Adminhtml JSON Response Body

Copypublic function visibleProductsAction()
{
    $this->getResponse()->setBody(
        $this->getLayout()->createBlock('module/adminhtml_block_type')->toHtml()
    );
}

Copy$block = $this->getLayout()->createBlock('adminhtml/template')
    ->setTemplate('system/autocomplete.phtml')
    ->assign('items', $items);

$this->getResponse()->setBody($block->toHtml());

Copyclass Mage_Adminhtml_JsonController extends Mage_Adminhtml_Controller_Action
{
    /**
     * Return JSON-encoded array of country regions
     *
     * @return string
     */
    public function countryRegionAction()
    {
        $arrRes = array();

        $countryId = $this->getRequest()->getParam('parent');
        $arrRegions = Mage::getResourceModel('directory/region_collection')
            ->addCountryFilter($countryId)
            ->load()
            ->toOptionArray();

        if (!empty($arrRegions)) {
            foreach ($arrRegions as $region) {
                $arrRes[] = $region;
            }
        }

        $this->getResponse()->setBody(Mage::helper('core')->jsonEncode($arrRes));
    }

    /**
     * Check is allowed access to action
     *
     * @return bool
     */
    protected function _isAllowed()
    {
        return true;
    }
}

Copypublic function validateAction()
{
    $response       = new Varien_Object();
    $response->setError(0);
    // ...
    if ($errors !== true) {
        foreach ($errors as $error) {
            $this->_getSession()->addError($error);
        }
        $response->setError(1);
    }
    // ...
    $response->setError(1);
    $this->_getSession()->addError(
        Mage::helper('adminhtml')->__('Customer with the same email already exists.')
    );
    // ...
    if ($response->getError()) {
        $this->_initLayoutMessages('adminhtml/session');
        $response->setMessage($this->getLayout()->getMessagesBlock()->getGroupedHtml());
    }

    $this->getResponse()->setBody($response->toJson());
 }

Copy/**
 * @todo add validation for fields
 */
function submitAndReloadArea(area, url) {
    if($(area)) {
        var fields = $(area).select('input', 'select', 'textarea');
        var data = Form.serializeElements(fields, true);
        url = url + (url.match(new RegExp('\\?')) ? '&isAjax=true' : '?isAjax=true');
        new Ajax.Request(url, {
            parameters: $H(data),
            loaderArea: area,
            onSuccess: function(transport) {
                try {
                    if (transport.responseText.isJSON()) {
                        var response = transport.responseText.evalJSON();
                        if (response.error) {
                            alert(response.message);
                        }
                        if(response.ajaxExpired && response.ajaxRedirect) {
                            setLocation(response.ajaxRedirect);
                        }
                    } else {
                        $(area).update(transport.responseText);
                    }
                }
                catch (e) {
                    $(area).update(transport.responseText);
                }
            }
        });
    }
}

CopyvarienForm.prototype = {
    initialize : function(formId, validationUrl){
        this.formId = formId;
        this.validationUrl = validationUrl;
        this.submitUrl = false;

        if($(this.formId)){
            this.validator  = new Validation(this.formId, {onElementValidate : this.checkErrors.bind(this)});
        }
        this.errorSections = $H({});
    },

    checkErrors : function(result, elm){
        if(!result)
            elm.setHasError(true, this);
        else
            elm.setHasError(false, this);
    },

    validate : function(){
        if(this.validator && this.validator.validate()){
            if(this.validationUrl){
                this._validate();
            }
            return true;
        }
        return false;
    },

    submit : function(url){
        if (typeof varienGlobalEvents != undefined) {
            varienGlobalEvents.fireEvent('formSubmit', this.formId);
        }
        this.errorSections = $H({});
        this.canShowError = true;
        this.submitUrl = url;
        if(this.validator && this.validator.validate()){
            if(this.validationUrl){
                this._validate();
            }
            else{
                this._submit();
            }
            return true;
        }
        return false;
    },

    _validate : function(){
        new Ajax.Request(this.validationUrl,{
            method: 'post',
            parameters: $(this.formId).serialize(),
            onComplete: this._processValidationResult.bind(this),
            onFailure: this._processFailure.bind(this)
        });
    },

    _processValidationResult : function(transport){
        if (typeof varienGlobalEvents != undefined) {
            varienGlobalEvents.fireEvent('formValidateAjaxComplete', transport);
        }
        var response = transport.responseText.evalJSON();
        if(response.error){
            if($('messages')){
                $('messages').innerHTML = response.message;
            }
        }
        else{
            this._submit();
        }
    },

    _processFailure : function(transport){
        location.href = BASE_URL;
    },

    _submit : function(){
        var $form = $(this.formId);
        if(this.submitUrl){
            $form.action = this.submitUrl;
        }
        $form.submit();
    }
};