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VisualizaçõesPassing selected value of Dropdown into API in react
Hi I need to populate list in dropdown when the page gets loaded so I put the same in componentDidMount().
componentDidMount() {
axios.get(`http://localhost:8080/country_code`).then((res) => {
const countryData = res.data;
this.setState({ countryData });
});
}
This data needs to be part of dropdownlist.
<select id="dropdown">
{this.state.countryData.map((countryData) => (
<option key={countryData} value={countryData}>
{countryData}
</option>
))}
</select>
list is getting displayed like below.
Myrequirement is if user select any value in dropdown list that value should be passed in API as parameter to backend.
what changes I need to do in Select or Option. I know how to write call API in reactjs using axios.that I will manage.
My updated code is below.
<select id="dropdown" onChange={this.downLoadFile(e)}>
{this.state.countryData.map((countryData) => (
<option key={countryData} value={countryData}>
{countryData}
</option>
))}
</select>
downLoadFile(e) {
this.setState({ selectValue: e.target.value });
alert(selectValue);
}
this.state = {
countryData: [],
selectValue: '',
};
this.handleChange = this.handleChange.bind(this);
this.downLoadFile = this.downLoadFile.bind(this);
}
Its not working. what wrong I am doing?
Edit1:-
downLoadFile(e) {
e.preventDefault();
this.setState({ selectValue: e.target.value });
alert(selectValue);
}
<select id="dropdown" onChange={this.downLoadFile}>
{this.state.countryData.map((countryData) => (
<option key={countryData} value={countryData}>
{countryData}
</option>
))}
</select>
it is giving below error.
in constrtor I have below code.
this.state = {
selectValue: ''
};
2 Respostas
Responde à pergunta0
You should pass function to onChange event. Like:
<select id="dropdown" onChange={(e) => {this.downLoadFile(e)}}>
or
<select id="dropdown" onChange={this.downLoadFile}>
The way you do is just pass the return value of this.downLoadFile
Update:
alert(selectValue)
must be
alert(this.state.selectValue);
0
You should fetch API after the update of the selected state.
downLoadFile(e) {
this.setState({ selectValue: e.target.value }, () => {
fetchSomeApi(this.state.selectValue).then((res) => {
updateSomewhere(res);
}).catch((error) => console.error(error));
});
alert(this.state.selectValue); // < --- changes this line
}
this.setState has second parameter as callback. So you could use that for after state update event.
Also, you can update the function call.
onChange={this.downloadFile)