Warning: input is a void element tag and must not have `children` or use `props.dangerouslySetInnerHTML`. Check the render method of null

问题

I am trying to render the errors in the form if the ajax call to the form URL fails. Below is my Admin component:

#app/assets/javascripts/components/admin.js.coffee
@Admin = React.createClass
#  propTypes: ->
#    emailVal: React.PropTypes.string.isRequired

  getInitialState: ->
    edit: false
    errorTexts: []

  handleToggle: (e) ->
    e.preventDefault()
    @setState edit: !@state.edit
    @setState errorTexts: []

  handleDelete: (e) ->
    e.preventDefault()
    # yeah... jQuery doesn't have a $.delete shortcut method
    $.ajax
      method: 'DELETE'
      url: "/admins/#{ @props.admin.id }"
      dataType: 'JSON'
      success: () =>
        @props.handleDeleteAdmin @props.admins

  handleEdit: (e) ->
    e.preventDefault()
    data = email: ReactDOM.findDOMNode(@refs.email).value
    # jQuery doesn't have a $.put shortcut method either
    $.ajax
      method: 'PUT'
      async: false
      url: "/admins/#{ @props.admin.id }"
      dataType: 'JSON'
      data:
        admin: data
      error: (data, status, xhr) =>
        errorTexts = []
        for key, value of data.responseJSON
          errorText = "#{key} #{value.toString()}"
          errorTexts.push errorText
        @replaceState errorTexts: errorTexts
        @setState edit: true
      success: (data, status, xhr) =>
        @setState edit: false
        @props.handleEditAdmin @props.admin, data

  adminRow: ->
    dom.tr null,
      dom.td null, @props.admin.email
      dom.td null,
        dom.a
          className: 'btn btn-default'
          onClick: @handleToggle
          'Edit'
        dom.a
          className: 'btn btn-danger'
          onClick: @handleDelete
          'Delete'

  adminForm: ->
    dom.tr null,
      dom.td null,
        dom.input
          className: 'form-control'
          type: 'text'
          defaultValue: @props.admin.email
          ref: 'email'
          for errorText, index in @state.errorTexts
            React.createElement AdminError, key: index, errorText: errorText
      dom.td null,
        dom.a
          className: 'btn btn-default'
          onClick: @handleEdit
          'Update'
        dom.a
          className: 'btn btn-danger'
          onClick: @handleToggle
          'Cancel'

  render: ->
    if @state.edit
      @adminForm()
    else
      @adminRow()

The corressponding AdminError component is:

#app/assets/javascripts/components/adminerror.js.coffee
@AdminError = React.createClass

  getDefaultProps: ->
    errorText: ""

  render: ->
    dom.div
      className: 'help-block'
      @props.errorText

While debugging I am getting the correct value of @props.errorText as "email is invalid". But it is not getting rendered on the page and I am geeting this warning in console: "Warning: input is a void element tag and must not have children or use props.dangerouslySetInnerHTML. Check the render method of null." Attached is the screenshot of both the error and the page.

I tried changing the AdminError component as follows, but it didn't work:

#app/assets/javascripts/components/adminerror.js.coffee
@AdminError = React.createClass

  getDefaultProps: ->
    errorText: ""

  render: ->
    dom.div
      className: 'help-block'
      dangerouslySetInnerHTML: __html: marked(@props.errorText.toString(), {saitize: true})

When I set a debug point at the line returning dangerouslySetInnerHTML, I correctly get the value of @props.errorText as "email is invalid" and value of marked(@props.errorText.toString()) as "

email is invalid

".. but still the help-block for error is not rendered at all.

UPDATE: Made the following changes in the AdminError component

app/assets/javascripts/components/adminerror.js.coffee

@AdminError = React.createClass

  getDefaultProps: ->
#    errorText: ""
    errorTexts: []

  render: ->
    for errorText in @props.errorTexts
      dom.div
        className: 'help-block'
        errorText

and in the Admin component, made the following changes to the adminform method:

if(@state.errorTexts.length>0)
            dangerouslySetInnerHTML: {
              __html: ReactDOMServer.renderToString(
  #              for errorText, index in @state.errorTexts
                React.createElement AdminError, errorTexts: @state.errorTexts
              )
            }

not getting the warning anymore, but instead getting the following error:

Uncaught Invariant Violation: ReactCompositeComponent.render(): A valid ReactComponent must be returned. You may have returned undefined, an array or some other invalid object.

回答1:

Warning: input is a void element tag and must not have children ...

A dom.input may not have child elements.

But this code is trying to render error messages as children of a dom.input:

  dom.td null,
    dom.input
      className: 'form-control'
      type: 'text'
      defaultValue: @props.admin.email
      ref: 'email'
      # These are being rendered as children of the input: 
      for errorText, index in @state.errorTexts
        React.createElement AdminError, key: index, errorText: errorText

Can you render those error messages somewhere else? For example, as siblings of the input:

  dom.td null,
    dom.input
      className: 'form-control'
      type: 'text'
      defaultValue: @props.admin.email
      ref: 'email'
    for errorText, index in @state.errorTexts
      React.createElement AdminError, key: index, errorText: errorText

来源：https://stackoverflow.com/questions/35956483/warning-input-is-a-void-element-tag-and-must-not-have-children-or-use-props