get random data with entity framework

Question

How can i get random data from database with entity framework, *vers. 6

Answer 1

Without specifics, here is how to get random records from a model.

public static List<Products> RandomProducts(int count)  
{  
    using var context = new Context();  
      
    Random rand = new Random();  
    int skipper = rand.Next(0, context.Products.Count());  
  
    return context  
        .Products  
        .OrderBy(product => Guid.NewGuid())  
        .Skip(skipper)  
        .Take(count)  
        .ToList();  
}  

Usage

var products = CoreOperations.RandomProducts(7);  
foreach (var product in products)  
{  
    Console.WriteLine($"{product.ProductId,-4}{product.ProductName}");  
}  
  

Edit, here is a generic method

/// <summary>  
/// Get list of random records for <see cref="TModel"/> by <see cref="count"/>  
/// </summary>  
/// <typeparam name="TModel">Model to read</typeparam>  
/// <param name="count">Max records</param>  
/// <returns>List of <see cref="TModel"/></returns>  
/// <remarks>  
/// Not guaranteed to return <see cref="count"/> but will return records  
/// </remarks>  
public static List<TModel> Random<TModel>(int count) where TModel : class  
{  
    using var context = new Context();  
  
    Random rand = new Random();  
    int skipper = rand.Next(0, context.Set<TModel>().Count());  
    return context.Set<TModel>().ToList()  
        .OrderBy(x => Guid.NewGuid())  
        .Skip(skipper)  
        .Take(count).ToList();  
}  

Usage

List<Products> products = CoreOperations.Random<Products>(7);  
foreach (var product in products)  
{  
    Console.WriteLine($"{product.ProductId,-4}{product.ProductName}");  
}  
  
Console.WriteLine();  
  
List<Categories> categories = CoreOperations.Random<Categories>(3);  
foreach (var product in categories)  
{  
    Console.WriteLine($"{product.CategoryId,-4}{product.CategoryName}");  
}  

Answer 2

Hi,

Initially, you need to get the random number from 1 to max record as shown:

Random rand = new Random();  
int toSkip = rand.Next(1, db.MyTables.Count);  

Then you can use order by you can use the Guid.NewGuid() as shown in below sample.

 db.MyTables.OrderBy(x=>x.Guid.NewGuid()).Skip(toSkip).Take(5).ToList()  

That's it.