Value is undefined while passing data with Context API

user_10001200 0
Viewed 858

I'm trying to pass data with Context API to child components. Value is getting undefined upon fetching it from a component.

Component Hierarchy:

  • passing data to a component MockTable and UsecasePane
  • MainContent -> MockTable
  • MainContent -> AddMock -> TabContent -> UsecasePane

=> MockContext.js

import React, { useState, useEffect, createContext } from "react";
import axios from "axios";

export const MockContext = createContext();

// provider
export const MockProvider = (props) => {
  const [data, setData] = useState([]);
  
   // data fetch and setting the state

  return (
    <MockContext.Provider data={[data, setData]}>
      {props.children}
    </MockContext.Provider>
  );
};
  • Note: I'm getting response from the API.

Now in MainContent, components are encapsulated as follows:

// MainContent.js

import React from "react";
import { MockProvider } from "../MockContext";

const MainContent = () => {
  return (
    <MockProvider>
      <div>
        <CustomerTable />
        <AddMock />
        <MockTable />
      </div>
    </MockProvider>
  );
};

When I try to fetch the data in MockTable or in UseCasePane, value is undefined.

// MockTable.js

import React, { useState, useEffect, useContext } from "react";
import { MockContext } from "./MockContext";

const MockTable = () => {

  const [data, setData] = useContext(MockContext);
  console.log(data);

  // rest of the code

}

Please correct me where I'm going wrong :)

I tried to pass a String as well from the context and fetched in a component like:

return (
    <MockContext.Provider data={"Hello"}>
      {props.children}
    </MockContext.Provider>
  );


// in MockTable.js
const value = useContext(MockContext); ==> undefined
react-context react-hooks reactjs javascript
1 Answers

The correct prop to pass into the Provider is value, not data. (See: Context.Provider)


import React, { useState, useEffect, createContext } from "react";
import axios from "axios";

export const MockContext = createContext();

// provider
export const MockProvider = (props) => {
  const [data, setData] = useState([]);
  const fetchData = async () => {
    const response = await axios
      .get(config.App_URL.getAllRoute, {
        params: {
          customHostName: config.host,
          type: config.type,
        },
      })
      .catch((error) => {
        console.error(`Error in fetching the data ${error}`);
      });
    console.log(response.data);
    setData(response.data);
  };
  useEffect(() => {
    fetchData();
  }, []);

  return (
    <MockContext.Provider value={[data, setData]}>
      {props.children}
    </MockContext.Provider>
  );
};
user_31580990
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