多选下拉列表CakePHP 3选择了问题

$selected_country = array(1,3);

$this->Form->input('country', [
    'options' => $source_types,
    'label' => 'Country: ',
    'multiple' => true,
    'class' => ' form-control',
    'selected' => $selected_country,
    'type' => 'select'
]);

If selected country has only one value then it selects the option but if the selected country has more than one value then it doesn't select any value.

If you want to pass more than one value on $selected_country, try it:

echo $this->Form->select('rooms', [
    'multiple' => true,
    // options with values 1 and 3 will be selected as default
    'default' => [1, 3]
]);

Reference: CakePHP Cookbook

For anyone this works echo $this->Form->input('venues._ids', ['options' => $venues, 'class'=>'form-control select4', 'label' => false]); IF you have the database associations set up AND you have it referenced in the controller like so

$event = $this->Events->get($id, [
            'contain' => ['Venues']
        ]);

otherwise adding the 'default' => [1, 2] ids in also works but it has to be first created in the controller and then fed to the view in list form.