In this article I will explain with an example, how to solve the error related to FromSql function of Entity Framework in .Net Core 2.1.
Error: DBSet<Entity> does not contain a definition for FromSql
The above error occurs because the namespace required to use the FromSql function has not been inherited.
The FromSql function belongs to the Microsoft.EntityFrameworkCore namespace.
Database
Here I am making use of Microsoft’s Northwind Database. You can download it from here.
Stored Procedure
You will need to create the following Stored Procedure in the Northwind Database. The Stored Procedure accepts @ContactName parameter which is used to perform a search on the records in Customers Table.
CREATE PROCEDURE Customers_SearchCustomers
@ContactName NVARCHAR(30)
AS
BEGIN
SET NOCOUNT ON;
SELECT TOP 10 *
FROM Customers
WHERE ContactName LIKE '%' + @ContactName + '%'
END
Model
The Model class consists of the following four properties.
public class Customer
{
public string CustomerID { get; set; }
public string ContactName { get; set; }
public string City { get; set; }
public string Country { get; set; }
}
Database Context
The very first step is to create Database Context.
Inside the class, first inherit the EntityFrameworkCore namespace and then inherit the DbContext class.
Then using Dependency Injection, a Constructor is created DbContextOptions are passed as parameter and also the Constructor of base class i.e. DbContext class is inherited.
A DbSet Collection property of Customer Entity is created, which will be later used for holding the Data fetched from SQL Server Database Table.
Finally, there is a method SearchCustomers which is used to call the Stored Procedure and return its result.
The Stored Procedure is called using the FromSql function. The FromSql function accepts the following two parameters:
1. SQL Query – SQL Query to execute the Stored Procedure.
2. Parameters – One or more objects of SqlParameter class.
Note: The FromSql function belongs to the Microsoft.EntityFrameworkCore namespace.
using System.Linq;
using System.Data.SqlClient;
using Microsoft.EntityFrameworkCore;
namespace Search_EF_MVC_Core
{
public class DBCtx : DbContext
{
public DBCtx(DbContextOptions<DBCtx> options) : base(options)
{
}
public DbSet<Customer> Customers { get; set; }
public IQueryable<Customer> SearchCustomers(string contactName)
{
SqlParameter pContactName = new SqlParameter("@ContactName", contactName);
return this.Customers.FromSql("EXECUTE Customers_SearchCustomers @ContactName", pContactName);
}
}
}
Controller
The Entity Framework is now configured and hence now we can create a Controller and write code to fetch the records from the Customers Table of the Northwind Database.
The Controller consists of two Action methods.
Action method for handling GET operation
Inside the Index Action method, the SearchCustomers method of the Database Context class is called and an empty string is passed as parameter.
Finally, the returned results are converted into Generic List collection and returned to the View.
Action method for handling POST operation
When the Form is submitted, the value of the Customer Name TextBox is submitted to this Action method and the received value is passed as parameter to the SearchCustomers function.
Finally, the returned results are converted into Generic List collection and returned to the View.
public class HomeController : Controller
{
private DBCtx Context { get; }
public HomeController(DBCtx _context)
{
this.Context = _context;
}
public IActionResult Index()
{
List<Customer> customers = this.Context.SearchCustomers("").ToList();
return View(customers);
}
[HttpPost]
public IActionResult Index(string customerName)
{
List<Customer> customers = this.Context.SearchCustomers(customerName).ToList();
return View(customers);
}
}
View
Inside the View, in the very first line the generic list of Customer Entity is declared as Model for the View.
The View consists of an HTML Form with following ASP.Net Tag Helpers attributes, a HTML TextBox and a Submit Button.
asp-action – Name of the Action. In this case the name is Index.
asp-controller – Name of the Controller. In this case the name is Home.
method – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
When the Search button is clicked, the Form gets submitted.
For displaying the records, an HTML Table is used. A loop will be executed over the Model which will generate the HTML Table rows with the Customer records.
@using Search_EF_MVC_Core;
@addTagHelper*, Microsoft.AspNetCore.Mvc.TagHelpers
@model List<Customer>
@{
Layout = null;
}
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width" />
<title>Index</title>
</head>
<body>
<form method="post" asp-controller="Home" asp-action="Index">
<span>Customer Name:</span><input type="text" name="CustomerName" />
<input type="submit" value="Search" />
<br />
<br />
<table cellpadding="0" cellspacing="0">
<tr>
<th>Customer Id</th>
<th>Contact Name</th>
<th>City</th>
<th>Country</th>
</tr>
@foreach (Customer customer in Model)
{
<tr>
<td>@customer.CustomerID</td>
<td>@customer.ContactName</td>
<td>@customer.City</td>
<td>@customer.Country</td>
</tr>
}
</table>
</form>
</body>
</html>
Screenshots
HTML Table displaying Top 10 records
![Entity Framework Core 2.1 Error: DBSet<Entity> does not contain a definition for FromSql]()
HTML Table displaying Filtered records
![Entity Framework Core 2.1 Error: DBSet<Entity> does not contain a definition for FromSql]()
Downloads
