How to build server url for DTOs

Question

I want to add a url to my DTOs, specifically a canonical link for each object in a collection. I'm using Dapper to map my SQL result into a collection, so I was hoping to do this within the POCO itself.

public class Group {
 public string Name { get; set; }
 public string url {
  get {
    //CODE TO BUILD LINK HERE (e.g., https://example.com/v1/groups/1234)
  }
 }
}

I've seen use of Url.Link() but I've only gotten that to work within my controller - not my url property above. If it can't be done within the POCO, is there a preferred way to update my collection of Group objects after Dapper loads them?

Answer 1

After dapper/service loads the records, you will then need to traverse the collection and generate the URL based on the identifier for the record and the route

Assuming

public class Group {
    public string Name { get; set; }
    public string Url { get; set; }
}

A controller that generates the record URL could follow the following pattern

[Route("v1/groups")]
public class GroupsController : Controller {

    //...omitted for brevity

    //GET v1/groups
    [HttpGet("")]
    public IActionResult Get() {
        IEnumerable<Group> groups = service.GetGroups()
            .Select(group => {            
                var url = Url.RouteUrl("GetGroup", new { name = group.Name });
                group.Url = url;
                return group;
            }).ToList();
        if(!groups.Any()) return NotFound();
        return Ok(groups);
    }

    //GET v1/groups/1234
    [HttpGet("{name}", Name = "GetGroup")]
    public IActionResult Get(string name) {
        var group = service.GetGroup(name);
        if(group == null) return NotFound();
        group.Url = Url.RouteUrl("GetGroup", new { name = group.Name });
        return Ok(group);
    }
}

Reference Generating URLs by route