gistfile1.js

  onBeforePagingPageChanges: function(pagingToolbar) {
        var grid = pagingToolbar.up('grid[itemId="articlesListGrid"]');

        this.storeSelectedGridRecords(grid);
    },

    /**
     * Saves list of articles that were selected in given Grid.
     */
    storeSelectedGridRecords: function(grid) {
        var me = this;

        // Get reference to Grid's store
        var store = grid.getStore();

        // ... and get selection model ...
        var selectionModel = grid.getSelectionModel();

        // ... and finally get list of selected records and store it inside controller
        var selection = selectionModel.getSelection();


        var catalogId = store.catalog_id;

        selection = selection || [];

        // First I will remove selection from all articles that are found on current page.
        // This way I know that articles that user de-selected won't be left as selected
        // in our internal array.
        store.each(function(article) {
            var articleId = article.get('st_article_id');

            if (me.selectedArticlesList[catalogId] && me.selectedArticlesList[catalogId][articleId]) {
                delete me.selectedArticlesList[catalogId][articleId];
            }
        });

        Ext.each(selection, function(article) {
            if (!me.selectedArticlesList[catalogId]) {
                me.selectedArticlesList[catalogId] = {};
            }

            var articleId = article.get('st_article_id');

            me.selectedArticlesList[catalogId][articleId] = article;
        });
    },

    /**
     * Fires when user changes the page and that page has been loaded.
     */
    onAfterPagingPageHasBeenChanged: function(pagingToolbar) {
        var grid = pagingToolbar.up('grid[itemId="articlesListGrid"]');

        this.preselectAlreadySelectedRecords(grid);
    },

    preselectAlreadySelectedRecords: function(grid) {
        var me = this;

        // Get reference to Grid's store
        var store = grid.getStore();

        // ... and get selection model ...
        var selectionModel = grid.getSelectionModel();

        var catalogId = store.catalog_id;

        var recordsToPreselect = [];

        store.each(function(article) {
            var articleId = article.get('st_article_id');

            if (me.selectedArticlesList[catalogId] && me.selectedArticlesList[catalogId][articleId]) {
                recordsToPreselect.push(article);
            }
        });

        selectionModel.select(recordsToPreselect);
    }