Merge pull request #494 from uglymunky/subclassing-grid-columns

[fix #486] inherit columns from Constructor

Author: wyuenho

lib/backgrid.js

@@ -2761,7 +2761,7 @@ var Grid = Backgrid.Grid = Backbone.View.extend({
     // Convert the list of column objects here first so the subviews don't have
     // to.
     if (!(options.columns instanceof Backbone.Collection)) {
-      options.columns = new Columns(options.columns);
+      options.columns = new Columns(options.columns || this.columns);
     }
     this.columns = options.columns;
 

src/grid.js

@@ -85,7 +85,7 @@ var Grid = Backgrid.Grid = Backbone.View.extend({
     // Convert the list of column objects here first so the subviews don't have
     // to.
     if (!(options.columns instanceof Backbone.Collection)) {
-      options.columns = new Columns(options.columns);
+      options.columns = new Columns(options.columns || this.columns);
     }
     this.columns = options.columns;
 

test/grid.js

@@ -140,4 +140,20 @@ describe("A Grid", function () {
     expect($(tbody).find("tr:nth-child(3) > td.integer-cell.editable.sortable.renderable").text()).toBe("3");
   });
 
+  it("will inherit the constructor's columns", function () {
+    var columns = [{
+      name: "title",
+      cell: "string"
+    }];
+
+    var CustomGrid = Backgrid.Grid.extend({
+      columns: columns
+      , className: 'backgrid customBackgrid'
+    });
+
+    var customGrid = new CustomGrid({collection: books});
+
+    expect(customGrid.columns.models.length).toBe(1);
+    expect(customGrid.columns.at(0).get("name")).toBe("title");
+  });
 });