React JS: Get Context Data After getting success on API Call

问题

I am stuck at getting context data.

I have a context and a component which uses its data.

I need to get the updated data of context's variable on API call success in my component.

so How can I do that ? Here what I have tried.

context.js

import React, { useState, createContext,useEffect } from 'react';
import {getData} from './actionMethods';

const NewContext = createContext();

function newContextProvider(props) {

 const [dataValue, setData] = useState([])

    useEffect(() => {
        const fetchMyData = async () => {
            const dataValue  = await getData(); // this is an API call

            setData(dataValue)
        };

        fetchMyData();
    }, []);

     
     return (
        <NewContext.Provider
            value={{
                state: {
                    dataValue
                },
                actions: {
                    
                }
            }}
        >
            {props.children}
        </NewContext.Provider>
    );
}


const newContextConsumer = newContext.Consumer;

export { newContextProvider, newContextConsumer, newGridContext };

myComponent.js

import React, { useState, useContext } from 'react'

import context from './context'


import deleteAPI from './actionMethods'

function myComponent(props) {

const id= 10

const {state,actions} = useContext(context)
  
  deleteAPI(id).then(res => {
    if (res){
      // what should I write here to get the updated Data from the context which will call an API to get the updated data.    
    }
  })
  
  
}

Any help would be great.

Thank You.

回答1:

As a generic example, one option is to fetch the data from the server when the app loads in the front-end. From there you can send requests to modify the server data and at the same time update your local version. Something like:

Fetch data and save it to the local store: [{id: 0, name: 'first'},{id: 1, name: 'second'}]
Modify the data sending a request to the server. For example deleting an item. id: 0
Once the server responds confirming the operation was successful you can modify that data in the local store. [{id: 1, name: 'second'}]

You can handle the data using a Redux store or a React Context. For example, using a Context:

export const ItemsContext = createContext([]);

export const ItemsContextProvider = props => {
    const [items, setItems] = useState([]);

    const deleteItem = id => {
        deleteItemsAxios(id).then(() => {
            setItems(items => items.filter(item => item.id !== id));
        });
    };

    useEffect(() => {
        const fetchItems = async () => {
            const items_fetched = await fetchItemsAxios();

            if (items_fetched) {
                setItems(items_fetched);
            } else {
                // Something went wrong
            }
        };

        fetchItems();
    }, []);

    return (
        <ItemsContext.Provider
            value={{
                items,
                deleteItem
            }}
        >
            {props.children}
        </ItemsContext.Provider>
    );
};

We define a Component that will manage the data fetch. The data items are inside a state. When the Component mounts we fetch the items and save them in the state. If we want to delete an item we first call the corresponding fetch function. Once it finishes, if it was successful, we update the state and remove that item. We use React Context to pass the items data, as well as the deleteItem function, to any component that needs them.

Let me know if you need more explanation.

来源：https://stackoverflow.com/questions/59372275/react-js-get-context-data-after-getting-success-on-api-call

标签

reactjs

react-hooks

react-context