How to get associated name of linked resources in HAL - asp.net-web-api

Question

I am creating an API for project tasks. It has a TasksController as listed below. I am generating hypermedia using WebApi.Hal and the service supports hal+json and hal+xml media types also.
Following is the response I currently have for the GET request http://localhost:51910/api/tasks/1. In the response there is a list of links for priorities – but they don’t have associated name in the response (to show in the UI – like Low, Medium, High, etc.).
What is the best HAL approach for getting name of the priorities also, using WebApi.HAL?
Note: The list of priorities can be enhanced in the future.
Priority
public class Priority
{
public int PriorityID { get; set; }
public string PriorityName { get; set; }
public string Revision { get; set; }
public DateTime ApprovalDate { get; set; }
}
Controller
public class TasksController : ApiController
{
// GET api/values/5
[HttpGet]
public TaskRepresentation Get(int id)
{
Task selectedTask = TasksHelper.GetTask(id);
TaskRepresentation taskRepresentation = new TaskRepresentation(selectedTask);
return taskRepresentation;
}
//PUT For Setting Priority
[HttpPut]
[Route("api/tasks/{taskID}/priorities/{priorityID}")]
public TaskRepresentation PutSetPriority(int taskID, int priorityID)
{
Task selectedTask = TasksHelper.GetTask(taskID);
Priority selectedPriority = null;
List<Priority> allPriorities = TasksPrioritiesHelper.GetAllPriorities();
foreach (Priority p in allPriorities)
{
if (p.PriorityID == priorityID)
{
selectedPriority = p;
}
}
//Update Task
if (selectedPriority != null)
{
selectedTask.CurrentPriority = selectedPriority.PriorityName;
}
else
{
throw new Exception("Not available");
}
TaskRepresentation taskRepresentation = new TaskRepresentation(selectedTask);
return taskRepresentation;
}
[HttpGet]
[Route("api/tasks/{taskID}/priorities/{priorityID}")]
public Priority Get(int taskID, int priorityID)
{
Priority selectedPriority = null;
List<Priority> allPriorities = TasksPrioritiesHelper.GetAllPriorities();
foreach (Priority p in allPriorities)
{
if (p.PriorityID == priorityID)
{
selectedPriority = p;
}
}
return selectedPriority;
}
}
HAL Generation Related Classes
public static class LinkTemplates
{
public static class TaskLinks
{
public static Link TaskEntry { get { return new Link("self", "~/api/tasks/{taskID}"); } }
public static Link PriorityLink { get { return new Link("priorities", "~/api/tasks/{taskID}/priorities/{priorityID}"); } }
}
}
public class TaskRepresentation : Representation
{
Task theTask;
public int TaskID{get{return theTask.TaskID;}}
public string TaskName{get{return theTask.Name;}}
public string CurrentPriority{get{return theTask.CurrentPriority;}}
public string Category{get{return theTask.Category;}}
public TaskRepresentation(Task t)
{
theTask = t;
}
public override string Rel
{
get { return LinkTemplates.TaskLinks.TaskEntry.Rel; }
set { }
}
public override string Href
{
get { return LinkTemplates.TaskLinks.TaskEntry.CreateLink(new { taskID = theTask.TaskID }).Href; }
set { }
}
protected override void CreateHypermedia()
{
foreach (Priority p in theTask.PossiblePriorities)
{
Links.Add(LinkTemplates.TaskLinks.PriorityLink.CreateLink(new { taskID = theTask.TaskID, priorityID = p.PriorityID }));
}
}
}

Answer 1

HAL Specification mentions title - this will meet the requirement.
Following is the updated response.
{
"TaskID": 1,
"TaskName": "Task1",
"CurrentPriority": "Medium",
"Category": "IT",
"_links": {
"self": {
"href": "/api/tasks/1"
},
"priorities": [
{
"href": "/api/tasks/1/priorities/101",
"title": "Low"
},
{
"href": "/api/tasks/1/priorities/103",
"title": "High"
},
{
"href": "/api/tasks/1/priorities/104",
"title": "Critical"
}
]
}
}
WebAPI.HAL changes
protected override void CreateHypermedia()
{
foreach (Priority p in theTask.PossiblePriorities)
{
Link lnk = LinkTemplates.TaskLinks.PriorityLink.CreateLink(new { taskID = theTask.TaskID, priorityID = p.PriorityID });
lnk.Title = p.PriorityName;
Links.Add(lnk);
}
}
Code
public static class LinkTemplates
{
public static class TaskLinks
{
public static Link TaskEntry { get { return new Link("self", "~/api/tasks/{taskID}"); } }
//public static Link PriorityLink { get { return new Link("priorities", "~/api/tasks/{taskID}/priorities/{priorityID}"); } }
public static Link PriorityLink
{
get
{
Link l = new Link("priorities", "~/api/tasks/{taskID}/priorities/{priorityID}");
return l;
}
}
}
}
public class TasksController : ApiController
{
// GET api/values/5
[HttpGet]
public TaskRepresentation Get(int id)
{
Task selectedTask = TasksHelper.GetTask(id);
TaskRepresentation taskRepresentation = new TaskRepresentation(selectedTask);
return taskRepresentation;
}
//PUT For Setting Priority
[HttpPut]
[Route("api/tasks/{taskID}/priorities/{priorityID}")]
public TaskRepresentation PutSetPriority(int taskID, int priorityID)
{
Task selectedTask = TasksHelper.GetTask(taskID);
Priority selectedPriority = null;
List<Priority> allPriorities = TasksPrioritiesHelper.GetAllPriorities();
foreach (Priority p in allPriorities)
{
if (p.PriorityID == priorityID)
{
selectedPriority = p;
}
}
//Update Task
if (selectedPriority != null)
{
selectedTask.CurrentPriority = selectedPriority.PriorityName;
}
else
{
throw new Exception("Not available");
}
TaskRepresentation taskRepresentation = new TaskRepresentation(selectedTask);
return taskRepresentation;
}
[HttpGet]
[Route("api/tasks/{taskID}/priorities/{priorityID}")]
public Priority Get(int taskID, int priorityID)
{
Priority selectedPriority = null;
List<Priority> allPriorities = TasksPrioritiesHelper.GetAllPriorities();
foreach (Priority p in allPriorities)
{
if (p.PriorityID == priorityID)
{
selectedPriority = p;
}
}
return selectedPriority;
}
}
public class TaskRepresentation : Representation
{
Task theTask;
public int TaskID{get{return theTask.TaskID;}}
public string TaskName{get{return theTask.Name;}}
public string CurrentPriority{get{return theTask.CurrentPriority;}}
public string Category{get{return theTask.Category;}}
public TaskRepresentation(Task t)
{
theTask = t;
}
public override string Rel
{
get { return LinkTemplates.TaskLinks.TaskEntry.Rel; }
set { }
}
public override string Href
{
get { return LinkTemplates.TaskLinks.TaskEntry.CreateLink(new { taskID = theTask.TaskID }).Href; }
set { }
}
protected override void CreateHypermedia()
{
foreach (Priority p in theTask.PossiblePriorities)
{
Link lnk = LinkTemplates.TaskLinks.PriorityLink.CreateLink(new { taskID = theTask.TaskID, priorityID = p.PriorityID });
lnk.Title = p.PriorityName;
Links.Add(lnk);
}
}
}
public class Task
{
public string Name { get; set; }
public int TaskID { get; set; }
public string Category { get; set; }
public string CurrentPriority { get; set; }
public List<Priority> PossiblePriorities { get; set; }
}
public class Priority
{
public int PriorityID { get; set; }
public string PriorityName { get; set; }
public string Revision { get; set; }
public DateTime ApprovalDate { get; set; }
}
public static class TasksPrioritiesHelper
{
public static List<Priority> GetAllPriorities()
{
List<Priority> possiblePriorities = new List<Priority>();
Priority pLow = new Priority { PriorityID = 101, PriorityName = "Low" };
Priority pMedium = new Priority { PriorityID = 102, PriorityName = "Medium" };
Priority pHigh = new Priority { PriorityID = 103, PriorityName = "High" };
Priority pCritical = new Priority { PriorityID = 104, PriorityName = "Critical" };
possiblePriorities.Add(pLow);
possiblePriorities.Add(pMedium);
possiblePriorities.Add(pHigh);
possiblePriorities.Add(pCritical);
return possiblePriorities;
}
public static List<Priority> GetAdministrativePriorities()
{
List<Priority> possiblePriorities = new List<Priority>();
Priority pLow = new Priority { PriorityID = 101, PriorityName = "Low" };
Priority pHigh = new Priority { PriorityID = 103, PriorityName = "High" };
possiblePriorities.Add(pLow);
possiblePriorities.Add(pHigh);
return possiblePriorities;
}
public static List<Priority> GetPossiblePrioritiesForTask(Task t)
{
List<Priority> possibleTaskPriorities = new List<Priority>();
if (String.Equals(t.Category, "IT"))
{
possibleTaskPriorities = GetAllPriorities();
}
else
{
possibleTaskPriorities = GetAdministrativePriorities();
}
Priority currentTaskPriority = null;
foreach(Priority p in possibleTaskPriorities )
{
if(String.Equals(t.CurrentPriority,p.PriorityName ))
{
currentTaskPriority=p;
}
}
if(currentTaskPriority!=null)
{
possibleTaskPriorities.Remove(currentTaskPriority);
}
return possibleTaskPriorities;
}
}
public static class TasksHelper
{
public static Task GetTask(int id)
{
Task selectedTask = null;
List<Task> tasks = GetAllTasks();
foreach (Task t in tasks)
{
if(t.TaskID==id)
{
selectedTask = t;
}
}
return selectedTask;
}
public static List<Task> GetAllTasks()
{
List<Task> tasks;
tasks = new List<Task>();
Task t1 = new Task{Category = "IT",CurrentPriority = "Medium",Name = "Task1",TaskID = 1};
t1.PossiblePriorities = TasksPrioritiesHelper.GetPossiblePrioritiesForTask(t1);
tasks.Add(t1);
return tasks;
}
}