Let UIStore trigger element fetching when collection is selected

Store currentCollectionID in UIStore

app/assets/javascripts/components/CollectionSubtree.js

@@ -27,15 +27,8 @@ export default class CollectionSubtree extends React.Component {
     UIStore.unlisten(this.onChange.bind(this));
   }
 
-  componentWillUpdate(nextProps, nextState) {
-    if(nextState.selected) {
-      // TODO also for reactions and so on
-      ElementActions.fetchSamplesByCollectionId(this.state.root.id)
-    }
-  }
-
   onChange(state) {
-    if(state.selectedCollectionIds[0] == this.state.root.id) {
+    if(state.currentCollectionId == this.state.root.id) {
       this.setState({selected: true});
     } else {
       this.setState({selected: false});

app/assets/javascripts/components/stores/UIStore.js

 import alt from '../alt';
 import UIActions from '../actions/UIActions';
+import ElementActions from '../actions/ElementActions';
 import ElementStore from './ElementStore';
 
 import ArrayUtils from '../utils/ArrayUtils';
@@ -9,7 +10,7 @@ class UIStore {
   constructor() {
     this.state = {
       checkedSampleIds: Immutable.List(),
-      selectedCollectionIds: []
+      currentCollectionId: null
     };
 
     this.bindListeners({
@@ -60,7 +61,7 @@ class UIStore {
   handleDeselectAllElements(type) {
     switch(type) {
       case 'collection':
-        this.state.selectedCollectionIds = [];
+        this.state.currentCollectionId = null;
         break;
     }
   }
@@ -68,7 +69,9 @@ class UIStore {
   handleSelectElement(element) {
     switch(element.type) {
       case 'collection':
-        this.state.selectedCollectionIds.push(element.id);
+        this.state.currentCollectionId = element.id;
+        // TODO also for reactions and so on
+        ElementActions.fetchSamplesByCollectionId(element.id)
         break;
     }
   }