Saving multiple fields as array

You’d probably be best to use add_settings_field and add_settings_section…

But in any case, save_testimonials is your validation / save callback function. It is given the data from the form and its job is to check it and then return the validated options. You shouldn’t be touching $_POST or $_REQUEST – that’s the point of the settings api.

save_callback{$array_of_data_from_form){

     //Validate the $array_of_data_from_form 

     $validated=array()//Your settings array after validation

    return $validated;
}`

But it will only recieve data with input name option_testimonials as registered in your register_setting. So your input fields will need names like option_testimonials[testimonial] and option_testimonials.

Best practise dictates that you should prefix your option names (option_testimonials is a bit too generic).

As far tutorials go concerning the settings API you can’t go far wrong with this post.