modeladmin example

//First File TestimonialAdmin
class TestimonialAdmin extends ModelAdmin

public function getEditForm($id = null, $fields = null)
    {

        $form = parent::getEditForm($id, $fields);
        $gridField = $form->Fields()->fieldByName($this->sanitiseClassName($this->modelClass));
            if(!sizeof($gridField->getList())){
                $t = new Testimonial();
                $t->write();
            }
        $config = $gridField->getConfig();
        $config->addComponent(new GridFieldSaveBox("Testimonial Saved"));
        $config->addComponent(new GridFieldAddBox("Testimonial","Testimonial Added"));
        $config->addComponent(new GridFieldDeleteAction());


             $gridField->setConfig($config);
             return $form;

    }

//Second file GridFieldSaveBox

<?php

class GridFieldSaveBox implements GridField_ColumnProvider, GridField_ActionProvider
{

    private $successmsg;

    public function __construct($msg=null)
    {
        $this->successmsg = $msg;
    }

    public function augmentColumns($field, &$cols)
    {
        if(!in_array('Save', $cols)) $cols[] = 'Save';
    }

    public function getColumnsHandled($field)
    {
        return array('Save');
    }

    public function getColumnContent($gridfield, $record, $col)
    {
        if($record->canEdit()) {
            $field = GridField_FormAction::create(
                $gridfield,
                "Save",
                "Save",
                'saverecords',
                array(
                    'record' => $record,
                )
            );
            return $field->Field();
        }
    }

    public function getColumnAttributes($field, $record, $col)
    {
        return array('class' => 'col-' . preg_replace('/[^\w]/', '-', $col));
    }

    public function getColumnMetadata($gridfield, $col)
    {
        return array('title' => 'Save');
    }

    public function getActions($gridfield)
    {
        return array('saverecords');
    }

    public function handleAction(GridField $gridfield, $actionName, $arguments, $data)
    {
        if($actionName == 'saverecords') {
                $msg = '';
                $cn = $arguments['record']->ClassName;
                $dos = DataObject::get($cn);
                foreach($dos as $do){
                foreach($data['returns'.$do->ID] as $d => $k)
                    $do->setField($d,$k);
                    $do->write();
                }
            if($this->successmsg){
                $msg = $this->successmsg;
            }
            else {
                $msg = "Object successfully saved.";
            }
            Controller::curr()->getResponse()->setStatusCode(
                200,
                $msg
            );
        }
    }
}