I have a small problem in my where clause in the linq expression below. If I put the number 3 instead of department.Id I get the desired result but when I use department.Id I get nothing in the resultset.
I also want to get a count for the number of filters for that filter name using the query again using distinct.
var dept = Page.RouteData.Values["department"];
var department = (from d in db.Departments
where d.Name.Replace(" ", "-") == dept
select new {d.Id, d.Name}).FirstOrDefault();
var query = from p in db.Products
join f in db.ProductFilters on p.Id equals f.ProductId into filters
from x in filters.Where(x => x.Product.DepartmentId == department.Id
/* if == 3 it works */)
select new { x.Name, x.Id };
Promoted to answer from comments:
Have you checked that the department instance is as you think it should be after the first linq statement - ie has an Id == 3?
Your first query is not finding any valid department and is therefore returning default which most probably means that departmend.Id == 0.
Related
how can i convert rows to column in entity framework!?
i have a result like this:
and i want this result:
my entity code i this :
(from loanPerson in context.LoanPersons.AsParallel()
join warranter in context.Warranters.AsParallel() on loanPerson.Id equals warranter.LoanPersonId
where loanPerson.Id == 84829
select new
{
loanPersonId = loanPerson.Id,
waranterId = warranter.WarranterPersonID,
}).ToList();
and number of the row always less than 3 and i want to have 3 column.
please let me know your answer.
tanks.
This query will return the only one row, where waranterIds will contain, at this particular case, three WarranterPersonID values, also this field is of List<int> type, because it's quantity not known at compile time:
var answer = (from loanPerson in context.LoanPersons.Where(x => x.Id == 84829)
join warranter in context.Warranters
on loanPerson.Id equals warranter.LoanPersonId
group warranter by loanPerson.Id into sub
select new
{
loanPersonId = sub.Key,
waranterIds = sub.Select(x => x.LoanPersonId).ToList()
//if you sure, that quantity equals 3,
//you can write this code instead of waranterIds:
//zamen1 = sub.Select(x => x.LoanPersonId).First(),
//zamen2 = sub.Select(x => x.LoanPersonId).Skip(1).First(),
//zamen3 = sub.Select(x => x.LoanPersonId).Skip(2).First()
}).ToList();
I have a query that returns a list of currencies and joins to a lookup table. The result is then put into a class object (which works fine):
var queryforobject = from x in db.CurrencyExchangeRates.AsNoTracking()
join c in db.CurrencyTypes.AsNoTracking() on x.CurrencyTypeID equals c.ID
orderby x.ID
select new CurrencyExchangeRateObject
{
ID = x.ID,
CurrencyID = c.ID,
Currency = c.Description,
ExchangeRate = x.ExchangeRate,
LastEditedDate = x.LastEditedDate,
LastEditedBy = x.LastEditedBy,
Active = x.Active
};
I want to make this more dynamic, so if no CurrencyTypeID is supplied then it will return the full list (as it does already) - otherwise if a CurrencyTypeID is supplied it will only show where X.CurrencyTypeID = ID.
Something along the lines of an inline if?
There are a few options for filtering the query based on CurrencyTypeID if a search value (named currencyTypeID in this answer) is supplied, but return all data if no currencyTypeID is supplied.
First option: You could add a where clause to your existing query expression. The WHERE clause below will return every record in the data set if null is passed in for the currencyTypeID variable, otherwise it will filter the results.
from x in db.CurrencyExchangeRates.AsNoTracking()
join c in db.CurrencyTypes.AsNoTracking() on x.CurrencyTypeID equals c.ID
where (currencyTypeID == null || x.CurrencyTypeID == currencyTypeID)
orderby x.ID
select new CurrencyExchangeRateObject {
ID = x.ID,
CurrencyID = c.ID,
Currency = c.Description,
ExchangeRate = x.ExchangeRate,
LastEditedDate = x.LastEditedDate,
LastEditedBy = x.LastEditedBy,
Active = x.Active
};
Alternatively: Since queryforobject is of type IQueryable<T>, you can use LINQ's fluent API to append a WHERE clause to the query inside an if statement. You need to be more careful about timing on this one though as it needs to be done before you force evaluation of the IQueryable with a foreach loop, .ToList(), .Select() or other LINQ methods that force evaluation.
if(currencyTypeID != null)
queryforobject = queryforobject.Where(cerObj => cerObj.CurrencyID == currencyTypeID);
I have the following two objects:
User
class User {
public int role;
}
Role
class Role {
public int id;
public string name;
}
be note that role property inside User is int and not Role, that's our limitations.
I want to join between all the users and each of his role. In the mapping objects there is no reference as you can understand, just a simple type (int).
How do I do that join statement?
It's called a theta join:
var a = (from u in session.Query<User>()
from r in session.Query<Role>()
where u.role == r.id
select new { u.Username, Role = r.name }).ToList();
Assuming you have a Username property on the User class.
Yes, this "theta join" (as I just learned this term) is very handy and let's us not worry about putting in pointless mapping relationships.
WARNING HOWEVER IN USING THIS!!! This tripped me up a lot.
Adding to the above example...
var list = new List<int>( { 2, 3 } ); // pretend in-memory data from something.
var a =
(from u in session.Query<User>()
from x in list
from r in session.Query<Role>()
where u.role == r.id
where r.id == x.id // pretend list wants to limit to only certain roles.
select new { u.Username, Role = r.name }).ToList();
THIS WILL BOMB with some NotSupported exception.
The trick is that anything coming from NHibernate Session must come LAST. So this alteration WILL work:
var a =
(from x in list
from u in session.Query<User>()
from r in session.Query<Role>()
where u.role == r.id
where r.id == x.id // pretend list wants to limit to only certain roles.
select new { u.Username, Role = r.name }).ToList();
And and BTW, you can use join as well, however you have to make sure if you have any nullable data types, that you use the .Value if you are joining to something not-nullable.
var a =
(from x in list
from u in session.Query<User>()
join r in session.Query<Role>() on u.role equals r.id
where r.id == x.id // pretend list wants to limit to only certain roles.
select new { u.Username, Role = r.name }).ToList();
And while we're at it, let's say you have a method that has some dynamic condition. In this example the 'list' which could be a list of roles to filter by, but don't filter at all if the list is not there. Well, if you do the .ToList() then you are causing this query to execute immediately. But instead you can add a condition and then execute it later:
var a =
from u in session.Query<User>()
join r in session.Query<Role>() on u.role equals r.id
where r.id == x.id // pretend list wants to limit to only certain roles.
select new { u.Username, Role = r.name, RoleID = r.id }; // Adding the Role ID into this output.
if (list != null) // assume if the list given is null, that means no filter.
{
a = a.Where(x => list.Contains(x.RoleID));
// WARNING. Unfortunately using the "theta" format here will not work. Not sure why.
}
var b = a.ToList(); // actually execute it.
var c = a.Select(x => new { x.Username, x.Role }).ToList() // if you insist on removing that extra RoleID in the output.
One last thing.. Sometimes some simple logic will fail when executed in the select new { .. } part. I don't have an explanation. In our case the logic was just converting a DB value of a uint to an Enumerator of a model. But to get around that, I just avoided doing that conversion while reading the data but saved the value. Then in a later step, after the data was loaded, I just did the conversion in another LINQ statement.
DISCLAIMER: While I wrote many of these things all the past several weeks, I did not put this code into my compiler to verify 100%.
I have this query that I am performing using entity framework 5 with MySql.
var employeeDetails = (from em in entities.employeemasters.AsEnumerable()
join sf in entities.salaryfitments.AsEnumerable()
on em.empID equals sf.empID into emsf
from x in emsf
where (x.edCode.ToString().Trim().Equals(txtEDCode.Text)
&& x.edCode != "SYS001")
select new { em, x });
The where (x.edCode.ToString().Trim().Equals(txtEDCode.Text) checks to see if there are any earnings/deductions stored for that employee and if so I can be able to get the amount figure.
I would like the query to return all employees and if they do not have a particular earnings/deductions matching txtEDCode.Text, then return a default value.
I cannot place .DefaultIfEmpty() after where (x.edCode.ToString().Trim().Equals(txtEDCode.Text)
What should I do to get the appropriate results?
Instead of returning the whole entities I'd create a new object with only the fields I was interested in and use a ternary if to provide the default value in the select statement, for example.
select new {
name = x.Name,
salary = x.Salary,
code = string.IsNullOrEmpty(x) ? "Blah" : x
}
I am trying to write dynamic Linq Library query to fetch record on condition,
Customers who has order count is greater than 3 and ShipVia field equal 2.
Below is my syntax what i have tried.
object[] objArr = new object[10];
objArr[0] = 1;
IQueryable<Customer> test = db.Customers.Where("Orders.Count(ShipVia=2)", objArr);
and
IQueryable<Customer> test = db.Customers.Where("Orders.Any(ShipVia=2).Count()", objArr);
But both are not working. In second query Any returns true so it won't work with Count.
Suggest me a way to implement this.
If you HAVE to use Dynamic Linq, your query should look like that:
db.Customers.Where("Orders.Count(ShipVia == 2) > 3");
How about something like this.
IQueryable<Customer> test = db.Customers.Where(c => c.Orders.Where(o => o.ShipVia ==2).Count() >2);
var grp = db.Customers.Where("ShipVia=2").GroupBy("ShipVia");
var test = from a in grp
where a.Count() > 3
select a.Key;
IQueryable<Customer> test =
from c in db.Customers
from o in c.Orders
where o.ShipVia == 2 // NOTE you need == not = for compare
group c by c into grp
select new {customer = grp.key, ordercount = grp.Count() };
Untested but I believe this should do it all in one statement, assuming Orders are a collection within Customer.
Note that your single = in your where clause is very dangerous as it'll assign 2 to all shipvias instead of test (==)