so you mostly have that done. So jump there and finish up that component.

View mode of a list item

Copying the old code from TodoListItem gives you a component that looks like this.

type TodoListItemProps = {
  onChange: () => void
} & Todo

const ViewTodoListItem = ({ text, done, onChange }: TodoListItemProps) => (
  <li>
    <input type="checkbox" checked={done} onChange={(e) => onChange()} />
    <span>{text}</span>
  </li>
)

After adding that, change the props to be named ViewTodoProps. You'll come back to onChange; it can just stay there for now. The last thing is a new addition.

The list item will show this component when not in edit mode. How does the user enter edit mode? A user interaction will change the state. To make it easy and obvious, you'll add a button.

<button>Edit</button>

Toss that button after the span element. Then, when the user clicks it, you need to trigger a callback to tell the parent to update its mode.

type ViewTodoProps = {
  onComplete: () => void
  onEdit: () => void // Add this line
} & Todo

// Lower, update this line
;<button onClick={onEdit}>Edit</button>

Back in TodoListItem, it needs to pass in the callback that will change the mode.

<ViewTodoListItem onEdit={() => setEditMode((e) => !e)} {...todo} />

The above code uses the function setter to set isEditMode according to the previous value. When you press the edit button, it will hide the ViewTodoListItem and show... nothing! Time to work on editing.

Edit mode of a list item

The edit mode is simple, a text box with a button to save. Very similar to adding an item. You also need to handle passing that data back up to the list so it can set the state of the to-do. Just like marking an item as complete goes up, so needs changing the text of an item.

Editing a to-do will look like this:

type EditTodoProps = {} & Todo

const EditTodoListItem = ({ ...todo }: EditTodoProps) => {
  const [text, setText] = useState(todo.text)
  return (
    <>
      <input type="text" value={text} onChange={(e) => setText(e.target.value)} />
      <button>Save</button>
    </>
  )
}

There should not be anything too surprising about this. The most interesting line is the useState line. Instead of setting the default state to '', which you've done before, you set it to the text of the to-do item. This means the text field will start with that text instead of being blank. When the input changes, you update the state. Lastly, a save button that does nothing yet.

When the user clicks save, it needs to call a function letting the parent know the user wants to save this to-do. The parent is no longer the list; it is the TodoListItem. So that component needs to call a callback to let the TodoList itself know something changed.

Phew.

Luckily, you can structure our code so passing these through is pretty painless. You do that by structuring the functions to have the same function signature.

Working backward, when a user clicks "save" to save an edited to-do, you need to call a function saying that to-do had the text changed, and here is the new text. This could be done by just passing the text to a function, but if you pass the entire Todo object, it will make things a lot easier. You'll see why in a moment.

So, add a new callback for saving:

type EditTodoProps = {
  onUpdate: (todo: Todo) => void // Added
} & Todo

const EditTodoListItem = ({ onUpdate, ...todo }: EditTodoProps) => {
  const [text, setText] = useState(todo.text)

  // This line is new
  const update = () => onUpdate({ ...todo, text })

  return (
    <>
      <input type="text" value={text} onChange={(e) => setText(e.target.value)} />
      /* This line is updated */
      <button onClick={update}>Save</button>
    </>
  )
}

The onUpdate function requires the entire Todo passed in. You call that with update in your component that passes back the Todo passed to you with the updated text. Now you need to update the parent TodoListItem.

type TodoListItemProps = {
  onEdit: (todo: Todo) => void
} & Todo

// Below, in the JSX update this line
;<EditTodoListItem onUpdate={onEdit} {...todo} />

You add a new property, onEdit, which will tell the TodoList when a to-do has been edited. Then you pass that function to EditTodoListItem.

Because the function signature is the same, you don't need to invoke it with:

onUpdate={(todo) => onEdit(todo)}

The above is redundant and not necessary. You can just pass it through because the function is called with the same parameters. Easy!

Now backing up once again to the TodoList you can write onEdit.

const onEdit = (todo: Todo) => {
  setTodos((todos) => {
    const i = todos.findIndex(({ id }) => todo.id === id)
    todos[i] = todo
    return [...todos]
  })
}

The above code is a little simpler than onComplete because instead of changing the Todo to flip the done value, you just trust that the to-do passed in is the one that should be set. Then, the code looks up that index and overrides the entire to-do.

Since you're overriding the Todo, this means the done value is also set.

It means that this function can do the same thing as onComplete but easier. So you can actually remove onComplete and update that functionality.

<ViewTodoListItem
  onComplete={() => onEdit({ ...todo, done: !todo.done })}
  onEdit={() => setEditMode((e) => !e)}
  {...todo}
/>

Instead of calling a unique onComplete method now, when the user taps onComplete, set the value of done to be the opposite of what was there before. Then call onEdit, which is your function above, setting the Todo. The same function handles both completing a to-do and editing one!

And now the user can do both of those actions! Once a user enters edit mode, you'll notice that they don't get out when they click save. You can update the TodoListItem code to kick them out when they save:

const onUpdate = (todo: Todo) => {
  setEditMode(false)
  onEdit(todo)
}

// Later
;<EditTodoListItem onUpdate={onUpdate} {...todo} />

Finishing with style

The app is getting to the point where manually editing CSS is a pain. It's in a different file, and the DOM doesn't have classes or IDs. While you can add those, there are better ways to handle CSS in React. For example, instead of adding CSS in a file, a shortcut is to add inline CSS right in the JSX.

To start, that <h2>Complete</h2> you added earlier can be a little nicer.

<h2 style={{ textAlign: 'center', fontSize: 14 }}>Complete</h2>

React inline styles are an object, not a string. The CSS properties are camel-cased, and some can be numbers instead of strings where it makes sense. Above, the font-size is 14 pixels.

Since you already have some CSS for the following, go and open App.css and update:

ul li div {
  padding: 0.5rem;
  display: flex;
  align-items: flex-start;
}

ul li span {
  margin-left: 0.5rem;
  flex-grow: 1;
}

And your app will look nicer. Not great, but nicer. It's about time to really up the ante in making an app.