I was able to get this to work after much frustration, but I was hoping someone could explain to me why this works:
var monthCharges = WRVUData.AsEnumerable()
.Where(dr => dr.Field<DateTime>("Posting_Month") == new DateTime(month.Year, i, 1))
.Where(dr => dr.Field<string>("Report_Producer_Name") == provider || dr.Field<string>("Group_Name") == group)
.Where(dr => dr.Field<decimal?>("Charges") != null)
.Sum(dr => dr.Field<decimal>("Charges"));
but this doesn't:
var monthCharges = (from r in WRVUData.AsDataView()
select new
{
charges = r.Field<decimal?>("Charges"),
activityType = r.Field<string>("Activity_Type"),
postingMonth = r.Field<DateTime>("Posting_Month"),
provider = r.Field<string>("Report_Producer_Name"),
groupName = r.Field<string>("Group_Name"),
WRVUs = r.Field<decimal>("W_RVUs")
})
.Where(dr => dr.postingMonth == new DateTime(month.Year, i, 1))
.Where(dr => dr.provider == provider || dr.groupName == group)
.Where(dr => dr.charges != null)
.Sum(dr => dr.charges);
The second version throws a "Specified cast is not valid" error. Aren't the two basically the same thing?
Related
I have 2 DbContexts in my application, and need to do a join in 2 tables that are each one in a different DbContext; I get this error
value cannot be null. parameter name entitytype
When I try to join 2 tables of the same context, this error does not happen.
var VerificaExistenciaSinistro = sinistroContext.SnsAviso
.Join(
sinistroContext.SnsNumAviso,
sinistro => sinistro.NumApo,
aviso => aviso.NumApo,
(sinistro, aviso) => new {
sinistroV = sinistro,
avisoV = aviso })
.Where(c => c.sinistroV.CodItm == c.avisoV.CodItm &&
c.sinistroV.NumApo == c.avisoV.NumApo &&
c.sinistroV.NumAvs == c.avisoV.SeqNumAvs)
.Join(sgsContext.EmsEmissao,
sinistro1 => sinistro1.sinistroV.CodCtrtAvs,
emissao => emissao.CodCtrt,
(sinistro1, emissao) => new {
sinistroC = sinistro1,
emissaoC = emissao })
.Where(c => c.sinistroC.sinistroV.CodCtrtAvs == c.emissaoC.CodCtrt &&
c.emissaoC.CodEmis == c.sinistroC.avisoV.CodEms)
.Where(x => x.sinistroC.sinistroV.NumApo == apolice &&
x.emissaoC.StsEmis == emissao &&
x.emissaoC.NumEndosso ==endosso &&
x.sinistroC.sinistroV.CodItm == cod_itm &&
x.sinistroC.sinistroV.CodCbe == cbeCod)
.Select(x => x.sinistroC)
.ToList();
It generally occurs when u query data from two dbcontext using IQueryable
I encountered the same issue when I was using two dbContext. The solution which I found was. If u are using join between two tables then load any one table's data first to a variable/Object so that It becomes IEnumerable or IList and then do join with that variable/Object to the another table of another dbContext
Example
var FirstDbContextTable = sinistroContext.SnsAviso
.Join(
sinistroContext.SnsNumAviso,
sinistro => sinistro.NumApo,
aviso => aviso.NumApo,
(sinistro, aviso) => new {
sinistroV = sinistro,
avisoV = aviso })
.Where(c => c.sinistroV.CodItm == c.avisoV.CodItm &&
c.sinistroV.NumApo == c.avisoV.NumApo &&
c.sinistroV.NumAvs == c.avisoV.SeqNumAvs).ToList();
var result=FirstDbContextTable.Join(sgsContext.EmsEmissao,
sinistro1 => sinistro1.sinistroV.CodCtrtAvs,
emissao => emissao.CodCtrt,
(sinistro1, emissao) => new {
sinistroC = sinistro1,
emissaoC = emissao })
.Where(c => c.sinistroC.sinistroV.CodCtrtAvs == c.emissaoC.CodCtrt &&
c.emissaoC.CodEmis == c.sinistroC.avisoV.CodEms)
.Where(x => x.sinistroC.sinistroV.NumApo == apolice &&
x.emissaoC.StsEmis == emissao &&
x.emissaoC.NumEndosso ==endosso &&
x.sinistroC.sinistroV.CodItm == cod_itm &&
x.sinistroC.sinistroV.CodCbe == cbeCod)
.Select(x => x.sinistroC)
.ToList();
I migrate my old project to the new EF Core and found this problem
My old code:
private IQueryable<SeriesData> GetSeriesData(IQueryable<Series> query, long? userId = null)
{
DateTime date = DateTime.Today.AddMonths(1);
IQueryable<SeriesData> seriesDataQuery = query.Select(x => new SeriesData
{
Series = x,
Subscribed = userId.HasValue && x.Subscriptions.Any(y => y.UserId == userId),
CurrentSeasonNumber = x.Episodes.Where(z => z.ReleaseDate.HasValue && z.ReleaseDate < date).Max(y => y.SeasonNumber),
Channel = x.Channel,
Country = x.Channel.Country,
ReleaseGroups =
x.Episodes.SelectMany(z => z.Releases)
.Select(y => y.ReleaseGroup)
.Distinct() // 1
.OrderBy(y => y.Name) // 2
.Select(r => new ReleaseGroupData
{
ReleaseGroup = r,
Subscribed =
userId.HasValue &&
x.Subscriptions.Any(y => y.UserId == userId && y.ReleaseGroupId == r.Id)
}).ToList()
});
return seriesDataQuery;
}
When i execute this query i get "InvalidOperationException: Sequence contains more than one element" exception
But if i swap line 1 and 2 everything works.
I have function
public async Task<IQueryable<Document>> GetDocuments(...)
in which I search for documents under some given conditions. Some conditions can be skipped. At the end I perform union of these queries.
var documents = await documentService.GetDocuments(this, userId,
roleShowFullNumber, param.OrderColName(), param.SearchValue, filter);
var usersGroupsId = filter.UsersGroupsId;
if (usersGroupsId != null)
{
if (!usersGroupsId.Contains("All"))
{
IQueryable<Document> myDocs = Enumerable.Empty<Document>().AsQueryable();
if (usersGroupsId.Contains("myOrders"))
{
myDocs = documents.Where(x => x.OwnerId == userId || x.UserId == userId);
usersGroupsId = usersGroupsId.Where(x => x != "myOrders").ToArray();
}
IQueryable<Document> wards = Enumerable.Empty<Document>().AsQueryable();
if (usersGroupsId.Contains("wards"))
{
var relatedUserId = _db.Users.Where(x => x.Id == userId).Select(x => x.RelatedUserId).FirstOrDefault();
if (relatedUserId != null)
{
var myWards = _db.kh__Kontrahent.Where(x => x.kh_IdOpiekun == relatedUserId);
var myWardsUsers = _db.Users.Where(x => myWards.Any(w => w.kh_Id == (x.RelatedCustomerId == null ? -1 : x.RelatedCustomerId)));
wards = documents.Where(x => (myWardsUsers.Any(w => x.UserId == w.Id) || myWardsUsers.Any(w => x.OwnerId == w.Id)));
usersGroupsId = usersGroupsId.Where(x => x != "wards").ToArray();
}
}
IQueryable<Document> groups = Enumerable.Empty<Document>().AsQueryable();
if (usersGroupsId.Length > 0)
{
var usersGroups = _db.Groups.Where(x => usersGroupsId.Contains(x.Id.ToString()));
var usersList = usersGroups.Select(x => x.Users);
var users = usersList.SelectMany(x => x);
var usersId = users.Select(x => x.Id);
groups = _db.Documents.Where(x => (usersId.Any(u => u == x.OwnerId) || usersId.Any(u => u == x.UserId)));
}
documents = myDocs.Union(wards).Union(groups);
}
}
But if one of these partial queries is empty (was skipped) when I try obtain these documents in way shown below I got error.
var documentsPaginated = await documents.Skip(param.Start)
.Take(param.Length)
.ToListAsync();
Error: The source IQueryable doesn't implement IDbAsyncEnumerable.
How can I make this function to be able to skip some sub queries and then union all. I would prefer not to change function return value.
Try this, althought your code seems to have a massive amount of code smell...
public async Task<IQueryable<Document>> GetDocuments(...)
var documents = await documentService.GetDocuments(this, userId,
roleShowFullNumber, param.OrderColName(), param.SearchValue, filter);
var usersGroupsId = filter.UsersGroupsId;
if (usersGroupsId != null)
{
if (!usersGroupsId.Contains("All"))
{
IQueryable<Document> myDocs = null;
if (usersGroupsId.Contains("myOrders"))
{
myDocs = documents.Where(x => x.OwnerId == userId || x.UserId == userId);
usersGroupsId = usersGroupsId.Where(x => x != "myOrders").ToArray();
}
IQueryable<Document> wards = null;
if (usersGroupsId.Contains("wards"))
{
var relatedUserId = _db.Users.Where(x => x.Id == userId).Select(x => x.RelatedUserId).FirstOrDefault();
if (relatedUserId != null)
{
var myWards = _db.kh__Kontrahent.Where(x => x.kh_IdOpiekun == relatedUserId);
var myWardsUsers = _db.Users.Where(x => myWards.Any(w => w.kh_Id == (x.RelatedCustomerId == null ? -1 : x.RelatedCustomerId)));
wards = documents.Where(x => (myWardsUsers.Any(w => x.UserId == w.Id) || myWardsUsers.Any(w => x.OwnerId == w.Id)));
usersGroupsId = usersGroupsId.Where(x => x != "wards").ToArray();
}
}
IQueryable<Document> groups = null;
if (usersGroupsId.Length > 0)
{
var usersGroups = _db.Groups.Where(x => usersGroupsId.Contains(x.Id.ToString()));
var usersList = usersGroups.Select(x => x.Users);
var users = usersList.SelectMany(x => x);
var usersId = users.Select(x => x.Id);
groups = _db.Documents.Where(x => (usersId.Any(u => u == x.OwnerId) || usersId.Any(u => u == x.UserId)));
}
if(myDocs != null)
documents = documents.Union(myDocs);
if(wards != null)
documents = documents.Union(wards);
if(groups != null)
documents = documents.Union(groups);
}
}
It appears that ToListAsync can't be used interchangeably with linq, but only in an EF query.
Quote from MSDN
Entity Framework 6 introduced a set of extension methods that can be used to asynchronously execute a query. Examples of these methods include ToListAsync, FirstAsync, ForEachAsync, etc.
Because Entity Framework queries make use of LINQ, the extension methods are defined on IQueryable and IEnumerable. However, because they are only designed to be used with Entity Framework you may receive the following error if you try to use them on a LINQ query that isn’t an Entity Framework query.
The source IQueryable doesn't implement IDbAsyncEnumerable{0}. Only sources that implement IDbAsyncEnumerable can be used for Entity Framework asynchronous operations. For more details see http://go.microsoft.com/fwlink/?LinkId=287068.
I have the query:
var q = db.tblArcadeGamePlays
.Where(c => c.GameID == GameID && c.ReferalID != 0 && c.ReferalID != null)
.GroupBy(r => new { r.ReferalID })
.Select(g => new { Plays = g.Count(), URL = g.Key.ReferalID })
;
tblArcadeGamePlays also has a field Date, in the group I'd like to return the earliest observed date that group contains.
How would I do this?
.Select(g => new {
Plays = g.Count(), URL = g.Key.ReferalID,
MinDate = g.Min(x => x.Date
});
you might also find the LINQ syntax easier to read/maintain here, but... the extension syntax will work too. But as LINQ:
var q = from c in db.tblArcadeGamePlays
where c.GameID == GameID && c.ReferalID != 0 && c.ReferalID != null
group c by c.ReferalID into g
select new {
Plays = g.Count(), URL = g.Key.ReferalID, MinDate = g.Min(x=>x.Date)
};
this might work
var firstIndex = q.Min(c => c.Date);
var q = db.tblArcadeGamePlays .Where(c => c.GameID == GameID && c.ReferalID != 0 && c.ReferalID != null) .GroupBy(r => new { r.ReferalID }) .Select(g => new { Plays = g.Count(), URL = g.Key.ReferalID , Date = g.Min(cc=>cc.DateField) }) ;
Replace DateField with your actual property
How could this be re-written using LINQ methods instead of inline query style?
var cp = from DataRow r in rptDataPkg.Datasets.Item(0).Result.Rows
where (r.Field<string>("UnitItem") == "PC") &&
(r.Field<string>("UnitItem") == "Hs") &&
(r.Field<string>("UnitItem") == "U")
select new CurrProjected
{
doAddUp = (r.Field<Decimal>("Fld1") + r.Field<Decimal>("Fld2"))
== r.Field<Decimal>("Fld3")
};
I prefer this syntax to the other solutions, personally.
var cp = rptDataPkg.Datasets.Item(0).Result.Rows
.Where(r => r.Field("UnitItem") == "PC")
.Where(r => r.Field("UnitItem") == "Hs")
.Where(r => r.Field("UnitItem") == "U")
.Select(r => new CurrProjected
{
doAddUp = (r.Field("Fld1") + r.Field("Fld2"))
== r.Field("Fld3")
});
Try the following
var cp = rptDataPkg.Datasets.Item(0).Result.Rows
.Cast<DataRow>()
.Where(r => (r.Field<string>("UnitItem") == "PC") &&
(r.Field<string>("UnitItem") == "Hs") &&
(r.Field<string>("UnitItem") == "U"))
.Select(r => new CurrProjected
{
doAddUp = (r.Field<Decimal>("Fld1") + r.Field<Decimal>("Fld2"))
== r.Field<Decimal>("Fld3")
});