[英]Why isn't child component re-rendered even though parent state is updated using hooks
[英]I can't figure out why my component does not rendered with the updated state. Even though, the state is updated and reflected in the database
因此,我正在開發一個簡單的CRUD note應用程序。 當我的組件進入編輯模式並且完成編輯時,我遇到了這個問題。 PUT請求成功更新了數據庫中的內容,並且編輯模式組件將返回到正常注釋。 以下是相關代碼:
constructor(props) {
super(props);
this.state = {
notes: [],
id: null,
title: "",
content: "",
toEdit: null
}
this.handleTitleChange = this.handleTitleChange.bind(this);
this.handleContentChange = this.handleContentChange.bind(this);
this.handleSubmit = this.handleSubmit.bind(this);
this.deleteNote = this.deleteNote.bind(this);
this.handleEditSubmit = this.handleEditSubmit.bind(this);
}
handleContentChange = (event) => {
this.setState({ content: event.target.value});
}
這是更新功能:
// Handle new content edit
handleEditSubmit = (noteId) => {
console.log(noteId)
axios.put('http://localhost:3000/notes/' + noteId,
{
content: this.state.content
})
.then(res => {
// Rerender the editNote into a normal note.
this.setState({
toEdit: null,
}, () => {console.log(this.state.content, this.state.toEdit)})
console.log(res);
})
.catch(err => {
console.log(err);
this.setState({ toEdit: null })
})
}
最后,當toEdit為null時,呈現普通筆記組件,而當toEdit === index時,呈現編輯模式組件:
{this.state.notes.map((output, index) => {
if (this.state.toEdit === index) {
return (
<div key={index} className="note">
<div className="title-container"><h4>{output.title}</h4></div>
<textarea
className="textarea"
type="text"
name="edit-content"
defaultValue={output.content}
onChange={this.handleContentChange}
/>
<Button bsStyle="danger" type="button" onClick={this.handleCancel} >Cancel</Button>
<Button bsStyle="primary" type="button" onClick={this.handleEditSubmit.bind(this, output.id)} >Done</Button>
</div>
)
} else {
return (
<div key={index} className="note">
<div className="title-container"><h4>{output.title}</h4></div>
<p>{output.content}</p>
<Button bsStyle="danger" onClick={this.deleteNote.bind(this, index, output.id)}>Delete</Button>
<Button bsStyle="primary" onClick={this.edit.bind(this, index)} >Edit</Button>
</div>
)
}
}
在PUT請求之后和重新呈現之后,編輯后的文本將不會顯示。 必須刷新頁面以獲取更新的注釋。 看看gif: https : //giphy.com/gifs/dn15rkILhjMyvVl8CX/fullscreen
您沒有更改notes []中的任何內容,因為您正在使用{this.state.notes.map((output, index) => {
來呈現注釋。應該在axios完成后更新notes []實體。像這樣的東西
handleEditSubmit = (noteId) => {
console.log(noteId)
axios.put('http://localhost:3000/notes/' + noteId,
{
content: this.state.content
})
.then(res => {
// Rerender the editNote into a normal note.
this.setState({
toEdit: null,
notes:res.notes // this is changed part
}, () => {console.log(this.state.content, this.state.toEdit)})
console.log(res);
})
.catch(err => {
console.log(err);
this.setState({ toEdit: null })
})
}
注意: notes:res.notes // this is changed part
更改
因此,此更改之后,this.state.notes將具有新的更新,您可以輕松地進行綁定。
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