useReducer 打字稿：状态类型

Question

在实现reducer时如何做状态类型？我有属性和功能。

export interface State {
  form: boolean;
  errorForm: boolean;
  projects: ProjectI[];
  project: ProjectI;
  showFormFn(): void;
  getProjectsFn(): void;
  addProjectFn(project: ProjectI): void;
  showErrorFn(): void;
  currentProjectFn(projectId: string): void;
  deleteProjectFn(projectId: string): void;
}

但是我在使用钩子并尝试初始化状态时遇到了问题。正确的实施方式是什么？

Answer 1

这是一种以经典方式实现它的方法：

interface ProjectI {
    id: string;
}

export interface State {
    form: boolean;
    errorForm: boolean;
    projects: ProjectI[];
    project: ProjectI;
    showFormFn(): void;
    getProjectsFn(): void;
    addProjectFn(project: ProjectI): void;
    showErrorFn(): void;
    currentProjectFn(projectId: string): void;
    deleteProjectFn(projectId: string): void;
}

type Actions = { type: 'addProject', payload: ProjectI } | { type: 'setProject', payload: ProjectI } | { type: 'error' }

function reducer(state: State, action: Actions) {
    switch (action.type) {
        case 'addProject':
            return { ...state, projects: state.projects.concat(action.payload) };
        case 'setProject':
            return { ...state, project: action.payload };
        case 'error':
            return { ...state, errorForm: true };
        default:
            return state;
    }
}

TS Playground 显示 typescript 中存在的类型。