Check byte array contains byte array linq c# - linq

Question

I need to check if an byte[] entity attribute contains an string. I tried everything I found but Linq seems to be pretty tight and doesn't allow me to use my custom methods so any idea?
I tried converting the string (Content) to byte array an then using a custom method check if my entity attribute (x.Document) contains the string converted(ContentBytes) with no success due to linq seems that it doesn't allow you to use methods it can't convert to plain SQL so I dont know how to get it.
using (GPC container = new GPC()) {
var p = from t in ...
select t;
if (Content != null) {
byte[] ContentBytes = System.Text.Encoding.ASCII.GetBytes(Content);
p = p.Where(x => this.CheckPatternInArray(x.Document, ContentBytes) == true);
}
private bool CheckPatternInArray(byte[] array, byte[] pattern) {
int fidx = 0;
int result = Array.FindIndex(array, 0, array.Length, (byte b) => {
fidx = (b == pattern[fidx]) ? fidx + 1 : 0;
return (fidx == pattern.Length);
});
return (result >= pattern.Length - 1);
}
Any idea?

Answer 1

In the comparison can you do other way around? I mean, if you know the encoding then u can convert the x.Document to string. Then comparing the string will be very easy.
System.Text.UTF8Encoding enc = new System.Text.UTF8Encoding();
string s = enc.GetString(x.Document);
You don't need o write a extension function.

Answer 2

As for creating an extension method, here is one I made to make it easier to inspect the progress of a linq expression:
public static class LinqUtilities
{
/// <summary>
/// Inject this in your Linq chains to inspect each item as it is processed.
///
/// The item can be changed during the "tap" operation, but a new item cannot be created
///
/// Use this for logging or for in-line audits (summaries, secondary list creation...) or anything else that catches your fancy!
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="this"></param>
/// <param name="tapper">function to observe the current object</param>
/// <returns></returns>
public static IEnumerable<T> Tap<T>(this IEnumerable<T> #this, Action<T> tapper)
{
foreach (var item in #this)
{
tapper(item);
yield return item;
}
}
}

Answer 3

Here is some PSEUDO-CODE to give an idea of what I'm thinking. I make no promises that it will compile, much less run. But it should point you in the right direction for your original question.
I declare 4 arrays; one that has the values we want to check for, and three test arrays. Then I run the expression against each array to show what the output would be.
char[] toCheck = {'a', 'b', 'c', 'd'};
char[] hasAll = {'a', 'b', 'c', 'd', 'e', 'f', 'g'};
char[] hasSome = {'c', 'd', 'e', 'f', 'g'};
char[] hasNone = {'e', 'f', 'g'};
// verify the linq expression works by comparing against the different arrays
char[] foundList = toCheck.Except(v => hasAll.indexOf(v) >= 0);
// foundList.count == 0
foundList = toCheck.Except(v => hasSome.indexOf(v) >= 0);
// foundList.count == 2
foundList = toCheck.Except(v => hasNone.indexOf(v) >= 0);
// foundList.count == 0