react / nodejs：从选择下拉列表中接收值以将其发送到数据库

Question

I'm having a select dropdown in my react frontend like this

 <select name="level" value={level} onChange={this.handleChange} className="form-control"> <option>Begineer</option> <option>Intermediate</option> <option>Advanced</option> </select> 

I'm handling this value as req.body in my backend. My handleChange function is simply

 handleChange(event) { const state = this.state; state[event.target.name] = event.target.value; this.setState({ state }); } 

When i submit the form, this value does not gets submitted. I'm also intitializing this value in my constructor function. What can i do in this case?

Answer 1

一定是

  this.setState(state)

Answer 2

first of all you need to ad the value to your options

  <option value="Begineer">Begineer</option>

second of all never mutate the state object directly without set state like this

  state[event.target.name] = event.target.value;

instead

 let objToUpdate = {...state};
objToUpdate[event.target.name]=  event.target.value
this.setState(objToUpdate)

this should solve your issue