Allows you to efficiently compose an IEnumerable<T> in your Entity Framework Core queries when using the SQL Server Database Provider. This is accomplished by using the AsQueryableValues extension method available on the DbContext class. Everything is evaluated on the server with a single round trip, in a way that preserves the query's execution plan, even when the values behind the IEnumerable<T> are changed on subsequent executions.
The provided AsQueryableValues extension method on the DbContext class allows us to efficiently compose an IEnumerable in our queries when it consist of non-constant values. It returns an IQueryable that in the context of a query can be treated as any other entity in our DbContext. Everything is evaluated on the server.
The supported types for T are: Int32, Int64, Decimal, Double, DateTime, DateTimeOffset, Guid, and String.
For a detailed explanation, please continue reading here.
When Should I Use It?
The AsQueryableValues extension method is intended for queries that are dependent on a non-constant sequence of external values. In this case, the underline SQL query will be efficient on subsequent executions.
Getting Started
Installation
QueryableValues is distributed as a NuGet Package. The major version number of this library is aligned with the version of Entity Framework Core that's supported by it; for example, if you are using EF Core 5, then you must use version 5 of QueryableValues.
Please choose the appropriate command below to install it using the NuGet Package Manager Console window in Visual Studio:
Look for the place in your code where you are setting up your DbContext and calling the UseSqlServer extension method, then use a lambda expression to access the SqlServerDbContextOptionsBuilder provided by it. It is on this builder that you must call the UseQueryableValues extension method, as shown in the following simplified examples:
When using the OnConfiguring method inside your DbContext:
using BlazarTech.QueryableValues;
public class MyDbContext : DbContext
{
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
optionsBuilder.UseSqlServer(
"MyConnectionString",
sqlServerOptionsBuilder =>
{
sqlServerOptionsBuilder.UseQueryableValues();
}
);
}
}
When setting up the DbContext at registration time using dependency injection:
using BlazarTech.QueryableValues;
public class Startup
{
public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext<MyDbContext>(optionsBuilder => {
optionsBuilder.UseSqlServer(
"MyConnectionString",
sqlServerOptionsBuilder =>
{
sqlServerOptionsBuilder.UseQueryableValues();
}
);
});
}
}
How Do I Use It?
The AsQueryableValues extension method is provided by the BlazarTech.QueryableValues namespace, therefore, you must add the following using directive to your source code file in order for it to appear as a method of your DbContext instance.
using BlazarTech.QueryableValues;
Below are two patterns that you can use to retrieve data from an entity based on values provided by an IEnumerable.
// Sample values.
IEnumerable<int> values = Enumerable.Range(1, 10);
// Example #1 (LINQ method syntax)
var myQuery1 = dbContext.MyEntities
.Join(
dbContext.AsQueryableValues(values),
i => i.MyEntityID,
v => v,
(i, v) => new
{
i.MyEntityID,
i.PropA
}
);
// Example #2 (LINQ query syntax)
var myQuery2 =
from i in dbContext.MyEntities
join v in dbContext.AsQueryableValues(values) on i.MyEntityID equals v
select new
{
i.MyEntityID,
i.PropA
});
