editable-contracts

editable-contracts

Yet another React form state management library, but this time so simple & transparent as if it doesn’t exist.

Editing DTO in React controlled form typically requires:

1. Mapping individual values from DTO to React form components such as inputs, dropdowns, radio buttons, etc..
2. Creating and providing onChange and onBlur handlers to React components to update DTO state
3. Validating DTO before it can be submitted back to the server
4. Subscribing React components on changes in DTO state to update UI

editable-contracts' purpose is to reduce amount of boilerplate code needed to build controlled React forms without compromising typesafety while adding almost zero additional abstractions on top of existing DTO <--> UI mapping chain. Essentially it takes DTO and derives an editor object of the same shape but loaded with all you need for React form state management and validation.

Enough said, example:

interface User {
    id: number;
    name?: string;
    role?: string;
}

const user = observable<User>({
    id: 1,
    name: 'Mark Down'
});

const userEditor = editor(user);

const Form: React.FC = observer(() => (
    <form>
        <label>Name</label>
        <input value={user.name} onChange={userEditor.$.name.onChange} />
        <label>Role</label>
        <input value={user.role} onChange={userEditor.$.role.onChange} />
    </form>
));

Example with validation and Anvil design system (Codesandbox Demo):

interface User {
  id: number;
  name: string;
  age: string;
  email?: string;
  role?: string;
  garage?: string[];
}

const user = observable<User>({
  id: 1,
  name: "Jack",
  age: "20"
});

const userEditor = editor(user, {
  $: {
    name: value => value && value.length >= 15 && "Name is too long",
    age: value => !/^\d*$/.test(value) && "Only digits allowed",
    garage: {
      $: [value => value.includes("Harley") && "Only cars allowed"]
    }
  }
});

const App: React.FC = observer(() => {
  return (
    <Form>
      <Input label="Name" {...inputBinding(user.name, userEditor.$.name)} />
      <Input label="Age" {...inputBinding(user.age, userEditor.$.age)} />
      <Input label="Email" {...inputBinding(user.email, userEditor.$.email)} />
      <Input label="Role" {...inputBinding(user.role, userEditor.$.role)} />
      <Button
        onClick={() => {
          if (!user.garage) {
            user.garage = [];
          }
          user.garage.push("");
        }}
        disabled={user.garage && user.garage.length >= 3}
      >
        Add Car to Garage
      </Button>
      <div>
        {user.garage &&
          user.garage.map((_0, index) => (
            <Input
              key={`car_${index}`}
              label={"Car " + (index + 1)}
              {...inputBinding(
                user.garage![index],
                userEditor.$.garage.$![index]
              )}
            />
          ))}
      </div>
    </Form>
  );
});

Why editable-contracts?

TBD