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React context returns promise

I have a todo app. Im trying to use context api(first time). I have add, delete and get functions in context. I can use add and delete but cant return the get response to state. It returns promise if i log; context. Im using async await. I tried almost everything i know but cant solve it. Where is my fault ?
Thank you.
task-context.js
import React, { useReducer } from "react";
import TaskContext from "./task-actions";
import { TaskReducer, ADD_TASK, GET_TASKS, REMOVE_TASK } from "./reducers";
const GlobalState = (props) => {
const [tasks, dispatch] = useReducer(TaskReducer, { tasks: [] });
const addTask = (task) => {
dispatch({ type: ADD_TASK, data: task });
};
const removeTask = (taskId) => {
dispatch({ type: REMOVE_TASK, data: taskId });
};
const getTasks = () => {
dispatch({ type: GET_TASKS });
};
return (
<TaskContext.Provider
value={{
tasks: tasks,
getTasks: getTasks,
addTask: addTask,
removeTask: removeTask,
}}
>
{props.children}
</TaskContext.Provider>
);
};
export default GlobalState;
reducers.js
import taskService from "../Services/tasks-service";
export const ADD_TASK = "ADD_TASK";
export const GET_TASKS = "GET_TASKS";
export const REMOVE_TASK = "REMOVE_TASK";
const addTask = async (data, state) => {
console.log("Adding : " + data.title);
try {
let task = {
title: data.title,
description: data.description,
comment: data.comment,
progress: data.status
};
const res = await taskService.addNewTask(task);
console.log(res);
if (res) {
getTasks();
}
} catch (err) {
console.log(err);
}
return;
};
const getTasks = async () => {
let response = {}
try {
const res = await taskService.loadTasks();
response = res.data
} catch (err) {
console.log(err);
}
return { tasks: response }
};
const removeTask = async (data) => {
try {
await taskService.deleteTask(data.id);
} catch (err) {
console.log(err);
}
};
export const TaskReducer = (state, action) => {
switch (action.type) {
case ADD_TASK:
return addTask(action.data);
case GET_TASKS:
console.log(getTasks());
return getTasks();
case REMOVE_TASK:
return removeTask(action.data);
default:
return state;
}
};
task-actions.js
import React from "react";
export default React.createContext({
addTask: (data) => {},
removeTask: (data) => {},
getTasks: () => {}
});

To start with, you are getting promises returned because you are explicitly returning promises: return addTask(action.data). All your actions are returning promises into the reducer.
A reducer should be a pure function, meaning that it does not have any side effects (call code outside its own scope), or contain any async functionality, and it should return the same data given the same inputs every single time. You've essentially got the workflow back to front.
There's a lot to unpick here so I'm going to provide pseudocode rather than try and refactor the entire service, which you will have a more complete understanding of. Starting with the reducer:
export const TaskReducer = (state, action) => {
switch (action.type) {
case ADD_TASK:
return [...state, action.data];
case GET_TASKS:
return action.data;
case REMOVE_TASK:
return state.filter(task => task.id !== action.data.id);
default:
return state;
}
};
This reducer describes how the state is updated after each action is complete. All it should know how to do is update the state object/array it is in charge of. When it comes to fetching data, calling the reducer should be the very last thing you have to do.
Now on to the actions. The add action is a problem because its not actually returning any data. On top of that, it calls getTasks when really all it ought to do is return one added task (which should be getting returned from await taskService.addNewTask). I would expect that res.data is actually a task object, in which case:
export const addTask = async (data) => {
try {
const task = {
title: data.title,
description: data.description,
comment: data.comment,
progress: data.status
};
const res = await taskService.addNewTask(task);
return res.data;
} catch (err) {
return err;
}
};
Similarly for getTasks, I'm going to assume that await taskService.loadTasks returns an array of task objects. In which case, we can simplify this somewhat:
export const getTasks = async () => {
try {
const res = await taskService.loadTasks();
return res.data;
} catch (err) {
return err;
}
};
Your removeTask action is essentially fine, although you will want to return errors instead of just logging them.
Notice we're now exporting these actions. That is so we can now call them from within GlobalState. We're running into issues with name collision so I've just underscored the imported actions for demo purposes. In reality, it might be better to move all the functionality we did in the last step into your taskService, and import that straight into GlobalState instead. Since that's implementation specific I'll leave it up to you.
import {
TaskReducer,
ADD_TASK,
GET_TASKS,
REMOVE_TASK,
addTask as _addTask,
getTasks as _getTasks,
removeTask as _removeTask,
} from "./reducers";
const GlobalState = (props) => {
const [tasks, dispatch] = useReducer(TaskReducer, { tasks: [] });
const addTask = async (task) => {
const added = await _addTask();
if (added instanceof Error) {
// handle error within the application
return;
};
dispatch({ type: ADD_TASK, data: added });
};
const removeTask = async (taskId) => {
const removed = await _removeTask(taskId);
if (removed instanceof Error) {
// handle error within the application
return;
};
dispatch({ type: REMOVE_TASK, data: taskId });
};
const getTasks = async () => {
const tracks = await _getTracks();
if (tracks instanceof Error) {
// handle error within the application
return;
};
dispatch({ type: GET_TASKS, data: tracks });
};
...
}
Hopefully now you can see how the workflow is supposed to progress. First we call for data from our backend or other API, then we handle the response within the application (for instance, dispatching other actions to notify about errors or side effects of the new data) and then finally dispatch the new data into our state.
As stated at the beginning, what I've provided is essentially pseudocode, so don't expect it to work out of the box.

How to mock multiple promise .then in react hooks and check for state set in one .then

The question could be seen as similar to this one but is not working really the same way as that one is checking for a function to be called while im looking for a state to change.
The code i have is this one (headers and body are not really important in this case):
const useGetToken = () => {
const [token, setToken] = useState();
const [loading, setLoading] = useState(false);
const [error, setError] = useState();
const fetchToken = useCallback(() => {
setLoading(true);
fetch('http://localhost.something', {
headers,
body,
})
.then((response) => {
response.json();
})
.then((response) => {
setToken(response.access_token);
})
.catch((e) => {
setError(e);
})
.finally(() => {
setLoading(false);
});
}, []);
return { fetchToken, token, error, loading };
};
what I am trying to find is a way to test that the output I have is the correct one in case of success and in case of error.
Seems like I can mock until the first .then but then i dont know how to mock the second one.
import { renderHook, act } from '#testing-library/react-hooks';
describe('useGetToken', () => {
it('should fetch and return a token', () => {
global.fetch = jest.fn().mockImplementation(() =>
Promise.resolve({
json: () => ({ access_token: 'aToken' }),
}),
);
const { result } = renderHook(() => useGetToken());
// also how to check for the fetchToken function to equal to itself i dont know how to do
// or maybe i can check if it is just a function
expect(result.current).toEqual({ token: 'aToken', loading: false, error: false });
});
});

managed a way to fix it changing with async await and the correct act.
also changed the double .then in the file to this
.then((response) => {
const parsedResponse = response.json();
setToken(parsedResponse.access_token);
})
cause i didnt need two
import { renderHook, act } from '#testing-library/react-hooks';
import useGetToken from '../useGetVfsToken';
describe('useGetToken', () => {
it('should fetch when fetchToken is called', async () => {
global.fetch = jest.fn().mockImplementation(() =>
Promise.resolve({
json: () => ({ access_token: 'aToken123' }),
}),
);
const { result } = renderHook(() => useGetToken());
expect(window.fetch).not.toHaveBeenCalled();
await act(async () => {
result.current.fetchToken();
});
expect(window.fetch).toHaveBeenCalledTimes(1);
expect(result.current.token).toEqual('aToken123');
expect(result.current.loading).toEqual(false);
expect(result.current.error).toBeUndefined();
});
it('should have an error', async () => {
const error = 'an error text';
global.fetch = jest.fn().mockImplementation(() => Promise.reject(error));
const { result } = renderHook(() => useGetToken());
await act(async () => {
result.current.fetchToken();
});
expect(result.current.error).toEqual(error);
expect(result.current.loading).toEqual(false);
});
});

Testing a fetch.catch in custom hook

I've got this custom hook:
import React from 'react';
import { useMessageError } from 'components/Message/UseMessage';
export interface Country {
code: string;
name: string;
}
export default function useCountry(): Array<Country> {
const [countries, setCountries] = React.useState<Country[]>([]);
const { showErrorMessage } = useMessageError();
React.useEffect(() => {
fetch('/api/countries', {
method: 'GET',
})
.then(data => data.json())
.then(function(data) {
// ..
})
.catch(() => showErrorMessage());
}, []);
return countries;
}
I want to test catching an error if there will be invalid response. With that, error message should appear thanks to showErrorMessage(). And I've got this test:
const showErrorMessage = jest.fn();
jest.mock('components/Message/UseMessage', () => ({
useMessageError: () => ({
showErrorMessage: showErrorMessage,
}),
}));
import useCountry from 'components/Country/useCountry';
import { renderHook } from '#testing-library/react-hooks';
import { enableFetchMocks } from 'jest-fetch-mock';
enableFetchMocks();
describe('The useCountry hook', () => {
it('should show error message', async () => {
jest.spyOn(global, 'fetch').mockImplementation(() =>
Promise.resolve({
json: () => Promise.reject(),
} as Response),
);
const { result, waitForNextUpdate } = renderHook(() => useCountry());
await waitForNextUpdate();
expect(fetch).toHaveBeenCalled();
expect(showErrorMessage).toHaveBeenCalled();
expect(result.current).toEqual([]);
});
});
But with that, I'm getting an error:
Timeout - Async callback was not invoked within the 5000ms timeout specified by jest.setTimeout.Timeout - Async callback was not invoked within the 5000ms timeout specified by jest.setTimeout.Error
What I'm doing wrong in here? I assume it is somehow related with await waitForNextUpdate();, but I really don't know for sure and how to manage with it.

waitForNextUpdate() waits for next update but your hook does not trigger it since it only calls showErrorMessage(). Take a look at this sandbox
As a straightforward solution something that triggers an update can be added:
React.useEffect(() => {
fetch('/api/countries', {
method: 'GET',
})
.then(data => data.json())
.then(function(data) {
// ..
})
.catch(() => {
showErrorMessage();
// trigger update in any suitable way, for example:
setCountries([]);
});
}, []);
But it may be better to refactor it in some way. For example, you could use a separate hook and state for errors:
export default function useCountry(): Array<Country> {
const [countries, setCountries] = React.useState<Country[]>([]);
const [error, setError] = React.useState(null);
const { showErrorMessage } = useMessageError();
React.useEffect(() => {
fetch('/api/countries', {
method: 'GET',
})
.then(data => data.json())
.then(function(data) {
// ..
})
.catch(() => setError(true));
}, []);
React.useEffect(() => {
if (error) {
showErrorMessage()
}
}, [error]);
return countries;
}

How to call callback function after dispatch action Redux

I use React Redux and I create a function to login, but I need to get a callback return after successfull login and redirect user to a page.
I try to passing function as parameter but not working.
How can I get the return after dispatch action?
Login fun
export const login = (request,cb) => {
return dispatch => {
let url = "/api/user/login";
axios({
method: "post",
url: url,
data: request,
config: { headers: { "Content-Type": "multipart/form-data" } }
})
.then(response => {
let authState = {
isLoggedIn: true,
user: response.data
};
cb();
window.localStorage["authState"] = JSON.stringify(authState);
return dispatch({
type: "USER_LOGIN_FULFILLED",
payload: { userAuthData: response.data }
});
})
.catch(err => {
return dispatch({
type: "USER_LOGIN_REJECTED",
payload: err
});
});
};
};
submiting
handleLogin(e) {
this.setState({ showLoader: true });
e.preventDefault();
const request = new Object();
if (this.validator.allValid()) {
request.email = this.state.email;
request.password = this.state.password;
this.props.login(request, () => {
//get callbach here
this.props.history.push('/my-space/my_views');
})
this.setState({ showLoader: false });
} else {
this.setState({ showLoader: false });
this.validator.showMessages();
this.forceUpdate();
}
}
const mapStateToProps = state => {
return {
authState: state
};
};
const mapDispatchToProps = dispatch => {
return {
login: request => dispatch(login(request))
};
};
export default connect(mapStateToProps, mapDispatchToProps)(LoginForm);

The cb is missing in your connect(...)
Here is the fix
handleLogin(e) {
this.setState({ showLoader: true });
e.preventDefault();
const request = new Object();
if (this.validator.allValid()) {
request.email = this.state.email;
request.password = this.state.password;
this.props.login(request, () => {
//get callbach here
this.props.history.push('/my-space/my_views');
})
this.setState({ showLoader: false });
} else {
this.setState({ showLoader: false });
this.validator.showMessages();
this.forceUpdate();
}
}
const mapStateToProps = state => {
return {
authState: state
};
};
const mapDispatchToProps = dispatch => {
return {
login: (request, cb) => dispatch(login(request, cb))
};
};
export default connect(mapStateToProps, mapDispatchToProps)(LoginForm);
Hope it helps:)

If you are using redux-thunk, you can return a Promise from your async action.
The function called by the thunk middleware can return a value,
that is passed on as the return value of the dispatch method.
In this case, we return a promise to wait for.
This is not required by thunk middleware, but it is convenient for us.
But I prefer use useEffect or componentDidUpdate for this purpose:
componentDidUpdate(){
if(this.props.authState.isLoggedIn){
this.props.history.push('/my-space/my_views');
}
}

I recommend using the Redux Cool package if you need actions with callback capability.
Instalation
npm install redux-cool
Usage
import {actionsCreator} from "redux-cool"
const my_callback = () => {
console.log("Hello, I am callback!!!")
}
const callbackable_action = actionsCreator.CALLBACKABLE.EXAMPLE(1, 2, 3, my_callback)
console.log(callbackable_action)
// {
// type: "CALLBACKABLE/EXAMPLE",
// args: [1, 2, 3],
// cb: f() my_callback,
// _index: 1
// }
callbackable_action.cb()
// "Hello, I am callback!!!"
When we try to generate an action object, we can pass the callback function as the last argument. actionsCreator will check and if the last argument is a function, it will be considered as a callback function.
See Actions Creator for more details

react-redux/redux dispatch returns a promise. you can do this if you want to return a value or identify if the request is success/error after being dispatched
Action example
export const fetchSomething = () => async (dispatch) => {
try {
const response = await fetchFromApi();
dispatch({
type: ACTION_TYPE,
payload: response.value
});
return Promise.resolve(response.value);
} catch (error) {
return Promise.reject(error);
}
}
Usage
const foo = async data => {
const response = new Promise((resolve, reject) => {
dispatch(fetchSomething())
.then(v => resolve(v))
.catch(err => reject(err))
});
await response
.then((v) => navigateToSomewhere("/", { replace: true }))
.catch(err => console.log(err));
};
this post is old, but hopefully it will help
Package.json
"react-redux": "^8.0.2"
"#reduxjs/toolkit": "^1.8.5"

Dispatching an action in a debounced function using redux-thunk

I have the following debounced function that gets called every time a user inputs into the username field. It is working as expected.
export const uniqueUsernameCheck = _.debounce(({ username }) => {
axios.post(`${API_URL}/signup/usernamecheck`, { username })
.then((res) => {
console.log('Is unique?', res.data.status);
})
.catch((error) => {
console.log(error);
});
}, 500);
However using redux-thunk I am trying to modify the function so that I can dispatch actions within my function. This is what I have:
export const uniqueUsernameCheck = _.debounce(({ username }) => {
console.log('I can see this');
return (dispatch) => {
console.log('But not this');
dispatch({ type: USERNAME_CHECK });
axios.post(`${API_URL}/signup/usernamecheck`, { username })
.then((res) => {
dispatch(authError(res.data.error));
})
.catch((error) => {
console.log(error);
});
};
}, 500);
The problem lies in that the above code no longer fires off my post request like the initial function did and nothing ever gets dispatched. I know I'm doing something wrong but can't figure out what.
EDIT:
This is how I've set up my store
const store = createStore(reducers, {}, applyMiddleware(ReduxThunk));

Take a look at this:
http://codepen.io/anon/pen/egeOyJ
const userService = _.debounce(username => {
setTimeout(
()=>{
console.log('userService called after debounce. username:', username)
}
,1000)
}, 500)
const uniqueUsernameCheck = (username) => (dispatch) => {
console.log('I can see this')
userService(username)
}
console.log('begin')
const reducers = (action) => {console.log(action)}
const store = Redux.createStore(
reducers,
{},
Redux.applyMiddleware(ReduxThunk.default))
store.dispatch(uniqueUsernameCheck('rafael'))
store.dispatch(uniqueUsernameCheck('rafael'))
store.dispatch(uniqueUsernameCheck('rafael'))