Group by Multiple Columns in LINQ C#

In this article, we will learn the Group y multiple Columns in LINQ C#. The ‘group by ‘method in LINQ to group data based on one or more columns.

Here’s an example of how to Group by multiple columns using LINQ in C#.

Table of Contents

Create an Asp.NET Core MVC or Web API Project

Assuming you have Visual Studio 2019 or Visual Studio 2022 installed, follow these steps to create a new ASP.NET Core Project

Open the visual studio (IDE).
Click on the “Create new project” option.
Choose “ASP.NET Core Web Application” from the list of available templates.
Click the Next button.
The configure a new project, specify the name and location of your project.
Click the “Next” button.
Then select .Net Core as the runtime and choose the version from the dropdown list at the top.
Make sure to uncheck the checkboxes for “Enable Docker Support” and “Configure for HTTPS” since we won’t be using authentication.
Click the “Create” button

Consider an example Employee class with properties like FirstName, LastName, City, and State. We’ll group employees based on their City and State.

Create a Model

namespace WEB_API_without_EF.Models
{
    public class Employees
    {
        public int ID { get; set; }
        public string Company { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string Email { get; set; }
        public string JobTitle { get; set; }
        public string Address { get; set;}

        public string City { get; set; }

        public string state { get; set; }

    }
}

Create a Controller


namespace WEB_API_without_EF.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    public class EmployeeController : ControllerBase
    {

        [HttpGet("GetgroupBy")]
        public IActionResult GetgroupBy()
        {
            List<Employees> employees = new List<Employees>
            {
                new Employees{FirstName="Anna", LastName="Bedecs", Company="Company A", City="Seattle",state="WA"},
                new Employees{FirstName="Antonio", LastName="Gratacos Solsona", Company="Company B", City="Boston",state="MA"},
                new Employees{FirstName="Thomas" ,LastName="Axen", Company="Company C", City="Seattle",state="WA"},
                new Employees{FirstName="Christina", LastName="Lee", Company="Company D", City="New York",state="NY"},
                new Employees{FirstName="Martin" ,LastName="O’Donnell", Company="Company E", City="Minneapolis",state="MN"},
                new Employees{FirstName="Francisco", LastName="Pérez-Olaeta", Company="Company F", City="Milwaukee",state="WI"},

            };

            var groupemployee = from emp in employees
                                group emp by new { emp.City, emp.state } into empgroup
                                select new
                                {
                                   Name =$"City : {empgroup.Key.City} State : {empgroup.Key.state}",
                                   employees= empgroup.ToList(),
                                };
            
      

            return Ok(groupemployee);

        }
}
}

Output: