limit the number of entries and restart after break in the for loop

Question

I have a model and ready-made data in a table. In this model, I added a new field and made a connection with another table.

And in order not to manually fill in these fields for each record, I want to create a migration that will automatically fill in this field for all records.

Relationship table has two fields: post_id and author_id.

I am trying to do like this:

$posts = Posts::find()->all();

foreach ($posts as $index => $post) {
    for($i = 0, $j = 0; $i < $index; $j++, $i++) {
        if ($j >= 4) {
          break;
        }
        $item = new PostAuthor();
        $item->setAttribute('post_id', $posts->id);
        $item->setAttribute('author_id', $j + 1);
        $item->save();
    }
}

Or:

$posts = Posts::find()->all();

foreach ($posts as $index => $post) {
    for($i = 0; $i < $index && $i < 4; $i++) {
        $item = new PostAuthor();
        $item->setAttribute('post_id', $posts->id);
        $item->setAttribute('author_id', $i + 1);
        $item->save();
    }
}

But I get the same, only when j reaches 4, the cycle does not start again, and it adds everything else from 1 to 4:

Is it possible to make the loop start over for the post IDs I'm circling in the screenshot?

In idea my table should look like this

Answer 1

$posts = Posts::find()->all();
$authors = [1,2,3,4]; //ids of the authors
$i = 1;
foreach($posts as $post){
  $postAuthors = array_slice($authors, 0, $i);
  $post->authors()->sync($postAuthors); //I assume your relation is belongsToMany(), otherwise you can foreach $postAuthors to create PostAuthor
  $i++;
  //you can use $i+=rand(1,4) instead to add more randomness
  if($i>4){
    $i=0; //settings to 0 will produce each 5 post to not have authors. If you set to 1 all posts will have author
  }
}

For each post we take N authors, sync relation then reset counter