feat(examples): add datasource plugin example

examples/datasource-plugin-genericdatasource/src/query_ctrl.js

@@ -0,0 +1,26 @@
+import {QueryCtrl} from 'app/plugins/sdk';
+import './css/query-editor.css!'
+
+export class GenericDatasourceQueryCtrl extends QueryCtrl {
+
+  constructor($scope, $injector, uiSegmentSrv)  {
+    super($scope, $injector);
+
+    this.scope = $scope;
+    this.uiSegmentSrv = uiSegmentSrv;
+    this.target.target = this.target.target || 'select metric';
+  }
+
+  getOptions() {
+    return this.datasource.metricFindQuery(this.target)
+      .then(this.uiSegmentSrv.transformToSegments(false));
+      // Options have to be transformed by uiSegmentSrv to be usable by metric-segment-model directive
+  }
+
+  onChangeInternal() {
+    this.panelCtrl.refresh(); // Asks the panel to refresh data.
+  }
+}
+
+GenericDatasourceQueryCtrl.templateUrl = 'partials/query.editor.html';
+