如何从API而不是本地json文件将数据加载到React State

Question

因此，作为我项目的一部分，我试图修改React Pdf Highlighter的样板，以接受来自flask api的Pdf高亮显示，而不是本地文件(该示例带有本地/json导入(。。

我试着和console.log核实了一下，获取不是问题所在，但我觉得这个赛季的"testHighlights"状态不是应该的。<lt；App.js>gt

// @flow
/* eslint import/no-webpack-loader-syntax: 0 */
import React, { Component } from "react";
import PDFWorker from "worker-loader!pdfjs-dist/lib/pdf.worker";
import {
PdfLoader,
PdfHighlighter,
Tip,
Highlight,
Popup,
AreaHighlight,
setPdfWorker
} from "react-pdf-highlighter";

import Spinner from "./Spinner";
import Sidebar from "./Sidebar";
import testHighlights from "./test-highlights";
import type {
T_Highlight,
T_NewHighlight
} from "react-pdf-highlighter/src/types";
import "./style/App.css";

setPdfWorker(PDFWorker);
type Props = {};
type State = {
url: string,
highlights: Array<T_Highlight>
};

const getNextId = () => String(Math.random()).slice(2);
const parseIdFromHash = () =>
document.location.hash.slice("#highlight-".length);
const resetHash = () => {
document.location.hash = "";
};
const HighlightPopup = ({ comment }) =>
comment.text ? (
<div className="Highlight__popup">
{comment.emoji} {comment.text}
</div>
) : null;
const PRIMARY_PDF_URL = "https://arxiv.org/pdf/1708.08021.pdf";
const SECONDARY_PDF_URL = "https://arxiv.org/pdf/1604.02480.pdf";
const searchParams = new URLSearchParams(document.location.search);
const initialUrl = searchParams.get("url") || PRIMARY_PDF_URL;
class App extends Component<Props, State> {



state = {
url: initialUrl,
highlights: testHighlights[initialUrl]
? [...testHighlights[initialUrl]]
: []
};
state: State;
resetHighlights = () => {
this.setState({
highlights: []
});
};
toggleDocument = () => {
const newUrl =
this.state.url === PRIMARY_PDF_URL ? SECONDARY_PDF_URL : PRIMARY_PDF_URL;
this.setState({
url: newUrl,
highlights: testHighlights[newUrl] ? [...testHighlights[newUrl]] : []
});
};
scrollViewerTo = (highlight: any) => {};
scrollToHighlightFromHash = () => {
const highlight = this.getHighlightById(parseIdFromHash());
if (highlight) {
this.scrollViewerTo(highlight);
}
};
componentDidMount() {
window.addEventListener(
"hashchange",
this.scrollToHighlightFromHash,
false
);
}
getHighlightById(id: string) {
const { highlights } = this.state;
return highlights.find(highlight => highlight.id === id);
}
addHighlight(highlight: T_NewHighlight) {
const { highlights } = this.state;
console.log("Saving highlight", highlight);
this.setState({
highlights: [{ ...highlight, id: getNextId() }, ...highlights]
});
}
updateHighlight(highlightId: string, position: Object, content: Object) {
console.log("Updating highlight", highlightId, position, content);
this.setState({
highlights: this.state.highlights.map(h => {
const {
id,
position: originalPosition,
content: originalContent,
...rest
} = h;
return id === highlightId
? {
id,
position: { ...originalPosition, ...position },
content: { ...originalContent, ...content },
...rest
}
: h;
})
});
}
render() {
const { url, highlights } = this.state;
return (
<div className="App" style={{ display: "flex", height: "100vh" }}>
<Sidebar
highlights={highlights}
resetHighlights={this.resetHighlights}
toggleDocument={this.toggleDocument}
/>
<div
style={{
height: "100vh",
width: "75vw",
position: "relative"
}}
>
<PdfLoader url={url} beforeLoad={<Spinner />}>
{pdfDocument => (
<PdfHighlighter
pdfDocument={pdfDocument}
enableAreaSelection={event => event.altKey}
onScrollChange={resetHash}
// pdfScaleValue="page-width"
scrollRef={scrollTo => {
this.scrollViewerTo = scrollTo;
this.scrollToHighlightFromHash();
}}
onSelectionFinished={(
position,
content,
hideTipAndSelection,
transformSelection
) => (
<Tip
onOpen={transformSelection}
onConfirm={comment => {
this.addHighlight({ content, position, comment });
hideTipAndSelection();
}}
/>
)}
highlightTransform={(
highlight,
index,
setTip,
hideTip,
viewportToScaled,
screenshot,
isScrolledTo
) => {
const isTextHighlight = !Boolean(
highlight.content && highlight.content.image
);
const component = isTextHighlight ? (
<Highlight
isScrolledTo={isScrolledTo}
position={highlight.position}
comment={highlight.comment}
/>
) : (
<AreaHighlight
highlight={highlight}
onChange={boundingRect => {
this.updateHighlight(
highlight.id,
{ boundingRect: viewportToScaled(boundingRect) },
{ image: screenshot(boundingRect) }
);
}}
/>
);
return (
<Popup
popupContent={<HighlightPopup {...highlight} />}
onMouseOver={popupContent =>
setTip(highlight, highlight => popupContent)
}
onMouseOut={hideTip}
key={index}
children={component}
/>
);
}}
highlights={highlights}
/>
)}
</PdfLoader>
</div>
</div>
);
}
}
export default App;

<lt测试亮点.js>gt；

const testHighlights =async () => {
const res= await fetch('http://127.0.0.1:5000/jsonapi')
const data =await res.json()
console.log(data)
this.state.testHighlights = data
return testHighlights;
}
export default testHighlights; 

Answer 1

您不能像这样分配状态

this.state.testHighlights = data

您必须使用this.setState函数才能完成

this.setState({ testHighlights: data });

这就是为什么你的testHighlights状态不是你期望的