Unhandled Rejection (TypeError): Cannot read property 'filter' of undefined - json

Question

I am trying to filter search my API data in react.js but I'm getting this error, cannot read property 'filter' of undefined. This is my JSON data link: https://alert-amigo-api.herokuapp.com/products/
Since the JSON data returns an array of objects, I have declared that in the props and used the same. What is the problem?
import FilterResults from 'react-filter-search';
import React, { Component } from "react";
class UserProfile extends Component {
constructor(props) {
super(props);
this.state = {
error: null,
isLoaded: false,
products: [],
value: ''
};
}
componentWillMount() {
fetch('https://jsonplaceholder.typicode.com/users')
.then(response => response.json())
.then(
(result) => {
this.setState({
isLoaded: true,
products: result.products
});
},
// Note: it's important to handle errors here
// instead of a catch() block so that we don't swallow
// exceptions from actual bugs in components.
(error) => {
this.setState({
isLoaded: true,
error
});
}
)
console.log(this.state.products[0]);
}
handleChange = event => {
const { value } = event.target;
this.setState({ value });
};
render() {
const { error, isLoaded, products, value } = this.state;
if (error) {
return <div>Error: {error.message}</div>;
} else if (!isLoaded) {
return <div>Loading...</div>;
} else {
return (
<div className="content-margin">
<input type="text" value={value} onChange={this.handleChange} />
<FilterResults
value={value}
products={products}
renderResults={products => (
<div>
{products.map(el => (
<div>
<span>{el.productName}</span>
</div>
))}
</div>
)}
/>
</div>
);
}
}
}
export default UserProfile;

Answer 1

By testing that exact example, you will notice that the fetch URL does not return products:
fetch('https://jsonplaceholder.typicode.com/users')
The URL should be:
fetch('https://alert-amigo-api.herokuapp.com/products/')
Now result.products does contain an array. I suggest slightly bullet-proofing your code:
(result) => {
this.setState({
isLoaded: true,
products: result.products || [] // <-- add empty array
});
Or, if you prefer, on the render method:
render() {
{ products &&
<FilterResults ... />
}
}