I have a ASP .Net Core MVC app where I have a table in a view that is being populated by data from an entity framework query. Following this guide, I've implemented code to paginate the table. For some reason, when the request for the table data is sent from the client side to controller action, there is the following error:
InvalidOperationException: The provider for the source IQueryable doesn't implement IAsyncQueryProvider. Only providers that implement IEntityQueryProvider can be used for Entity Framework asynchronous operations.
Here is the controller action:
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> GetResultList(ResortDataJoinObj resDeals, int page =1)
{
if (ModelState.IsValid)
{
var resultsObj = (from rd in _db.ResortData
join ra in _db.ResortAvailability on rd.RecNo equals ra.RecNoDate
where ra.TotalPrice < Int32.Parse(resDeals.priceHighEnd) && ra.TotalPrice > Int32.Parse(resDeals.priceLowEnd)
select new
{
Name = rd.Name,
ImageUrl = rd.ImageUrl,
ResortDetails = rd.ResortDetails,
CheckIn = ra.CheckIn,
Address = rd.Address,
TotalPrice = ra.TotalPrice
});
int i = 0;
List<ResortDealResultsObject> resultList = new List<ResortDealResultsObject>();
foreach (var row in resultsObj)
{
var tempVm = new ResortDealResultsObject
{
Name = row.Name,
ImageUrl = row.ImageUrl,
ResortDetails = row.ResortDetails,
CheckIn = row.CheckIn,
Address = row.Address,
TotalPrice = row.TotalPrice
};
resultList.Add(tempVm);
}
int pageSize = 3;
var model = await PaginatedList<ResortDealResultsObject>.CreateAsync(resultList.AsQueryable(), page, pageSize);
ResortDataJoinObj joinObj = new ResortDataJoinObj();
joinObj.PageList = model;
ViewBag.rowsReturned = true;
return View(joinObj);
}
return View(resDeals);
}
It looks like the error is being caused by the line var model = await PaginatedList<ResortDealResultsObject>.CreateAsync(resultList.AsQueryable(), page, pageSize);
This line is calling a method within the class PaginatedList, which is implemented in its own file (as outlined in the guide):
public static async Task<PaginatedList<T>> CreateAsync(IQueryable<T> source, int pageIndex, int pageSize)
{
var count = await source.CountAsync();
var items = await source.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToListAsync();
return new PaginatedList<T>(items, count, pageIndex, pageSize);
}
There are no pre-compiler or compilation errors so I'm not sure exactly what is wrong here since I'm following the guide pretty closely. What could be causing the error?
List<ResortDealResultsObject> resultList = new List<ResortDealResultsObject>();
foreach (var row in resultsObj)
{
var tempVm = new ResortDealResultsObject
{
Name = row.Name,
ImageUrl = row.ImageUrl,
ResortDetails = row.ResortDetails,
CheckIn = row.CheckIn,
Address = row.Address,
TotalPrice = row.TotalPrice
};
resultList.Add(tempVm);
}
This code is not generated by entity framework and does not provide asynchronious calls.
You already have a List when you call the ToListAsync() method so there is no point to cast it to a Queryable and call ToListAsync() on it
The following code should do the work
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> GetResultList(ResortDataJoinObj resDeals, int page =1)
{
if (ModelState.IsValid)
{
var resultsObj = from rd in _db.ResortData
join ra in _db.ResortAvailability on rd.RecNo equals ra.RecNoDate
where ra.TotalPrice < Int32.Parse(resDeals.priceHighEnd) && ra.TotalPrice > Int32.Parse(resDeals.priceLowEnd)
select new ResortDealResultsObject
{
Name = rd.Name,
ImageUrl = rd.ImageUrl,
ResortDetails = rd.ResortDetails,
CheckIn = rd.CheckIn,
Address = rd.Address,
TotalPrice = rd.TotalPrice
};
int pageSize = 3;
var model = await PaginatedList<ResortDealResultsObject>.CreateAsync(resultsObj, page, pageSize);
ResortDataJoinObj joinObj = new ResortDataJoinObj();
joinObj.PageList = model;
ViewBag.rowsReturned = true;
return View(joinObj);
}
return View(resDeals);
}
I didn't test it so there could be some compile time errors but the logic is there :)
Related
I have a document table here is my query how can I sum the documents that I now have in sql and display in viewmodel by linq in asp.net core 3.1
public async Task<PagedResult<DocumentsVm>> GetTotal(GetDocumentsPagingRequest request)
{
var query = from d in _context.Documents //This is my query
join u in _context.Users on d.UserID equals u.Id
select new { d, u };
int TotalRow = await query.CountAsync();
var data = await query.Skip((request.PageIndex - 1) * request.PageSize)
.Take(request.PageSize)
.Select(x => new DocumentsVm()
{
ID = x.d.ID,
Caption = x.d.Caption,
FacultyID = x.d.FacultyOfDocumentID,
Status = x.d.Status,
CreateOn = x.d.CreateOn.Date,
ViewCount = ??? //I want to display total document here
}).ToListAsync();
var pagedResult = new PagedResult<DocumentsVm>()
{
TotalRecord = TotalRow,
Items = data
};
return pagedResult;
}
So I'm trying to use a DTO to reshape and return data, it's not working because I'm trying to push in an array of objects (as an IQueryable - which I don't think works) into the DTO, I'm also trying to push in dynamic data into one of the properties, as seen below in the 'hasCurrentUserLiked' property. I need to figure out How to change the objects from IQueryable, into actual objects so they can all be pushed into the DTO and the dynamic data can be worked out.
This is the code
public async Task<PagedList<UserPhoto>> GetSpecificFeed(UserParams userParams)
{
var user = _context.Users.FirstOrDefault(x => x.Username == userParams.u);
var userId = user.Id;
var photos = _context.UserPhotos;
var followerIds = _context.Follows.Where(x => x.FollowerId == userId).Select(x => x.FollowingId).ToList();
var feeds = _context.UserPhotos.Where(x => followerIds.Contains(x.UserId)).OrderByDescending(x => x.DateAdded);
// this doesn't work because 'feeds' is an IQueryable, not an object
var like = await hasCurrentUserLiked(user.Id, feeds.id);
// this has the same problem as above
var feedsToReturn = new FeedsForReturnDto
{
Id = feeds.Id,
PhotoUrl = feeds.photoUrl,
Username = feeds.Username,
Description = feeds.Description,
DateAdded = feeds.DateAdded,
IsImage = feeds.IsImage,
hasCurrentUserLiked = like,
Likes = feeds.Likes
}
return await PagedList<UserPhoto>.CreateAsync(feedsToReturn, userParams.PageNumber, userParams.PageSize);
}
I thought that I might be able to get each image.id in a similar way the 'followerIds' are worked out but I couldn't figure out how to get this to work
[EDIT]
As per Enas Osamas answer, I've changed the code to this and I've debugged it, feedsToReturn has the correct info, so it is doing what its supposed to do. The problem I'm having now is that I'm unable to return it as it can't convert the IEnumerable to an IQueryable. I tried adding an explicit cast but that didn't work, I also tried removing the PagedList, and replacing the type to but this didn't work. My is an IQueryable which might be the problem, I tried changing that to an IEnumerable but this would mess up the code in other places.
This is my new code (still returning 'feeds' instead of 'feedsToReturn', will change when it works)
public async Task<PagedList<UserPhoto>> GetSpecificFeed(UserParams userParams)
{
var user = _context.Users.FirstOrDefault(x => x.Username == userParams.u);
var userId = user.Id;
var photos = _context.UserPhotos;
var followerIds = _context.Follows.Where(x => x.FollowerId == userId).Select(x => x.FollowingId).ToList();
var feeds = _context.UserPhotos.Where(x => followerIds.Contains(x.UserId)).OrderByDescending(x => x.DateAdded);
var feedToReturn = feeds.AsEnumerable().Select(feed => new FeedsForReturnDto
{
Id = feed.Id,
PhotoUrl = feed.photoUrl,
Username = feed.Username,
Description = feed.Description,
DateAdded = feed.DateAdded,
IsImage = feed.IsImage,
hasCurrentUserLiked = hasCurrentUserLiked(user.Id, feed.Id),
Likes = feed.Likes
});
return await PagedList<UserPhoto>.CreateAsync(feeds, userParams.PageNumber, userParams.PageSize);
}
I also tried changing some of the types around and this is what I came up with. The problem here is this:
'System.Collections.Generic.IEnumerable<cartalk.api.Dtos.feeds.FeedsForReturnDto>' to 'System.Linq.IQueryable<System.Collections.IEnumerable>'
and this problem is with the 'feedsToReturn' in the last line
public async Task<PagedList<IEnumerable>> GetSpecificFeed(UserParams userParams)
{
var user = _context.Users.FirstOrDefault(x => x.Username == userParams.u);
var userId = user.Id;
var photos = _context.UserPhotos;
var followerIds = _context.Follows.Where(x => x.FollowerId == userId).Select(x => x.FollowingId).ToList();
var feeds = _context.UserPhotos.Where(x => followerIds.Contains(x.UserId)).OrderByDescending(x => x.DateAdded);
var feedToReturn = feeds.AsEnumerable().Select(feed => new FeedsForReturnDto
{
Id = feed.Id,
PhotoUrl = feed.photoUrl,
Username = feed.Username,
Description = feed.Description,
DateAdded = feed.DateAdded,
IsImage = feed.IsImage,
hasCurrentUserLiked = hasCurrentUserLiked(user.Id, feed.Id),
Likes = feed.Likes
});
return await PagedList<IEnumerable>.CreateAsync(feedToReturn, userParams.PageNumber, userParams.PageSize);
}
PagedList code
public static async Task<PagedList<T>> CreateAsync(IQueryable<T> source,
int pageNumber, int pageSize)
{
var count = await source.CountAsync();
var items = await source.Skip((pageNumber - 1) * pageSize).Take(pageSize).ToListAsync();
return new PagedList<T>(items, count, pageNumber, pageSize);
}
[EDIT]
This is the hasCurrentUserLiked function, it works here
public bool checkCurrentUserLiked(int currentUserId, int imageId)
{
var doesCurrentUserLike = _context.PhotoLikes.Where(x => x.LikerId == currentUserId && x.ImageId == imageId);
var value = true;
if (doesCurrentUserLike == null)
{
value = false;
}
else
{
value = true;
}
return value;
}
You can try something like
feeds.AsEnumerable().Select(feed => new FeedsForReturnDto
{
Id = feed.Id,
PhotoUrl = feed.photoUrl,
Username = feed.Username,
Description = feed.Description,
DateAdded = feed.DateAdded,
IsImage = feed.IsImage,
hasCurrentUserLiked = hasCurrentUserLiked(user.Id, feed.id),
Likes = feed.Likes
});
This would return an IEnumerable containing all the feeds mapped to your DTO after being enumerated to avoid performing operations against the database
[EDIT]
you can maybe do a left join with the _context.PhotoLikes.
Like this
feeds.GroupJoin(_context.PhotoLikes,
f => new { Id = f.Id, UserId = user.Id },
p => new { Id = p.ImageId, UserId = p.LikerId },
(f, p) => new { feed = f, photoLike = p })
.SelectMany(f => f.photoLike.DefaultIfEmpty(),
(f, p) => new FeedsForReturnDto
{
Id = f.feed.Id,
PhotoUrl = f.feed.photoUrl,
Username = f.feed.Username,
Description = f.feed.Description,
DateAdded = f.feed.DateAdded,
IsImage = f.feed.IsImage,
hasCurrentUserLiked = p != null,
Likes = feed.Likes
});
Just note that in this part
f => new { Id = f.Id, UserId = user.Id },
p => new { Id = p.ImageId, UserId = p.LikerId },
the datatypes of properties in both objects must match or it won't compile
I have following methods:
Controller:
...
var appmap = Services.GetReqAppMapList(value);
var applist = Services.GetApplicationList(docid, appid, reqid, appmap);
...
Model:
public static IEnumerable<AppMap> GetReqAppMapList(int aiRequestTypeId)
{
try
{
var appmap = new List<AppMap>();
using (var eties = new eRequestsEntities())
{
appmap = (from ram in eties.ReqAppMaps
where ram.IsActive == 1
select new AppMap
{
RequestTypeId = ram.RequestTypeId
}).ToList();
return appmap;
}
}
catch(Exception e)
{
throw e;
}
}
public static IEnumerable<TicketApplication> GetApplicationList(int aiDocumentTypeId, int aiApplicationTypeId, int aiRequestTypeId, IEnumerable<AppMap> appmap)
{
try
{
var applicationlist = new List<TicketApplication>();
using (var applicationentity = new eRequestsEntities())
{
applicationlist = (from app in applicationentity.Applications
where 1==1
<<<Some Conditions Here???>>>
== && appmap.Contains(app.ApplicationTypeId) ==
&& app.IsActive == 1
select new TicketApplication
{
ApplicationId = app.ApplicationId,
Description = app.Description,
DeliveryGroupId = app.DeliveryGroupId,
ApplicationTypeId = app.ApplicationTypeId,
DeliveryTypeId = app.DeliveryTypeId,
DocumentTypeId = app.DocumentTypeId,
SupportGroupId = app.SupportGroupId
}).OrderBy(a => a.Description).ToList();
return applicationlist;
}
And I was thinking how can filter query result of GetApplicationList using the result from GetReqAppMapList
I'm kinda stuck with the fact that I must convert/cast something to the correct type because every time I do a result.Contains (appmap.Contains to be exact), I always get the following error
Error 4 Instance argument: cannot convert from
'System.Collections.Generic.IEnumerable<Test.Models.AppMap>' to
'System.Linq.ParallelQuery<int?>'
You should directly join the two tables in one query.
using (var applicationentity = new eRequestsEntities())
{
applicationlist = (from app in applicationentity.Applications
join ram in applicationentity.ReqAppMaps on app.ApplicationTypeId equals ram.RequestTypeId
where ram.IsActive == 1 && app.IsActive == 1
select new TicketApplication
{
ApplicationId = app.ApplicationId,
Description = app.Description,
DeliveryGroupId = app.DeliveryGroupId,
ApplicationTypeId = app.ApplicationTypeId,
DeliveryTypeId = app.DeliveryTypeId,
DocumentTypeId = app.DocumentTypeId,
SupportGroupId = app.SupportGroupId
}).OrderBy(a => a.Description).ToList();
You can delete the other method if it is not needed anymore. No point hanging onto code which is dead.
Looks like there is no other way to do this (as far as I know), so I have to refactor the code, I hope still that there would be a straight forward conversion and matching method in the future (too lazy). Anyway, please see below for my solution. Hope this helps someone with the same problem in the future. I'm not sure about the performance, but this should work for now.
Controller:
...
var appmap = Services.GetReqAppMapList(value);
var applist = Services.GetApplicationList(docid, appid, reqid, appmap);
...
Model:
<Removed GetReqAppMapList>--bad idea
public static IEnumerable<TicketApplication> GetApplicationList(int aiDocumentTypeId, int aiApplicationTypeId, int aiRequestTypeId)
{
try
{
//This is the magic potion...
List<int?> appmap = new List<int?>();
var applist = (from ram in applicationentity.ReqAppMaps
where ram.RequestTypeId == aiRequestTypeId
&& ram.IsActive == 1
select new AppMap
{
ApplicationTypeId = ram.ApplicationTypeId
}).ToList();
foreach (var item in applist)
{
appmap.Add(item.ApplicationTypeId);
}
//magic potion end
var applicationlist = new List<TicketApplication>();
using (var applicationentity = new eRequestsEntities())
{
applicationlist = (from app in applicationentity.Applications
where 1==1
===>>>&& appmap.Contains(app.ApplicationTypeId)<<<===
&& app.IsActive == 1
select new TicketApplication
{
ApplicationId = app.ApplicationId,
Description = app.Description,
DeliveryGroupId = app.DeliveryGroupId,
ApplicationTypeId =app.ApplicationTypeId,
DeliveryTypeId = app.DeliveryTypeId,
DocumentTypeId = app.DocumentTypeId,
SupportGroupId = app.SupportGroupId
}).OrderBy(a => a.Description).ToList();
return applicationlist;
}
A side-note, C# is a strongly-typed language, just make sure your data types matches during evaluation, as int? vs int etc.., will never compile. A small dose of LINQ is enough to send some newbies circling around for hours. One of my ID-10T programming experience but just enough to remind me that my feet's still flat on the ground.
I have a problem with LINQ query (see comment) there is a First method and it only shows me the first element.
When I write in the console "Sales Representative" it shows me only the first element of it as in
I would like to get all of data about Sales Representative. How can I do it?
public PracownikDane GetPracownik(string imie)
{
PracownikDane pracownikDane = null;
using (NORTHWNDEntities database = new NORTHWNDEntities())
{
//Employee matchingProduct = database.Employees.First(p => p.Title == imie);
var query = from pros in database.Employees
where pros.Title == imie
select pros;
// Here
Employee pp = query.First();
pracownikDane = new PracownikDane();
pracownikDane.Tytul = pp.Title;
pracownikDane.Imie = pp.FirstName;
pracownikDane.Nazwisko = pp.LastName;
pracownikDane.Kraj = pp.Country;
pracownikDane.Miasto = pp.City;
pracownikDane.Adres = pp.Address;
pracownikDane.Telefon = pp.HomePhone;
pracownikDane.WWW = pp.PhotoPath;
}
return pracownikDane;
}
Right now you are just getting the .First() result from the Query collection:
Employee pp = query.First();
If you want to list all employees you need to iterate through the entire collection.
Now, if you want to return all the employee's you should then store each new "pracownikDane" you create in some sort of IEnumerable
public IEnumerable<PracownikDane> GetPracownik(string imie) {
using (NORTHWNDEntities database = new NORTHWNDEntities())
{
var query = from pros in database.Employees
where pros.Title == imie
select pros;
var EmployeeList = new IEnumerable<PracownikDane>();
foreach(var pp in query)
{
EmployeeList.Add(new PracownikDane()
{
Tytul = pp.Title,
Imie = pp.FirstName,
Nazwisko = pp.LastName,
Kraj = pp.Country,
Miasto = pp.City,
Adres = pp.Address,
Telefon = pp.HomePhone,
WWW = pp.PhotoPath
});
}
return EmployeeList;
}
Then, with this returned List you can then do what ever you wanted with them.
I want to use one action into another action for getting some values as:
[HttpPost]
public ActionResult Playlist(PageInfo p, long ID)
{
//long playid=Convert.ToInt64(p.Where);
var q = from client in my.Clients(0, 0)
join pl in db.Playlists on client.ClientId equals pl.ClientId
select new SimpleViewModel
{
Sequence=pl.PlaylistContentSequenceId,
PlaylistID = pl.PlaylistId,
PlaylistContentID=pl.ContentId
};
return Json(q.ToPage(p, "Sequence"), JsonRequestBehavior.DenyGet);
}
[HttpPost]
public ActionResult Save(List<ItemEditViewModel> data,long playlistid, List<long> deleted,string Title)
{
var playlist = db.Playlists.Include("PlaylistContents").FirstOrDefault(x => x.PlaylistId == playlistid);
for (int i = 0; i < playlist.PlaylistContents.Count; i++)
{
if(deleted.IndexOf(playlist.PlaylistContents[i].PlaylistContentId)>-1){
playlist.PlaylistContents.Remove(playlist.PlaylistContents[i]);
}
}
db.SaveChanges();
long ID=playlistid;
return Playlist(new PageInfo(),ID);
}
as you have seen in the code that after saving the contents into the database, the Playlist controller should be used for returning the Json data.
instead of
return Playlist(new PageInfo(),ID);
try
return RedirectToAction("Playlist", new {p = new PageInfo(), ID = ID});