From 801502154fef03e4d6a2fd6128899aa958cb66bb Mon Sep 17 00:00:00 2001
From: Felix Ouk <felix.ouk@gmail.com>
Date: Sat, 10 Feb 2018 22:26:23 -0800
Subject: [PATCH] Add comment to explain type cast

---
 src/components/data-pane/wildcard-field-drop-zone.tsx | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/components/data-pane/wildcard-field-drop-zone.tsx b/src/components/data-pane/wildcard-field-drop-zone.tsx
index 489686430..0894d343b 100644
--- a/src/components/data-pane/wildcard-field-drop-zone.tsx
+++ b/src/components/data-pane/wildcard-field-drop-zone.tsx
@@ -56,6 +56,9 @@ const customWildcardFieldTarget: DropTargetSpec<CustomWildcardFieldDropZoneProps
       return;
     }
 
+    // Casting to DraggedFieldIdentifier because of bad TS type inference
+    // It does not realize that the object contains the property `fieldDef`
+    // We do the same thing in `encoding-shelf.tsx for `encodingShelfTarget`
     const {fieldDef} = monitor.getItem() as DraggedFieldIdentifier;
     const type = fieldDef.type;
 
@@ -81,6 +84,9 @@ const customWildcardFieldTarget: DropTargetSpec<CustomWildcardFieldDropZoneProps
     });
   },
   canDrop(props, monitor) {
+    // Casting to DraggedFieldIdentifier because of bad TS type inference
+    // It does not realize that the object contains the property `fieldDef`
+    // We do the same thing in `encoding-shelf.tsx for `encodingShelfTarget`
     const {fieldDef} = monitor.getItem() as DraggedFieldIdentifier;
     return fieldDef.field !== '*';
   }