Update React page in class-based component without using useState.
P粉739886290
2023-08-03 21:16:09
<p>I'm using React's class-based component to display all the tokens first. Then I want to display two texts with spanid at the same time, regardless of the order, using the previous and next buttons to re-render the page. There will be n*(n-1) possibilities for re-rendering the page. This is because the first text with a spanid will be paired with the second text with another spanid, up to the n-1th token with a spanid. For n pieces of text with spanid, the page can be re-rendered n*(n-1) times using the previous/next buttons. Since I'm writing code using React's class-based components, I'm not sure how to handle this using useState and props like I would in a functional setup. Any help on this issue is greatly appreciated. </p>
<pre class="brush:php;toolbar:false;">import React from 'react';
import './App.css';
const record = [
{ "tid": 1, "token_text": "Canis Familiaris", "spanid": 1, "label": "Name" },
{ "tid": 2, "token_text": "is" },
{ "tid": 3, "token_text": "the" },
{ "tid": 4, "token_text": "scientific name", "spanid": 2, "label": "name type" },
{ "tid": 5, "token_text": "of" },
{ "tid": 6, "token_text": "dog", "spanid": 3, "label": "species" },
{ "tid": 7, "token_text": "." }
];
class Relation extends React.Component {
const input_tokens = record;
var cntr = 200;
input_tokens.forEach(tk => {
const span = tk['spanid'];
if (!tk['spanid']) {
tokens_to_render.push(
<div key= {`id${cntr}`} >
<div id = {`label${cntr}`} className='no-label' key={tk.tid}>--</div>
<div key={cntr} id = {`span${cntr}`} index={tk['spanid']} >
{tk['token_text']}
</div>
</div>
);
} else {
tokens_to_render.push(
<div key = {`id${cntr}`} >
<div id = {`label${cntr}`} className='label' key={tk.tid} >{tk['label']}</div>
<div
key={cntr} id = {`span${cntr}`}
index={tk['spanid']}
>
{tk['token_text']}
</div>
</div>
);
};
cntr = cntr 1;
});
return (
<div key="outer" >
<div key="id" className="control-box">
{tokens_to_render}
</div>
</div>
)
}
}
export default Relation;</pre>
<p><br /></p>
Translation: Hooks like useState can only be used in function components. To use state in a class component:
For example: