1 files changed, 114 insertions, 0 deletions
diff --git a/src/Mvc/src/Microsoft.AspNetCore.Mvc.WebApiCompatShim/FormDataCollectionExtensions.cs b/src/Mvc/src/Microsoft.AspNetCore.Mvc.WebApiCompatShim/FormDataCollectionExtensions.cs
new file mode 100644
index 0000000000..a9539e83a0
--- /dev/null
+++ b/src/Mvc/src/Microsoft.AspNetCore.Mvc.WebApiCompatShim/FormDataCollectionExtensions.cs
@@ -0,0 +1,114 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Net.Http.Formatting;
+using System.Text;
+
+namespace Microsoft.AspNetCore.Mvc.WebApiCompatShim
+{
+    public static class FormDataCollectionExtensions
+    {
+        // This is a helper method to use Model Binding over a JQuery syntax.
+        // Normalize from JQuery to MVC keys. The model binding infrastructure uses MVC keys
+        // x[] --> x
+        // [] --> ""
+        // x[field]  --> x.field, where field is not a number
+        public static string NormalizeJQueryToMvc(string key)
+        {
+            if (key == null)
+            {
+                return string.Empty;
+            }
+
+            StringBuilder sb = null;
+            var i = 0;
+            while (true)
+            {
+                var indexOpen = key.IndexOf('[', i);
+                if (indexOpen < 0)
+                {
+                    // Fast path, no normalization needed.
+                    // This skips the string conversion and allocating the string builder.
+                    if (i == 0)
+                    {
+                        return key;
+                    }
+                    sb = sb ?? new StringBuilder();
+                    sb.Append(key, i, key.Length - i);
+                    break; // no more brackets
+                }
+
+                sb = sb ?? new StringBuilder();
+                sb.Append(key, i, indexOpen - i); // everything up to "["
+
+                // Find closing bracket.
+                var indexClose = key.IndexOf(']', indexOpen);
+                if (indexClose == -1)
+                {
+                    throw new ArgumentException(Resources.JQuerySyntaxMissingClosingBracket, nameof(key));
+                }
+
+                if (indexClose == indexOpen + 1)
+                {
+                    // Empty bracket. Signifies array. Just remove.
+                }
+                else
+                {
+                    if (char.IsDigit(key[indexOpen + 1]))
+                    {
+                        // array index. Leave unchanged.
+                        sb.Append(key, indexOpen, indexClose - indexOpen + 1);
+                    }
+                    else
+                    {
+                        // Field name.  Convert to dot notation.
+                        sb.Append('.');
+                        sb.Append(key, indexOpen + 1, indexClose - indexOpen - 1);
+                    }
+                }
+
+                i = indexClose + 1;
+                if (i >= key.Length)
+                {
+                    break; // end of string
+                }
+            }
+            return sb.ToString();
+        }
+
+        public static IEnumerable<KeyValuePair<string, string>> GetJQueryNameValuePairs(
+            this FormDataCollection formData)
+        {
+            if (formData == null)
+            {
+                throw new ArgumentNullException(nameof(formData));
+            }
+
+            var count = 0;
+
+            foreach (var kv in formData)
+            {
+                ThrowIfMaxHttpCollectionKeysExceeded(count);
+
+                var key = NormalizeJQueryToMvc(kv.Key);
+                var value = kv.Value ?? string.Empty;
+                yield return new KeyValuePair<string, string>(key, value);
+
+                count++;
+            }
+        }
+
+        private static void ThrowIfMaxHttpCollectionKeysExceeded(int count)
+        {
+            if (count >= MediaTypeFormatter.MaxHttpCollectionKeys)
+            {
+                var message = Resources.FormatMaxHttpCollectionKeyLimitReached(
+                    MediaTypeFormatter.MaxHttpCollectionKeys,
+                    typeof(MediaTypeFormatter));
+                throw new InvalidOperationException(message);
+            }
+        }
+    }
+}