kartik\export\ExportMenu::generateBody PHP Method

    public function generateBody()
    {
        $this->_endRow = 0;
        $columns = $this->getVisibleColumns();
        $models = array_values($this->_provider->getModels());
        if (count($columns) == 0) {
            $cell = $this->_objPHPExcelSheet->setCellValue('A1', $this->emptyText, true);
            $model = reset($models);
            $this->raiseEvent('onRenderDataCell', [$cell, $this->emptyText, $model, null, 0, $this]);
            return 0;
        }
        // do not execute multiple COUNT(*) queries
        $totalCount = $this->_provider->getTotalCount();
        $this->findGroupedColumn();
        while (count($models) > 0) {
            $keys = $this->_provider->getKeys();
            foreach ($models as $index => $model) {
                $key = $keys[$index];
                $this->generateRow($model, $key, $this->_endRow);
                $this->_endRow++;
                if ($index === $totalCount) {
                    //a little hack to generate last grouped footer
                    $this->checkGroupedRow($model, $models[0], $key, $this->_endRow);
                } elseif (isset($models[$index + 1])) {
                    $this->checkGroupedRow($model, $models[$index + 1], $key, $this->_endRow);
                }
                if (!is_null($this->_groupedRow)) {
                    $this->_endRow++;
                    $this->_objPHPExcelSheet->fromArray($this->_groupedRow, null, "A" . ($this->_endRow + 1), true);
                    $cell = "A" . ($this->_endRow + 1) . ":" . self::columnName(count($columns)) . ($this->_endRow + 1);
                    $this->_objPHPExcelSheet->getStyle($cell)->applyFromArray($this->groupedRowStyle);
                    $this->_groupedRow = null;
                }
            }
            if ($this->_provider->pagination) {
                $this->_provider->pagination->page++;
                $this->_provider->refresh();
                $this->_provider->setTotalCount($totalCount);
                $models = $this->_provider->getModels();
            } else {
                $models = [];
            }
        }
        // Set autofilter on
        $this->_objPHPExcelSheet->setAutoFilter(self::columnName(1) . $this->_beginRow . ":" . self::columnName($this->_endCol) . $this->_endRow);
        return $this->_endRow;
    }