#4398 - Added validation to the grid editor, such that columns must be at least as large as the layouts.

src/Umbraco.Web/PropertyEditors/GridConfigurationEditor.cs

@@ -1,4 +1,9 @@
-using Umbraco.Core.PropertyEditors;
+using System.Collections.Generic;
+using System.ComponentModel.DataAnnotations;
+using System.Linq;
+using Newtonsoft.Json;
+using Umbraco.Core.PropertyEditors;
+using Umbraco.Core.PropertyEditors.Validators;
 
 namespace Umbraco.Web.PropertyEditors
 {
@@ -6,5 +11,45 @@ namespace Umbraco.Web.PropertyEditors
     /// Represents the configuration for the grid value editor.
     /// </summary>
     public class GridConfigurationEditor : ConfigurationEditor<GridConfiguration>
-    { }
+    {
+        public GridConfigurationEditor()
+        {
+            var items = Fields.First(x => x.Key == "items");
+
+            items.Validators.Add(new GridValidator());
+        }
+    }
+
+    public class GridValidator : IValueValidator
+    {
+        public IEnumerable<ValidationResult> Validate(object rawValue, string valueType, object dataTypeConfiguration)
+        {
+            if (rawValue == null)
+                yield break;
+
+            var model = JsonConvert.DeserializeObject<GridEditorModel>(rawValue.ToString());
+
+            if (model.Templates.Any(t => t.Sections.Sum(s => s.Grid) > model.Columns))
+            {
+                yield return new ValidationResult("Columns must be at least the same size as the largest layout", new[] { nameof(model.Columns) });
+            }
+
+        }
+    }
+
+    public class GridEditorModel
+    {
+        public GridEditorTemplateModel[] Templates { get; set; }
+        public int Columns { get; set; }
+    }
+
+    public class GridEditorTemplateModel
+    {
+        public GridEditorSectionModel[] Sections { get; set; }
+    }
+
+    public class GridEditorSectionModel
+    {
+        public int Grid { get; set; }
+    }
 }