Hi Reader's,
Welcome to FindNerd,today we are going to discuss to default checked the checkboxes in CakePHP 3
If we want to set checkbox in our cakephp application for showing list of a product in checkbox then firstly we have to find a list of products from our database.

for example

suppose there is a table name is "product" and we want to find all products then our query will like below
 

<?php

  //prodLists is a varibale
  $prodLists= $this->product->find('list', array(
    'fields' => array('id')
  ));

?>

Now let set product for checked

$selectedProducts= array(1,2,3);

It represents what all Products you want to be checked. In above example 1,2,3 is id's.
Now we have to set all these values to the checkbox.
you can see below code:

<?php

echo $this->Form->input('User.product', array(
    'label' => 'Productlist',
    'type' => 'select',
    'multiple' => 'checkbox',
    'options' => $prodlists,//you can set the variable as shown in above example 
    'selected' => $selectedProducts
  ));

?>

you can write in the list of the id's as defined in above example,which will automatically display checkbox as selected with id's 1,2,3.