Develop Reference

Read Data from table with no relationship

I have some global information (Company name, street, phone, …) stored in a table "CompInfo".
This table has only one entry and has no relationship to other tables.
Now I need this information in a view to generate, i.e. offers.
I tried to add this data in the controller, but I don't know how I can send this info to my view.
Here is my controller:
public async Task<IActionResult> Offer(int qry_offer)
{
ViewData["Message"] = "Offer";
var x412Context = _context.Offer
.Where(m => m.Id == qry_offer);
x412Context = x412Context
.Include(o => o.Kunde)
.Include(o => o.Mandant)
.Include(m => m.OfferPos)
.ThenInclude(m => m.Ust)
;
return View(await x412Context.ToListAsync());
}
First I add the following code
var Comp_Info = _context.CompInfo
.Where(m => m.Id == 1);
With breakpoints and debugging I see that Comp_Info has the information I require.
But I don´t know how to get this info to my view.
I tried
ViewData["street"] = Comp_Info.street;
But this doesn't work.
Does anyone have an idea how I can transmit the data to the view?

You can return a viewmodel in your Offer method that looks like this :
public class FooVM
{
public List<Offer> Offers {get; set;}
public CompInfo CompInfo{get; set;}
}
and in your controller initilize the FooVm like this:
var vm = new FooVM
{
Offers = await x412Context.ToListAsync(),
CompInfo = Comp_Info
};
and then in your Offer Method you return View(vm);
then your Offer.cshtml will look something like :
#model FooVm;
// some html code
#foreach (var offer in Model.Offers)
{
// Do something
}
<span>#Model.CompInfo.Street</span>

you can implement another class which should have members as the list (of the same type x412Context.ToListAsync()) and another member which will have the same datatype as Comp_Info.street.
then you can return the same class object to the view like return View(newClassObj);, you can access it as we do to access model class members in view.

Is there a way I can cache a LINQ parameter and reuse it later?

Is there a way I can cache a LINQ parameter and reuse it later for optimization?
Here is my situation.
public interface IEmployee
{
ProjectCollection GetProjects();
// ...
}
public class ProjectCollection
{
List<Project> EmployeeProjects { get; private set; }
// ...
}
public class Project
{
public Guid ProjectId { get; private set; }
// ...
}
Now given a list of employees List, and a given ProjectId (guid), I need to retrieve the Project object.
I've tried a combination of two LINQ statements, one to find the right employee, and one to find the right project. But is there a way to do it in one statement, or at least optimize it by caching the employee somewhere?
public Project GetProject(List<IEmployee> employees, Guid id)
{
Project rtn = null;
// Step 1: Retrieve the employee who has the right project.
var employeeWithProject = employees.Where (e => e.GetProjects().EmployeeProjects.Any(p => p.ProjectId.Equals(guid))).FirstOrDefault(); // Note: This retrieves the employee. But I need to cache the part [e.GetProjects().EmployeeProjects] to query it later.
if employeeWithProject != null)
{
// Step 2: Retrieve the project itself.
rtn = employeeWithProject.GetProjects().EmployeeProjects.Where(p => p.ProjectId.Equals(guid)).FirstOrDefault(); // Note: This retrieves the actual project from the previously set employeeWithProject
}
return rtn; // nothing found
}
I really don't like this solution, and was wondering if anyone could help me optimize it. It basically iterates through the Projectcollection twice. So if anyone can think of a way to do the whole thing with a single LINQ statement I'd appreciate it.
Thanks.

you could try something like this:
var employeeWithProject = employees
.Select(e => e.GetProjects().EmployeeProjects.FirstOrDefault(p => p.ProjectId.Equals(guid)))
.FirstOrDefault(x=> x != null);
here you're selecting the wanted projects from the employees, and then getting the first one that isn't null

SelectMany could work here too.
static public Project GetProject(List<Employee> employees, Guid id)
=> employees
.SelectMany( e => e.GetProjects()?.EmployeeProjects)
.FirstOrDefault( p => p.ProjectId == id);

How to convert early bound query to IQueryable<TEntity>

Assuming that AccountSet returns an IQueryable<Account>, how can I convert this early binding:
XrmServiceContext _xrmServiceContext;
var result = _xrmServiceContext.AccountSet.FirstOrDefault(x => x.Id == locationGuid);
Into something that is more reusable like:
_xrmServiceContext.Where(Set == "Account").FirstOrDefault(x => x.Id == locationGuid);
AccountSet is defined as:
public System.Linq.IQueryable<Xrm.Account> AccountSet
{
get
{
return this.CreateQuery<Xrm.Account>();
}
}
How do I generalize this to be reusable for any IQueryable member of XrmServiceContext ?

As long as the Id is the primary key you can use that in conjunction with find to make a generic call
public T Get<T>(object[] Id)
where T : class
{
return _xrmServiceContext.Set<T>().Find(Id )
}
if your looking for an IQueryable that may be a bit harder but you can find out how to do that off of a previous question I asked:
Entity Framework Filter By PrimaryKey

Courtesy of this post, I've found the following solution:
private static T EntityGet<T>(Guid id)
where T : Entity
{
T item =
(
from query in Context.CreateQuery<T>()
where query.Id == id
select query
).Single();
return item;
}

LINQ Order List By SubObject with possible Null Reference

After some hours of trying and researching I'm still stuck with the following problem.
I have a list of customers, each customer has a list of orders. I now want to sort the list of customers by their highest order number.
Another aspect is that not every customer has an order, so for sorting i want to replace the missing order number with an “-“ sign.
My first approach won’t work because it can’t compare the object, but it explains the problem quite well.
customers.OrderBy(m => m.Orders == null ? "-" : m.Orders.LastOrDefault().OrderNumber.ToString());
After reading the link below I ended up with this code, but that is not working either.
how do I sort a collection with child property?
customers.OrderBy(c => c.Orders.OrderBy(o => o == null ? "-" : o.OrderNumber.ToString()).Select(o => o == null ? "-" : o.OrderNumber.ToString()).ToList();
Can someone tell me how I can do this best?
Best Regards
Edit:
Here are the entities (not full entity) I'm trying to sort.
I'm working with entity framework and I've already read out the customers as an IQueryable and now I need to sort this.
Customer
public class Customer
{
public int ID { get; set; }
public virtual List<Order> Orders { get; set; }
}
Order
public class Order {
public int ID { get; set; }
public int OrderNumber { get; set; }
public virtual Customer Customer { get; set; }
}
Now the customer does not necessarily have a list of orders associated.
Meaning a customer can have 0,1 or n orders assigned to him, that's what I meant with null.

I now want to sort the list of customers by their highest order number.
Then the following should do the trick:
var result = customers.OrderBy(c => c.Orders.Max(o => (int?)o.OrderNumber));
The int? cast is needed to let Max function return null for customers w/o orders. This normally would put them at the beginning of the sort order.
In case you want to put customers w/o orders at the end, the simplest would be to use int.MaxValue (assuming you have no OrderNumber == int.MaxValue):
var result = customers.OrderBy(c => c.Orders.Max(o => (int?)o.OrderNumber) ?? int.MaxValue);

You could first remove the customers with no Orders and then add them back with Concat()
customers
.Where(c => c.Orders.Count() != 0)
.OrderBy(c => c.Orders.OrderBy(o => o.OrderNumber).Select(o => o.OrderNumber).FirstOrDefault())
.Concat(customers.Where(c => c.Orders.Count() == 0))
.ToList();
Let me know if that works for your use-case.
So Long

asp.net is there a way to get id in list?

I have a many-to-many between 'Edital' and 'Graduando' and I created a entity called 'EditalGraduando'. Now I want to know every 'edital' that 'graduando' subscribe using the graduando id. So I did this:
public IQueryable<int> GetGraduandosIds(int editalId)
{
var graduandosId = db.EditalGraduandoe.Where(e => e.EditalId == editalId).Select(i => i.graduandoID);
return graduandosId;
}
There's a way to do a select in the entety 'Graduando' using this result? Like this: SQL WHERE ID IN (id1, id2, ..., idn)

Yes, you can do this:
public IQueryable<Graduandoe> GetGraduandos(IEnumerable<int> graduandosIds)
{
return db.Graduandoe.Where(g => graduandosIds.Contains(g.graduandoID));
}
Alternatively, you could have navigation properties, and you can write the following instead of the two functions:
public IQueryable<Graduandoe> GetGraduandos(int editalId)
{
return db.EditalGraduandoe.Where(e => e.EditalId == editalId).Select(i => i.Graduandoe);
}