How do I delete a list item that has been given a unique id when created, in React + Firebase?



I am creating a Todo list using React and Firebase. So far, I have already created the AddToDo functionality, however, now I am having trouble with the delete functionality. I believe this is where my problem lies. For example, when I try and click the delete icon that I set up, I get an error:

Unhandled Runtime Error
TypeError: Cannot read properties of undefined (reading 'id')

This is the code if it helps. AddLink.js

import { useState, useEffect } from "react";
import classes from "./addlink.module.css";

import firebase from "firebase/app";
import initFirebase from "../../config";
import "firebase/firestore";

import Todo from "../Todo/Todo";

import { v4 as uuidv4 } from "uuid";

initFirebase();
const db = firebase.firestore();

function AddLink(props) {
  const [todos, setTodos] = useState([]);
  const [input, setInput] = useState("");

  useEffect(() => {
    db.collection("links")
      .orderBy("timestamp", "desc")
      .onSnapshot((snapshot) => {
        // this gives back an array
        setTodos(
          snapshot.docs.map((doc) => ({
            id: doc.id,
            todo: doc.data().todo,
          }))
        );
      });
  }, []);

  const addTodo = (event) => {
    event.preventDefault();

    console.log("clicked");

    db.collection("links").add({
      id: uuidv4(),
      todo: input,
      timestamp: firebase.firestore.FieldValue.serverTimestamp(),
    });
    setInput("");
  };

  return (
    <div className={classes.addlink}>
      <form>
        <div className={classes.adminlink}>
          <input
            type="text"
            value={input}
            onChange={(event) => setInput(event.target.value)}
          />
          <button
            className={classes.adminbutton}
            type="submit"
            onClick={addTodo}
          >
            Add new link
          </button>
        </div>
      </form>
      {todos.map((todo, id) => (
        <Todo value={todo} key={id} />
      ))}
      {/* {modalIsOpen && (
          <Modal onCancel={closeModalHandler} onConfirm={closeModalHandler} />
        )}
        {modalIsOpen && <Backdrop onCancel={closeModalHandler} />} */}
    </div>
  );
}

export default AddLink;

And Todo.js

import React from "react";
import { AiOutlinePicture } from "react-icons/ai";
import { AiOutlineStar } from "react-icons/ai";
import { GoGraph } from "react-icons/go";
import DeleteForeverIcon from "@material-ui/icons/DeleteForever";

import classes from "./todo.module.css";

import firebase from "firebase/app";
import initFirebase from "../../config";
import "firebase/firestore";

initFirebase();
const db = firebase.firestore();

function Todo(props) {
  const deleteHandler = () => {
    db.collection("todos").doc(props.todo.id).delete();
  };

  return (
    <li className={classes.adminsection}>
      <div className={classes.linkCards}>
        <h3>{props.text}</h3>
        <p>This is a new link</p>
        <div>
          <AiOutlinePicture />
          <AiOutlineStar />
          <GoGraph />
          <DeleteForeverIcon onClick={deleteHandler} />
        </div>
      </div>
    </li>
  );
}

export default Todo;

Any help would be greatly appreciated.

Answer

 const deleteHandler = () => {
    db.collection("todos").doc(props.todo.id).delete();
  };

You should replace props.todo.id with props.value.id.

 const deleteHandler = () => {
    db.collection("todos").doc(props.value.id).delete();
  };

Alternatively you can change:

<Todo value={todo} key={id} />

To

<Todo todo={todo} key={id} />

The key you use to access props.value should be the same as the one declared in the jsx template. Using proptypes can help you avoid those mistakes.



Source: stackoverflow