bchavez/Bogus · error · ArgumentOutOfRangeException

{nameof(amountToPick)} is greater than the number of items.

Error message

{nameof(amountToPick)} is greater than the number of items.

What it means

Faker.PickRandom(items, amountToPick) throws ArgumentOutOfRangeException when amountToPick exceeds the number of items in the sequence, because Shuffle+Take cannot return more elements than exist.

Source

Thrown at Source/Bogus/Faker.cs:298

   {
      return this.Random.ArrayElement(items);
   }

   /// <summary>
   /// Helper to pick random subset of elements out of the list.
   /// </summary>
   /// <param name="amountToPick">amount of elements to pick of the list.</param>
   /// <exception cref="ArgumentException">if amountToPick is lower than zero.</exception>
   public IEnumerable<T> PickRandom<T>(IEnumerable<T> items, int amountToPick)
   {
      if( amountToPick < 0 )
      {
         throw new ArgumentOutOfRangeException($"{nameof(amountToPick)} needs to be a positive integer.");
      }
      var size = items.Count();
      if( amountToPick > size )
      {
         throw new ArgumentOutOfRangeException($"{nameof(amountToPick)} is greater than the number of items.");
      }
      return this.Random.Shuffle(items).Take(amountToPick);
   }

   /// <summary>
   /// Helper method to call faker actions multiple times and return the result as IList of T
   /// </summary>
   public IList<T> Make<T>(int count, Func<T> action)
   {
      return Enumerable.Range(1, count).Select(n => action()).ToList();
   }

   /// <summary>
   /// Helper method to call faker actions multiple times and return the result as IList of T.
   /// This method passes in the current index of the generation.
   /// </summary>
   public IList<T> Make<T>(int count, Func<int, T> action)
   {

View on GitHub (pinned to 6ece18c5c2)

Solutions

Clamp amountToPick to items.Count() (materialize once if enumerating multiple times).
Validate the source is non-empty and large enough before picking.
Use f.Random.Shuffle(items).Take(Math.Min(amountToPick, items.Count())) explicitly.

Example fix

// before
var subset = f.PickRandom(items, 10);

// after
var list = items as IList<T> ?? items.ToList();
var subset = f.PickRandom(list, Math.Min(10, list.Count));

Defensive patterns

Strategy: validation

Validate before calling

var list = items as IList<T> ?? items.ToList();
int amountToPick = Math.Clamp(requestedCount, 0, list.Count);
var subset = f.PickRandom(list, amountToPick);

Prevention

Materialize the source once if you need its count more than once.
Clamp amountToPick to the actual item count.
Handle empty sources explicitly before picking.

When it happens

Trigger: Calling f.PickRandom(items, 10) when items has fewer than 10 elements; calling with amountToPick larger than a filtered/empty source.

Common situations: Assuming a source list is large enough when it is empty or small; computing amountToPick from a page size larger than the data set.

Related errors

AI-assisted analysis of bchavez/Bogus@6ece18c5c2 (2026-08-13). Data as JSON: /api/errors/fd9088b592ff49d4. Report an issue: GitHub.