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Reuse LINQ select function


Reuse LINQ select function

By : oysteinheimark
Date : November 22 2020, 10:38 AM
it should still fix some issue Try storing the Func in a variable, and re-use it. Something like this:
code :
internal static IQueryable<UserModel> SelectUser(this IQueryable<User> query, bool getChildren) {
    log.DebugFormat("create the select statement for an individual user {0}", getChildren ? "with children" : "without children");

    var res = query.Select(u => new UserModel {
        // [...] unimportant stuff
        Groups = u.Groups.AsQueryable().Select(MyLinqExpressions.fSelect).Take(10),
        CreatedGroups = !getChildren ? null : u.CreatedGroups.AsQueryable().Select(MyLinqExpressions.fSelect).Take(10)
        // [...] more stuff like above just different types
    });
    return res;
}
public static class MyLinqExpressions {
    public static Func<Group,GroupModel>
        fSelect = g => new GroupModel {
            Name = g.Name,
            Description = g.Description,
            ID = g.ID
        };
}


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How to reuse part of Linq to Entity Select expression in EF4.1 code only scenario

How to reuse part of Linq to Entity Select expression in EF4.1 code only scenario


By : user3163693
Date : March 29 2020, 07:55 AM
should help you out I would create a new class CLASSNAME that has two properties
PrintJobReportItem type GROUPING IEnumerable>
code :
public static IQueryable<CLASSNAME> EXTENSIONNAME<TKey, TSource>(this IEnumerable<IGrouping<TKey, TSource>> source)
{
  return from g in source
         select new CLASSNAME
         {
           PrintJobReportItem = new PrintJobReportItem
                                {
                                  TotalPagesPrinted = g.Sum(p => p.PagesPrinted),
                                  AveragePagesPrinted = etc...,
                                  PercentOfSinglePagePrintJobs = etc...,
                                },
           GROUPING = g
         };
}
var q1 = repo.GetQuery<PrintJob>()
    .GroupBy(pj => pj.UserName)
    .EXTENSIONNAME()
    .Select(g => new PrintJobByDepartmenReportItem
                 {
                    PrintJobReportItem = g.PrintJobReportItem,
                    DepartmentName = g.GROUPING.Key,
                    NumberOfUsers = g.GROUPING.Select(u => u.UserName).Distinct().Count()

                 });
Is it possible to reuse parts of a LINQ to Entities select statement?

Is it possible to reuse parts of a LINQ to Entities select statement?


By : Hetty
Date : March 29 2020, 07:55 AM
this will help
As an alternative to Func<>s, you can also make use of extension methods to reuse the conversions between your entity types to and other POCOs.
code :
public static IQueryable<CustomerDevice> ToCustomerDevice(this IQueryable<PTT_CUSTOMER_DEVICES> devices)
{
    return devices.Select(d => new CustomerDevice
    {
        customerAssetTag = d.CustomerAssetTag,
        customerDeviceID = d.CustomerDeviceID
    }
}
public static Model ToModel(this PTS_MODELS model)
{
    return new Model()
    {
        ModelID = model.ModelID,
        Name = model.Name,
        Make = new Make()
        {
            MakeID = model.PTS_MAKES.MakeID,
            Name = model.PTS_MAKES.Name
        }
    };
}

public static IEnumerable<CustomerDevice> ToCustomerDevice(this IQueryable<PTT_CUSTOMER_DEVICES> devices)
{
    return devices
        .Include(d => d.PTS_MODELS.PTS_MAKES)
        .AsEnumerable() // Evaulate everything that follows in memory
        .Select(d => new CustomerDevice
        {
            customerAssetTag = d.CustomerAssetTag,
            customerDeviceID = d.CustomerDeviceID,
            Model = d.PTS_MODELS.ToModel()
        });
}
Reuse select new object in linq statement

Reuse select new object in linq statement


By : mttyice
Date : March 29 2020, 07:55 AM
wish helps you Below is my linq code and it works. My question is how I can "reuse" those part new ContactResponse, and new AddressResponse in a function to reuse it in another query? , If I correct understand your question, then try this:
code :
 Func<WorkshopContact, ContactResponse> contactResponseProjection= p => new ContactResponse
 {
   Id = p.Contact.Id,
   Type = p.Contact.ContactType.Description,
   Code = p.Contact.ContactType.Code,
   Value = p.Contact.Value
 };
...
  Contacts = a.WorkshopContacts.Select(contactResponseProjection).ToList(),
...

Why can't I reuse a function in LINQ to SQL

Why can't I reuse a function in LINQ to SQL


By : user3837691
Date : March 29 2020, 07:55 AM
I wish did fix the issue. In the second snippet, the logic is being translated into a lambda expression which is then compiled into an expression tree... the two query translations are:
How to reuse LINQ Select Expression with arguments

How to reuse LINQ Select Expression with arguments


By : z l
Date : March 29 2020, 07:55 AM
I hope this helps . Rather than having a field that stores the expression, have a method that creates the expression that you need given a particular string:
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