Change and save record by custom button

Hi!

I need a custom button that will change value in a recaord and then save this record. I've tried it on a OpportunitySectionV2 with this code

 

define("OpportunitySectionV2", [], function() {
	return {
		entitySchemaName: "Opportunity",
		details: /**SCHEMA_DETAILS*/{}/**SCHEMA_DETAILS*/,
		diff: /**SCHEMA_DIFF*/[ 
            {
                "operation": "insert",
                "parentName": "ActionButtonsContainer",
                "propertyName": "items",
                "name": "MainContactSectionButton",
                "values": {
                    itemType: Terrasoft.ViewItemType.BUTTON,
                    caption: { bindTo: "Resources.Strings.OpenPrimaryContactButtonCaption" },
                    click: { bindTo: "onOpenPrimaryContactClick" },
                    "layout": {
                        "column": 1,
                        "row": 6,
                        "colSpan": 1
                    }
                }
            }]/**SCHEMA_DIFF*/,
		methods: {
			prepareResponseCollectionItem: function(item) {
				this.callParent(arguments);
         		if (item.get("MgtImportantFlg") === false){
					item.customStyle = Ext.apply({}, {
					  "background-color": "#cc081c",
					  "font-family": "cursive"
					}, item.customStyle);		  		
		  		}
			},
			onOpenPrimaryContactClick: function(){
				var activeRow = this.get("ActiveRow");
				var bFlag = this.get("GridData").get(activeRow).get("MgtImportantFlg");
					if(bFlag){
						this.get("GridData").get(activeRow).set("MgtImportantFlg",false);
						this.save();
					}
					else{
						this.get("GridData").get(activeRow).set("MgtImportantFlg",true);
						this.save();
					}
			}
		}
	};
});

it change the value in my field but didn`t save it, so after reload shows old value.

Could anyone help me how should i change code for my purposes?