Linq to Entities, Random Order

Linq to Entities, random order

The simple solution would be creating an array (or a List<T>) and than randomize its indexes.

EDIT:

static IEnumerable<T> Randomize<T>(this IEnumerable<T> source) {
  var array = source.ToArray();
  // randomize indexes (several approaches are possible)
  return array;
}

EDIT: Personally, I find the answer of Jon Skeet is more elegant:

var results = from ... in ... where ... orderby Guid.NewGuid() select ...

And sure, you can take a random number generator instead of Guid.NewGuid().

linq: order by random

http://msdn.microsoft.com/en-us/library/system.guid.newguid.aspx

return (from examQ in idb.Exam_Question_Int_Tbl
      where examQ.Exam_Tbl_ID==exam_id
      select examQ).OrderBy(x => Guid.NewGuid()).Take(50);

If this is LINQ-to-SQL you could simply add a ORDER BY NEWID() to your SELECT statement.

As commented it might be better to use an algorithm like Fisher-Yates Shuffle, here is an implementation: https://stackoverflow.com/a/375446/284240

EF Code First: How to get random rows

Just call:

something.OrderBy(r => Guid.NewGuid()).Take(5)

Random sort list with LINQ and Entity Framework

You can't use a Random object in the query like that, as the object exists in your VB code, not in the database.

Get the result into a list first, then scramble it. It's much more efficient to use a scrambling algorithm like Fischer-Yates/Knuth than sorting on a random value:

Dim rnd as New Random()
For i As Integer = gardens.Count To 2 Step -1
  Dim pos As Integer = rnd.Next(i)
  Dim x = gardens(i - 1)
  gardens(i - 1) = gardens(pos)
  gardens(pos) = x
Next

Also, to sort on a random value you either have to know that the sorting algorithm won't ever reevaluate the relation between two given items, or you have to assign a random value to each item so that it uses the same value throughout the sorting. If the method that you tried would have been possible, you could have gotten the same bad result as for the browser choise page.

Randomize entity framework query results

this turned out to be very simple using extension methods, ordering by name first, then calling Take (top on T-sql) and randomizing later

        context.Categories().OrderByName().Take(20).OrderByRandom();

        public static IQueryable<Category> OrderByName(this IQueryable<Category> query)
        {
                return from c in query
                        orderby c.Name
                        select c;
        }

        public static IQueryable<T> OrderByRandom<T>(this IQueryable<T> query)
        {
                return (from q in query
                        orderby Guid.NewGuid()
                        select q);
        }

Linq order by random without GUID

If you want to return results in random order, but that order will be the same if you are sending same string from client, then you can use Random class to get pseudo-random order. This random generator can accept seed - a value, which is used to calculate starting value of pseudo-random sequence. Thus you are passing string you can use it's hash code to get integer value for seed:

        var seed = randomstring.GetHashCode();
        var random = new Random(seed);

        var channels = db.Channels
           .Where(x => (id == 0) || (x.CategoryId == id))
           .Where(q => word == "0" || (q.Title.Contains(word) || q.Desc.Contains(word)))
           .AsEnumerable() // randomizing should happen on client side
           .OrderBy(x => random.Next())
           .Skip(skip)
           .Take(pageSize)
           .ToList();    

What is Guid.NewGuid() doing in LINQ to Entities?

This behavior when you have Guid.NewGuid() is by design in Entity Framework, it mimics SQL's ORDER BY NEWID(), to allow random ordering. When you specify a constant Guid, it merely orders by this constant value.

Picking random record from Entity Framework database without OrderBy

You can have something like :

personToCall = db.Persons.OrderBy(r => Guid.NewGuid()).Skip(toSkip).Take(1).First();

You should use FirstOrDefault to be mode defensive.

Here the dark lord teaching the force to yoda! what is the world coming to!

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