Added edgeEventType constants, changed hardcoded values

@@ -376,6 +376,19 @@ export default angular.module('thingsboard.types', [])
                 entityView: "ENTITY_VIEW",
                 edge: "EDGE"
             },
+            edgeEventType:{
+                dashboard: "DASHBOARD",
+                asset: "ASSET",
+                device: "DEVICE",
+                entityView: "ENTITY_VIEW",
+                alarm: "ALARM",
+                rulechain: "RULE_CHAIN",
+                ruleChainMetaData: "RULE_CHAIN_METADATA",
+                edge: "EDGE",
+                user: "USER",
+                customer: "CUSTOMER",
+                relation: "RELATION"
+            },
             importEntityColumnType: {
                 name: {
                     name: 'import.column-type.name',

@@ -100,10 +100,10 @@ export default function EventRowDirective($compile, $templateCache, $mdDialog, $
             }
             var content = '';
             switch(scope.event.edgeEventType) {
-                case 'RELATION':
+                case types.edgeEventType.relation:
                     content = angular.toJson(scope.event.entityBody);
                     break;
-                case 'RULE_CHAIN_METADATA':
+                case types.edgeEventType.ruleChainMetaData:
                     content = ruleChainService.getRuleChainMetaData(scope.event.entityId, {}).then(
                         function success(info) {
                             return angular.toJson(info);

@@ -100,7 +100,7 @@ export default function EventTableDirective($compile, $templateCache, $rootScope
             fetchMoreItems_: function () {
                 if (scope.events.hasNext && !scope.events.pending) {
                     if (scope.entityType && scope.entityId && scope.eventType && scope.tenantId) {
-                        if (scope.eventType !== "EDGE_EVENT") {
+                        if (scope.eventType !== types.eventType.edgeEvent.value) {
                             var promise = eventService.getEvents(scope.entityType, scope.entityId,
                                 scope.eventType, scope.tenantId, scope.events.nextPageLink);
                         } else {