想要在特定条件下显示标签

Question

我想在用户名已经存在时显示标签。我需要申请什么条件..这是我的代码。

handleCheck = () => {
this.props.form.validateFields((err, values) => {
this.props.checkUser(values,this.props.companyId);
});
this.setState({checkFlag:true});
};
<Col span={12} >
<FormItem>
{getFieldDecorator('UserName', {
initialValue: "",
rules: [{
required: true, message: 'Please Input your UserName!',
}],
})(                                
<Input placeholder="UserName" onChange={this.handleCheck} />              
)}
</FormItem>
</Col> 
{(here condition)?
<label for="test" style={{"color":"red","paddingLeft":"54%","fontSize":"13px"}}>Username already exists</label>:''
}

Answer 1

我假设这个函数this.props.checkUser返回真或假。

将句柄检查功能更改为

handleCheck = () => {
this.props.form.validateFields((err, values) => {
let isUserExist = this.props.checkUser(values,this.props.companyId);
this.setState({checkFlag:isUserExist});
});
};

JSX 更改

{this.checkFlag && 
<label for="test" style="color:red;paddingLeft:54%;fontSize:13px">Username already exists</label>}