ExtJS 4.2: Use checkbox in grid toolbar to manage a custom filter (remote filtering and ExtDirectSpring)

ContractSearchGrid.js

    (1) Define the custom filter
   
        me.activeFilter = Ext.create('Ext.util.Filter', {
            id: 'activeFilter',
            property: 'onlyActive',
            value: true
        });
   
   (2) In the grid panel, define the checkbox in the toolbar
   
        tbar: [
            {
                {
                    xtype: 'checkbox',
                    boxLabel: 'Show only active contracts',
                    itemId: 'showActiveOnly',
                    hideLabel: true,
                    margin: '0 10 0 20',
                    inputValue: 'true',
                    value: 'false',
                    listeners: {
                        change: function (cb, newValue, oldValue) {
                            me.showOnlyActive(newValue);
                        }
                    }
                }
            }
        ]
   
   (3) Define the method to apply/remove the filter
    
        showOnlyActive: function (newValue) {
            var me = this;
            if (newValue) {
                me.store.filter(me.activeFilter);
            } else {
                me.store.filters.removeAtKey('activeFilter');
                me.store.filter();
            }
        }
        
    (4) The store:
    
        Ext.define('scas.store.ContractMaster', {
            extend: 'Ext.data.Store',
        
            requires: [
                'scas.model.ContractMaster',
                'Ext.data.reader.Json'
            ],
        
            model: 'scas.model.ContractMaster',
        
            autoLoad: false,
        
            remoteSort: true,
            remoteFilter: true,
        
            pageSize: 100,
        
            proxy: {
                type: 'direct',
                api: {
                    read: contractMasterController.getContractMasterList
                },
                reader: {
                    type: 'json',
                    root: 'records',
                    totalProperty: 'total'
                }
            }
        
        });
                    
    (5) On the server, process the filter (using ExtDirectStoreReadRequest request)
    
        StringBuilder where = new StringBuilder();
        where.append(" where ");

        // String filter with name of "filter" overrides querystring in request.
        if (request.getFilters().size() > 0) {
            for (int i = 0; i < request.getFilters().size(); i++) {
                Filter filter = request.getFilters().get(i);
                if (filter.getField().equals("onlyActive")) {
                    if (((BooleanFilter) filter).getValue()) {
                        Long now = DateTime.now().getMillis();
                        where.append(" contractExpDts >= " + now + " ");
                    }
                }
                // Handle other (filters here)
            }
        }
        
        After querying, the method returns:
        
        return new ExtDirectStoreReadResult<ContractMasterSdo>(totalRecords, contractMasterSdos);