I have been trying to sort out this for hours and could not find a solution.
I am using a Web Api MVC project and trying to convert an IEnumerable list to a paged list async. I'm able to compile but I'm still getting a runtime error on the ToPagedListAsync() line.
The provider for the source IQueryable doesn't implement IDbAsyncQueryProvider. Only providers that implement IDbAsyncQueryProvider can be used for Entity Framework asynchronous operations. For more details see http://go.microsoft.com/fwlink/?LinkId=287068."
1st Layer:
public async Task<IEnumerable<MatchingCriteria>> GetMatchingCriterias(int id)
{
return await _ctx.MatchingCriterias.Include(mc => mc.RuleDefinition).Where(mc => mc.RuleDefinitionId == id).ToListAsync();
}
2nd Layer:
internal async Task<IEnumerable<MatchingCriteria>> GetMatchingCriterias(int id)
{
using (CrawlerDbContext db = new CrawlerDbContext())
{
var matchCriteriaMgr = new MatchingCriteriaManager(db);
return await matchCriteriaMgr.GetMatchingCriterias(id);
}
}
Controller:
public async Task<ActionResult> Index(int? id, string sortOrder, string currentFilter, string searchString, int? page){
var matchingCriterias = await _crawlerProvider.GetMatchingCriterias(id.Value);
//...
IQueryable<MatchingCriteria> matchCrit = matchingCriterias.AsQueryable();
//Error here -> return View(await matchCrit.ToPagedListAsync(pageNumber, pageSize));
}
if I do instead in the controller:
var matchingCriterias = _db.MatchingCriterias.Include(mc => mc.RuleDefinition);
then:
return View(await matchingCriterias.ToPagedListAsync(pageNumber, pageSize)
That works well!
I could return a DbSet on the nested methods but I could not use the ToListAsync() in the 1st layer;
Is there a way to make the list IQueryable?Any other ideas or suggestions?
Well, I fixed it myself by creating an AsyncQueryable extension as mentioned here
Then I could call the pagedListAsync() method like bellow:
return View(await matchingCriterias.AsAsyncQueryable().ToPagedListAsync(pageNumber, pageSize)
Related
I am trying to call a WebAPI method from Angular 5 like this:
selectClaims(state: DataSourceRequestState):Observable<DataResult>
{
return this.http.get<GridDataResult>(`${this.apiUrl}/SelectClaims?${toDataSourceRequestString(state)}`);
}
Which calls the API method as expected. The API method is:
[Route("SelectClaims")]
[HttpGet]
public IHttpActionResult SelectClaims([FromUri][DataSourceRequest]DataSourceRequest ClaimsRequest)
{
if(ClaimsRequest == null)
ClaimsRequest=new DataSourceRequest { Page=1, PageSize=20 };
var result = _db.Claims.ToDataSourceResult(ClaimsRequest, c => { c.SortHistory(); return c; });
return Ok(result);
}
The trouble is that ClaimsRequest only de-serializes Page and PageSize correctly. Filters and Sorts don't come through:
Fiddler tells me that the URL from Angular is:
GET /api/v1/Claims/SelectClaims?filter=id~eq~2&page=1&sort=firstName-asc&pageSize=20 HTTP/1.1, but in the controller both filter and sort are null.
If I create a URL through Swagger like: 'http://localhost:50223/api/v1/Claims/SelectClaims?ClaimsRequest.page=1&ClaimsRequest.pageSize=11&ClaimsRequest.sorts=firstName-desc' I do see a sort array in the API method, but the "Member" field is null.
Any attempt to add a filter through Swagger like 'http://localhost:50223/api/v1/Claims/SelectClaims?ClaimsRequest.page=1&ClaimsRequest.pageSize=11&ClaimsRequest.filters=id~eq~2' results in a "Cannot create an instance of an interface." error.
The state is a DataSourceRequestState in the angular component from a Kendo Grid for Angular.
I have simulated this in a simple test program and everything works fine there. The only difference in my test program is that the API controller targets .Net Core and the real system targets .Net 4.6.1.
Do I have to de-serialize manually in .Net 4.6.1 for some reason, or is something else going on here?
It should be a POST not a GET. Something like this:
return this.http.post<GridDataResult>(`${this.apiUrl}/SelectClaims`, toDataSourceRequestString(state)});
I needed it to be a GET (URL) so i created a new object
public class GridParamaterBinder
{
public int Page { get; set; }
public int PageSize { get; set; }
public string Filter { get; set; }
public string Sort { get; set; }
public DataSourceRequest ToDataSourceRequest(IConfigurationProvider mapper, Func<string, string> OverDefaultParamaterMapping)
{
DataSourceRequest result = new DataSourceRequest();
result.Page = Page;
result.PageSize = PageSize;
result.Sorts = GridDescriptorSerializer.Deserialize<SortDescriptor>(Sort);
result.Filters = FilterDescriptorFactory.Create(Filter);
return result;
}
}
and used it instead of the Telerik effort.
in API I Bind it like so
public virtual DataSourceResult Get([FromUri]GridParamaterBinder request)
And then used it like
DataSourceResult results = query.ToDataSourceResult(request.ToDataSourceRequest(), r => (r)));
Thanks #KevDevMan for your solution. I found this example,
then I changed my API controller like this and it worked like a charm :
[HttpGet, Route("for-kendo-grid")]
public DataSourceResult GetProducts([System.Web.Http.ModelBinding.ModelBinder(typeof(WebApiDataSourceRequestModelBinder))] DataSourceRequest request)
explanation here
I'm trying to move my web api 2 project to ASP.NET 5.
But I have many elements that are not present anymore.
For example IHttpActionResult or Ok(), NotFound() methods.
Or RoutePrefix[]
Should I change every IHttpActionResult with IActionResult ?
Change Ok() with new ObjectResult ? (is it the same ?)
What about HttpConfiguration that seems no more present in startup.cs ?
IHttpActionResult is now effectively IActionResult, and to return an Ok with a return object, you'd use return new ObjectResult(...);
So effectively something like this:
public IActionResult Get(int id)
{
if (id == 1) return HttpNotFound("not found!");
return new ObjectResult("value: " + id);
}
Here's a good article with more detail:
http://www.asp.net/vnext/overview/aspnet-vnext/create-a-web-api-with-mvc-6
Updated reply-ish
I saw that someone referenced the WebApiCompatShim in a comment.
WebApiCompatShim is still maintained for this kind of portability scenarios and it is now released 1.1.0.
I saw that Microsoft.AspNetCore.OData 1.0.0-rtm-00011 has WebApiCompatShim as a dependency. I don't know exactly what they are trying to achieve in this area, these are just facts.
If you're not into getting another compatibility package and you're looking into more refactoring work, you can look at the following approach: WebApiCompatShim - how to configure for a REST api with MVC 6
You will still be able to use Ok() or you can try to use the OkObjectResult() method as Http word was removed in order not to be too verbose. HttpOkObjectResult -> OkObjectResult
[HttpPost]
public ObjectResult Post([FromBody]string value)
{
var item = new {Name= "test", id=1};
return new OkObjectResult(item);
}
[HttpPost]
public ObjectResult Post([FromBody]string value)
{
var item = new {Name= "test", id=1};
return Ok(item);
}
At 2.2, the ASP.NET Core migration guide states to replace IHttpActionResult with ActionResult. This works for me:
[Produces("application/json")]
[HttpPost]
public ActionResult GetSomeTable([FromBody] GridState state)
{
return Ok(new
{
data = query.ToList(),
paging = new
{
Total = total,
Limit = state.limit,
page = state.page,
Returned = query.Count()
}
});
}
The website that I'm working on is heavily depending on ajax/json and knockout.js.
I would like to have a lot of my Controllers return view-tailored 'json objects', without wrapping them in a JsonResult when returning the method.
This would mean I could easily composite multiple calls into one parent object, but still be able to call the Actions separately too.
Simplified example:
public object Main(int groupId)
{
var viewModel = new
{
Persons = Employees(groupId),
Messages = AllMessages()
};
return viewModel;
}
public object Employees(int groupId)
{
return DatabaseContext.Employees.Where(e => e.GroupId == groupId).ToList();
}
public object AllMessages()
{
return DatabaseContext.Messages.ToList();
}
I was hoping I could capture the returned object in OnActionExecuted and at that point wrap the whole result up in a final JsonResult.
The result is already converted to a string and captured in a ContentResult though.
Any ideas? :) Thanks,
A good approach on this is to create helper methods for your entity calls. Or if you have those methods already somewhere, they can actually serve as the helper methods. In that manner you can return a list of strongly-typed Messages and Employees as well as returning your desired parent object. You can then have individual controller methods that returns json objects. In addition, you can extend the parent viewmodel to return additional fields.
The Parent ViewModel
public class ParentModel {
public Employee Persons {get;set;}
public Message Messages {get;set;}
}
The Helper Methods
The beauty of using helper methods similar to what is defined here is that you can apply a few more logic to your query, and more, and you don't have to change anything in your controller methods.
public ParentModel GetMain(int groupId)
{
var viewModel = new ParentModel
{
Persons = Employees(groupId),
Messages = AllMessages()
};
return viewModel;
}
public IEnumerable<Employee> Employees(int groupId)
{
return DatabaseContext.Employees.Where(e => e.GroupId == groupId).ToList();
}
public IEnumerable<Message> AllMessages()
{
return DatabaseContext.Messages.ToList();
}
The Controller Methods
public ActionResult GetParent(int groupId){
return Json(helperinstance.GetMain());
}
public ActionResult GetEmployees(int groupId){
return Json(helperinstance.Employees());
}
public ActionResult GetMessages(int groupId){
return Json(helperinstance.AllMessages());
}
Thanks for the answer. I'm not going for the solution of von v. because I like to keep the boilerplate as small as possible.
In the end I am trying out the following approach. It seems to work pretty well for now, but I still have to test it in real production.
If anyone has some (security) concerns with this, I'm happy to hear them in the comments.
// BaseController
protected override void OnActionExecuting(ActionExecutingContext filterContext)
{
var returnType = ((ReflectedActionDescriptor)filterContext.ActionDescriptor).MethodInfo.ReturnType;
// is the returnType not deriving from ActionResult? Automatically wrap it in a JsonResult
if ( !typeof(ActionResult).IsAssignableFrom(returnType) )
{
var result = filterContext.ActionDescriptor.Execute(filterContext, filterContext.ActionParameters);
filterContext.Result = Json( result );
}
}
i have the following model method inside my asp.net MVc web application:-
public IQueryable<User> searchusers(string q, int id)
{
return from u in entities1.Users
where (!u.Users_Classes.Any(c => c.ClassID == id) && (u.UserID.Contains(q))
select u;
}
which will be called using the following action method:-
[AcceptVerbs(HttpVerbs.Post)]
public PartialViewResult Search(string q, int classid)
{
var users = r.searchusers(q, classid).ToList();
ViewBag.id = classid;
// code does here
}
now if i remove the .ToList() from my action method the code will still work fine,, so will using the .ToList() method bring any advantages or features ?
BR
Edit:-
here is the full code for my action method:-
[AcceptVerbs(HttpVerbs.Post)]
public PartialViewResult Search(string q, int classid)
{
var users = r.searchusers(q, classid).ToList();
ViewBag.id = classid;
return PartialView("_usersearch", users);
}
When you call ToList, you ask the Entity Framework to execute the query immediately, and then you will work with in memory collection. Otherwise, the query will be executed when you loop through the result.
I have been fighting with this all day and still I am failing.
I can simplify the problem as follows:
I have reports and reports have forms. I have entity models of each. They have Guid id's as shown below.
I am trying to get a single view where I can create a report and a form. As an end goal I would like to be able to add multiple forms, but just one would be great. My controller is as follows:
// GET: /AllInOne/Create
public ActionResult Create()
{
ViewBag.PossibleReportBases = reportBaseRepository.All;
ViewBag.PossibleCategories = categoryRepository.All;
var model = new Report {FromDate = DateTime.Now};
model.Forms.Add(new Form());
return View(model);
}
// POST: /AllInOne/Create
[HttpPost]
public ActionResult Create(Report report)
{
if (ModelState.IsValid) {
reportRepository.InsertOrUpdate(report);
reportRepository.Save();
return RedirectToAction("Index");
}
else
{
ViewBag.PossibleReportBases = reportBaseRepository.All;
ViewBag.PossibleCategories = categoryRepository.All;
return View();
}
}
The repository code looks like this:
public void InsertOrUpdate(Report report)
{
if (report.Id == default(System.Guid)) {
// New entity
report.Id = Guid.NewGuid();
context.Reports.AddObject(report);
} else {
// Existing entity
context.Reports.Attach(report);
context.ObjectStateManager.ChangeObjectState(report, EntityState.Modified);
}
}
At one stage the binding was giving me this error:
The EntityCollection has already been initialized. The InitializeRelatedCollection method should only be called to initialize a new EntityCollection during deserialization of an object graph.
I have tried many things for the views, but none of them have worked.
Please help.
i dont' think you need to bother with the attaching. if you've selected the report from your context, it is already being tracked. you can simplify your repository like so
public void InsertOrUpdate(Report report)
{
// i prefer Guid.Empty but no big deal
if (report.Id == default(System.Guid)) {
// New entity
report.Id = Guid.NewGuid();
context.Reports.AddObject(report);
}
context.SaveChanges();
}