React input defaultValue doesn't update with state

Question

I'm trying to create a simple form with react, but facing difficulty having the data properly bind to the defaultValue of the form.

The behavior I'm looking for is this:

1. When I open my page, the Text input field should be filled in with the text of my AwayMessage in my database. That is "Sample Text"
2. Ideally I want to have a placeholder in the Text input field if the AwayMessage in my database has no text.

However, right now, I'm finding that the Text input field is blank every time I refresh the page. (Though what I type into the input does save properly and persist.) I think this is because the input text field's html loads when the AwayMessage is an empty object, but doesn't refresh when the awayMessage loads. Also, I'm unable to specify a default value for the field.

I removed some of the code for clarity (i.e. onToggleChange)

    window.Pages ||= {}

    Pages.AwayMessages = React.createClass

      getInitialState: ->
        App.API.fetchAwayMessage (data) =>
        @setState awayMessage:data.away_message
        {awayMessage: {}}

      onTextChange: (event) ->
        console.log "VALUE", event.target.value

      onSubmit: (e) ->
        window.a = @
        e.preventDefault()
        awayMessage = {}
        awayMessage["master_toggle"]=@refs["master_toggle"].getDOMNode().checked
        console.log "value of text", @refs["text"].getDOMNode().value
        awayMessage["text"]=@refs["text"].getDOMNode().value
        @awayMessage(awayMessage)

      awayMessage: (awayMessage)->
        console.log "I'm saving", awayMessage
        App.API.saveAwayMessage awayMessage, (data) =>
          if data.status == 'ok'
            App.modal.closeModal()
            notificationActions.notify("Away Message saved.")
            @setState awayMessage:awayMessage

      render: ->
        console.log "AWAY_MESSAGE", this.state.awayMessage
        awayMessageText = if this.state.awayMessage then this.state.awayMessage.text else "Placeholder Text"
        `<div className="away-messages">
           <div className="header">
             <h4>Away Messages</h4>
           </div>
           <div className="content">
             <div className="input-group">
               <label for="master_toggle">On?</label>
               <input ref="master_toggle" type="checkbox" onChange={this.onToggleChange} defaultChecked={this.state.awayMessage.master_toggle} />
             </div>
             <div className="input-group">
               <label for="text">Text</label>
               <input ref="text" onChange={this.onTextChange} defaultValue={awayMessageText} />
             </div>
           </div>
           <div className="footer">
             <button className="button2" onClick={this.close}>Close</button>
             <button className="button1" onClick={this.onSubmit}>Save</button>
           </div>
         </div>

my console.log for AwayMessage shows the following:

AWAY_MESSAGE Object {}
AWAY_MESSAGE Object {id: 1, company_id: 1, text: "Sample Text", master_toggle: false}

Answer 1

Another way of fixing this is by changing the key of the input.

<input ref="text" key={this.state.awayMessage ? 'notLoadedYet' : 'loaded'} onChange={this.onTextChange} defaultValue={awayMessageText} />

Update: Since this get upvotes, I will have to say that you should properly have a disabled or readonly prop while the content is loading, so you don't decrease the ux experience.

And yea, it is most likely a hack, but it gets the job done.. ;-)

Answer 2

defaultValue is only for the initial load

If you want to initialize the input then you should use defaultValue, but if you want to use state to change the value then you need to use value. Personally I like to just use defaultValue if I'm just initializing it and then just use refs to get the value when I submit. There's more info on refs and inputs on the react docs, https://facebook.github.io/react/docs/forms.html and https://facebook.github.io/react/docs/working-with-the-browser.html.

Here's how I would rewrite your input:

awayMessageText = if this.state.awayMessage then this.state.awayMessage.text else ''
<input ref="text" onChange={this.onTextChange} placeholder="Placeholder Text" value={@state.awayMessageText} />

Also you don't want to pass placeholder text like you did because that will actually set the value to 'placeholder text'. You do still need to pass a blank value into the input because undefined and nil turns value into defaultValue essentially. https://facebook.github.io/react/tips/controlled-input-null-value.html.

getInitialState can't make api calls

You need to make api calls after getInitialState is run. For your case I would do it in componentDidMount. Follow this example, https://facebook.github.io/react/tips/initial-ajax.html.

I'd also recommend reading up on the component lifecycle with react. https://facebook.github.io/react/docs/component-specs.html.

Rewrite with modifications and loading state

Personally I don't like to do the whole if else then logic in the render and prefer to use 'loading' in my state and render a font awesome spinner before the form loads, http://fortawesome.github.io/Font-Awesome/examples/. Here's a rewrite to show you what I mean. If I messed up the ticks for cjsx, it's because I normally just use coffeescript like this, .

window.Pages ||= {}

Pages.AwayMessages = React.createClass

  getInitialState: ->
    { loading: true, awayMessage: {} }

  componentDidMount: ->
    App.API.fetchAwayMessage (data) =>
      @setState awayMessage:data.away_message, loading: false

  onToggleCheckbox: (event)->
    @state.awayMessage.master_toggle = event.target.checked
    @setState(awayMessage: @state.awayMessage)

  onTextChange: (event) ->
    @state.awayMessage.text = event.target.value
    @setState(awayMessage: @state.awayMessage)

  onSubmit: (e) ->
    # Not sure what this is for. I'd be careful using globals like this
    window.a = @
    @submitAwayMessage(@state.awayMessage)

  submitAwayMessage: (awayMessage)->
    console.log "I'm saving", awayMessage
    App.API.saveAwayMessage awayMessage, (data) =>
      if data.status == 'ok'
        App.modal.closeModal()
        notificationActions.notify("Away Message saved.")
        @setState awayMessage:awayMessage

  render: ->
    if this.state.loading
      `<i className="fa fa-spinner fa-spin"></i>`
    else
    `<div className="away-messages">
       <div className="header">
         <h4>Away Messages</h4>
       </div>
       <div className="content">
         <div className="input-group">
           <label for="master_toggle">On?</label>
           <input type="checkbox" onChange={this.onToggleCheckbox} checked={this.state.awayMessage.master_toggle} />
         </div>
         <div className="input-group">
           <label for="text">Text</label>
           <input ref="text" onChange={this.onTextChange} value={this.state.awayMessage.text} />
         </div>
       </div>
       <div className="footer">
         <button className="button2" onClick={this.close}>Close</button>
         <button className="button1" onClick={this.onSubmit}>Save</button>
       </div>
     </div>

That should about cover it. Now that is one way to go about forms which uses state and value. You can also just use defaultValue instead of value and then use refs to get the values when you submit. If you go that route I would recommend you have an outer shell component (usually referred to as high order components) to fetch the data and then pass it to the form as props.

Overall I'd recommend reading the react docs all the way through and do some tutorials. There's lots of blogs out there and http://www.egghead.io had some good tutorials. I have some stuff on my site as well, http://www.openmindedinnovations.com.

Answer 3

it's extremely simple, make defaultValue and key the same:

<input defaultValue={myVal} key={myVal}/>

This is one of the recommended approaches at https://reactjs.org/blog/2018/06/07/you-probably-dont-need-derived-state.html#recommendation-fully-uncontrolled-component-with-a-key

Answer 4

To force the defaultValue to re-render all you need to do is change the key value of the input itself. here is how you do it.

<input 
type="text" 
key={myDynamicKey} 
defaultValue={myDynamicDefaultValue} 
placeholder="It works"/>

Answer 5

Maybe not the best solution, but I'd make a component like below so I can reuse it everywhere in my code. I wish it was already in react by default.

<MagicInput type="text" binding={[this, 'awayMessage.text']} />

The component may look like:

window.MagicInput = React.createClass

  onChange: (e) ->
    state = @props.binding[0].state
    changeByArray state, @path(), e.target.value
    @props.binding[0].setState state

  path: ->
    @props.binding[1].split('.')
  getValue: ->
    value = @props.binding[0].state
    path = @path()
    i = 0
    while i < path.length
      value = value[path[i]]
      i++
    value

  render: ->
    type = if @props.type then @props.type else 'input'
    parent_state = @props.binding[0]
    `<input
      type={type}
      onChange={this.onChange}
      value={this.getValue()}
    />`

Where change by array is a function accessing hash by a path expressed by an array

changeByArray = (hash, array, newValue, idx) ->
  idx = if _.isUndefined(idx) then 0 else idx
  if idx == array.length - 1
    hash[array[idx]] = newValue
  else
    changeByArray hash[array[idx]], array, newValue, ++idx 

Answer 6

Related issue

Setting defaulValue on control din't not update the state.

Doing reverse works perfectly:

• Set state to default value, and the control UI gets updated correctly as if defaulValue was given.

Code:

let defaultRole = "Owner";

const [role, setRole] = useState(defaultRole);

useEffect(() => {
    setMsg(role);
});

const handleChange = (event) => {
    setRole(event.target.value );
};

// ----

<TextField
    label="Enter Role"
    onChange={handleChange}
    autoFocus
    value={role}
/>

Answer 7

1. Define a state for your default value
2. Surround your input with a div and a key prop
3. Set the key value to the same value as the defaultValue of the input.
4. Call your setDefaultValue defined at the step 1 somewhere to re-render your component

Example:

const [defaultValue, setDefaultValue] = useState(initialValue);

useEffect(() => {
    setDefaultValue(initialValue);
}, false)

return (
    <div key={defaultValue}>
        <input defaultValue={defaultValue} />
    </div>
)

Answer 8

Give value to parameter "placeHolder". For example :-

 <input 
    type="text"
    placeHolder="Search product name."
    style={{border:'1px solid #c5c5c5', padding:font*0.005,cursor:'text'}}
    value={this.state.productSearchText}
    onChange={this.handleChangeProductSearchText}
    />

Answer 9

If you want to render dynamic data in the form value then you have to use:

    setValue("fname", "Bilal");
    setValue("lname", "Khan");
    setValue("address", "Pakistan");

from react hook form. This will dynamically change your data on click or on some event in the form value field.

Answer 10

Use value instead of defaultValue and change the value of the input with the onChange method.