Question

I have GridView and I need HTML ENCODE all values being update using Event handler _RowUpdating.

At the moment I use this script BUT I receive an error:

Collection was modified; enumeration operation may not execute.

---

Any idea how to make it works? Thanks for your help!

       foreach (DictionaryEntry entry in e.Keys)
        {
            e.Keys[entry.Key] = Server.HtmlEncode(entry.Value.ToString());              
        }

Answer 1

Three options:

1) Take a copy of all the entries to start with, so you’re not actually iterating over those and modifying them as you go.

2) Just iterate over a copy of the keys – again, to avoid modifying what you’re iterating over.

3) Build a new dictionary instead of modifying the existing one.

Given the skeleton code here:

using System;
using System.Collections.Generic;
using System.Linq;

class Test
{    
    static void Main()
    {
        var dict = new Dictionary<string, string>
        {
            { "X", "first" },
            { "Y", "second" },
            { "Z", "third" }
        };

        // INSERT DICTIONARY-CHANGING CODE HERE            

        foreach (var entry in dict)
        {
            Console.WriteLine("{0} = {1}", entry.Key, entry.Value);
        }
    }
}

… and taking “upper-casing” as a simple thing to test (just use Server.HtmlEncode in your real code), here are the three options (I’m assuming you have LINQ available to you):

1) Iterating over a copy of the entries:

    foreach (var entry in dict.ToList())
    {
        dict[entry.Key] = entry.Value.ToUpperInvariant();
    }

2) Iterating over a copy of the keys:

    foreach (string key in dict.Keys.ToList())
    {
        dict[key] = dict[key].ToUpperInvariant();
    }

3) Creating a new dictionary (and then assigning the reference back to the dict variable):

    dict = dict.ToDictionary(entry => entry.Key,
                             entry => entry.Value.ToUpperInvariant());