I want to display two tables data using join in web api. I have tried with this code, but getting error - The type of one of the expressions in the join clause is incorrect. Type inference failed in the call to 'Join'. and here is my code
public List<tblEmpTask> GettblEmpTasks()
{
var q = (from n in db.tblEmpTasks
join c in db.tblEmployees on n.intEmpCode equals c.intEmpCode
select new
{
n.strTaskName,
n.dtStart,
c.strEmployeeName,
}).ToList();
return q;
}
Any solution will be helpful.
Related
Hi I am using a Jqwidgets Grid to display my data. It has a build in possibility to use filters but if you filter your records on the server side you have to build your own query. As I am working with Linq I thought to use the Dynamic Linq Library for Asp net core. Problem is there are not many examples or explanations how to do this. But I am busy for days now and not getting very far.The way I am setup; I have a normal Linq query:
var Mut = from M in _DB.Mutations
join S in _DB.Shifts on M.ShiftId equals S.ShiftId
join U in _DB.RoosterUsers on M.UserId equals U.RoosterUserId
join D in deps on M.UserId equals D.UserId
join DD in _DB.Departements on D.DepartementID equals DD.DepartementId
select new MutationModel
{
MutId=M.MutationId,
Naam=U.FirstName + " " + U.LastName,
UserId=M.UserId,
Departement= DD.DepartementName,
MutationType = S.publicName,
MutationGroup = S.ShiftType.ToString(),
DateTot =M.DateTill,
TijdVan=M.DateStartOn,
TijdTot=M.DateTill,
Status=CreateStatus(M.Tentative, M.ApprovedOn, M.Processed, M.CancelRefId, M.Deleted)
};
This query is running OK and gives me all the data I need for the Grid.
Then for the filter I would like to add a dynamic Linq Query using the System.Linq.Dynamic.Core library
But this is as far as I get things working until now:
var outQuery = Mut.Where("Status = #0 and UserId = #1", "Nieuw", "KLM22940").Select("Status");
My questions now :
1. In the where clause If I make the fieldname variable I get an error. how to do this??
2. In the Select Clause, how to add multiple Columns? (actually I just like to output all columns.)
Best would be to see an example. has somebody used Dynamic Linq to build a dynamic linq query for the JQWidgets Grid?
Thank you very much.
In what way you are trying to use fieldname variable in where clause ?
If you want to output all columns you can use ToList()
like
var outQuery = Mut.Where("Status = #0 and UserId = #1", "Nieuw", "KLM22940").ToList();
If you want to get some specific columns you can use Select clause like this
var outQuery = Mut.Where("Status = #0 and UserId = #1", "Nieuw", "KLM22940").Select("new(Status,UserId )");
This Select clause creates data class which contains Status and UserId properties and returns a sequence of instances of that data class.
How do I left outer join two tables on two fields in linq?
I have a sql:
select a.*, b.* from courselist as a
left outer join Summary as b
on a.subject = b.Subject and a.catalog =
b.Catalogno
where a.degree_id = 1
order by a.sequenceNo
Below is my linq query, but there is error underline "join", failed in the call to "Groupjoin". I don't know how to correct that.
var searchResults = (from a in db.courselist
join b in db.Summary on
new { a.subject,a.catalog } equals
new { b.Subject, b.Catalogno } into ab
where a.degree_id == 1
orderby a.degree_sequenceNo
from b in ab.DefaultIfEmpty()
select new
{
Courselist = a,
Summary = b
}
).ToList();
Thanks.
I've checked your code again,
I found it's fault
you just need to specify join parameters name like this:
new { suject = a.subject, catalog = a.catalog } equals
new { suject = b.subject, catalog = b.Catalogno } into ab
It seems you are missing the reference, the query doesn't have an error
try to use this:
using System.Linq;
The main issue when people start using LINQ is that they keep thinking in the SQL way, they design the SQL query first and then translate it to LINQ. You need to learn how to think in the LINQ way and your LINQ query will become neater and simpler. For instance, in your LINQ you don't need joins. You should use Associations/Navigation Properties instead. Check this post for more details.
There should be a relationship between courselist and Summary, in which case, you can access Summary through courselist like this:
var searchResults = (from a in db.courselist
where a.degree_id == 1
orderby a.degree_sequenceNo
select new {
Courselist = a,
Summary = a.Summary
}).ToList();
If there is no relationship between the two, then you should reconsider your design.
I'm attempting to perform two left outer joins in my CRM online 2015 Update 1 instance, but I am getting an error. This is what I have currently:
var query_join8 = from a in crmContext.AccountSet
join c in crmContext.ContactSet
on a.PrimaryContactId.Id equals c.ContactId
into gr
from c_joined in gr.DefaultIfEmpty()
join c in crmContext.ContactSet
on a.Name equals c.FullName
into gr2
from c2_joined in gr2.DefaultIfEmpty()
select new
{
contact_name = c_joined.FullName,
account_name = a.Name,
other_name = c2_joined.FullName
};
When I attempt to execute it, I get this error:
An exception of type 'System.NotSupportedException' occurred in
Microsoft.Xrm.Sdk.dll but was not handled in user code
Additional information: The method 'GroupJoin' cannot follow the
method 'SelectMany' or is not supported. Try writing the query in
terms of supported methods or call the 'AsEnumerable' or 'ToList'
method before calling unsupported methods.
If I comment out the second Join, it works fine:
var query_join8 = from a in crmContext.AccountSet
join c in crmContext.ContactSet
on a.PrimaryContactId.Id equals c.ContactId
into gr
from c_joined in gr.DefaultIfEmpty()
//join c in crmContext.ContactSet
//on a.Name equals c.FullName
//into gr2
//from c2_joined in gr2.DefaultIfEmpty()
select new
{
contact_name = c_joined.FullName,
account_name = a.Name,
//other_name = c2_joined.FullName
};
Microsoft Documentation:
Defining how to perform a Left Join: http://msdn.microsoft.com/en-us/library/gg509017.aspx#LeftJoin
Blog Describing that it is supported: http://blogs.msdn.com/b/crminthefield/archive/2013/01/14/crm-2011-sdk-query-limitations-by-api.aspx
The documentation on CRM 2015 still states outer joins are not supported. (MSDN: Use LINQ to construct a query) I know there is also an example on MSDN showing a left join (Sample: Complex LINQ queries), but I doubt if under the hood this is actually transformed into a single QueryExpression. So, I guess you are hitting the limits of the capabilities of Ling for CRM.
We are using CRM 2011. We have Contracts with Entity Reference to Product and each Product has an Entity Reference to a Subject. Given a Contract Guid, I need to retrieve the Subject Guid.
I am a beginner at LINQ but I coded:
var subject = from s in context.SubjectSet
join product in context.ProductSet
on s.Id equals product.SubjectId.Id
join contract in context.ContractSet
on product.Id equals contract.ce_ProductId.Id
where contract.Id == gContractId
select s;
foreach (var s in subject)
{
newReportableAction.ce_SupergroupRegarding =
new EntityReference(Xrm.Subject.EntityLogicalName, new Guid(s.Id.ToString()));
}
This throws an error:
AttributeFrom and AttributeTo must be either both specified or both ommited. You can not pass only one or the other. AttributeFrom: , AttributeTo: ce_ProductId
What does this error mean?
How can I get the Guid?
Update:
I tried breaking the query into parts to see where the error was being generated from so I had:
var query = from product in context.ProductSet
join contract in context.ContractSet
on product.Id equals contract.ce_ProductId.Id
This gives:
"The type of one of expressions in the join clause is incorrect. Type inference failed in the call to 'Join'"
Thank you to all who help...
I don't think you can use the .Id property right off the entity in Linq statements. Try this instead:
var query = from product in context.ProductSet
join contract in context.ContractSet
on product.ProductId equals contract.ce_ProductId.Id
Notice product.ProductId instead of product.Id.
So we copy and paste the exact same query from LinqPad into our EF 4.3 application, pointed at the exact same database and get a different result. In LinqPad we get 2 records returned. In our application we reaise an error "Object reference not set to an instance of an object."
var Shippings = shippingRepository.All.ToArray();
var SalesOrderHeaders = salesOrderHeaderRepository.All.ToArray();
var Customers = customerRepository.All.ToArray();
var Stores = storeRepository.All.ToArray();
var Departments = departmentRepository.All.ToArray();
var toShip = from sh in Shippings
join h in SalesOrderHeaders on sh.OrderId equals h.SalesOrderHeaderId
join c in Customers on h.CustomerId equals c.CustomerId
join st in Stores on h.StoreId equals st.StoreId
join d in Departments on h.DepartmentId equals d.DepartmentId into outer
from o in outer.DefaultIfEmpty()
select new
{
OrderId = sh.OrderId,
CustomerName = c.Name,
StoreName = st.Name,
DepartmentName = (o.Name == null) ? o.Name : "None",
DeliveryDate = h.DeliveryDateTime
};
In the application code, when we remove the outer join (to add Departments) and it's associated field the query returns the same 2 records asn in LinqPad.
Does anyone have any insight into how to fix this feature?
Click on "Add a connection" in linqpad and select datacontext from assembly like
You can choose Entity Framework datacontext or Entity Framework BDContext with POCO depending upon your scenario. click next and provide path to the assembly along with connection string and you will be good to go.
In LINQPad are you actually querying against your entity model? Take a look at this link if you aren't. I had a similar problem when starting out and didn't realize I had set up a default LINQ to SQL connection earlier and was querying against that.