Linq innere Verknüpfung zu komplexen Abfrage

Question

var workbasketitems = new[] { //workbasketitems 
    new { TaskId = 10, WorkGroupId = 100, ActionUserId =1000, Work = "item 0" }, 
    new { TaskId = 11, WorkGroupId = 101, ActionUserId =1001, Work = "item 1" }, 
    new { TaskId = 12, WorkGroupId = 102, ActionUserId =1002, Work = "item 2" } 
}; 
var workflowtasks = new[] { //workflowtasks 
    new { TaskId = 10, TaskDesc = "TaskDesc 0" }, 
    new { TaskId = 11, TaskDesc = "TaskDesc 1" }, 
    new { TaskId = 12, TaskDesc = "TaskDesc 2" } 
}; 
var workgroup = new[] { //workgroup 
    new { WorkGroupId = 100, WGDesc = "WGDesc 0" }, 
    new { WorkGroupId = 101, WGDesc = "WGDesc 1" }, 
    new { WorkGroupId = 102, WGDesc = "WGDesc 2" } 
}; 
var applicationuser = new[] { //applicationuser 
    new { AUId = 1000, AUDesc = "AUId 0" }, 
    new { AUId = 1001, AUDesc = "AUId 1" } 
}; 
    var results = from wb in workbasketitems 
     join wft in workflowtasks on wb.TaskId equals wft.TaskId 
     join wg in workgroup on wb.WorkGroupId equals wg.WorkGroupId   
     select new { wft.TaskDesc, wg.WGDesc, wb.ActionUserId, wb.Work}; 
    results.Dump(); 

    var resultsInner = from wb in results 
     join au in applicationuser on wb.ActionUserId equals au.AUId into wbl 
     from auList in wbl.DefaultIfEmpty() 
     select new { wb.TaskDesc, wb.WGDesc, Desc = (auList == null? "BlAnk": auList.AUDesc), wb.Work};  
    resultsInner.Dump(); 

Gibt es eine Möglichkeit die folgenden Linq Abfragen zu kombinieren, und ist so hilfreich wie ich behalten wollen Dinge wartbar. Das obige funktioniert in Linqpad, wobei resultsInner ein Innerer Join der neu erstellten Ergebnistabelle ist.

Answer 1

Sie sind fast da. Fügen Sie einfach die zusätzlichen left join, die Sie in der zweiten Abfrage an der ersten Abfrage ausführen:

var results = from wb in workbasketitems 
       join wft in workflowtasks on wb.TaskId equals wft.TaskId 
       join wg in workgroup on wb.WorkGroupId equals wg.WorkGroupId 
       join au in applicationuser on wb.ActionUserId equals au.AUId into wbl 
       from auList in wbl.DefaultIfEmpty() 
       select new { wft.TaskDesc, wg.WGDesc, Desc = (auList == null ? "BlAnk" : auList.AUDesc), wb.Work }; 

---

Sie auch die andere Überlastung von DefaultIfEmpty verwenden kann, um festzulegen, was in einem Fall zu tun, wenn die left join Ergebnisse mit ein null:

var results = from wb in workbasketitems 
       join wft in workflowtasks on wb.TaskId equals wft.TaskId 
       join wg in workgroup on wb.WorkGroupId equals wg.WorkGroupId 
       join au in applicationuser on wb.ActionUserId equals au.AUId into wbl 
       from auList in wbl.DefaultIfEmpty(new { AUId = wb.ActionUserId, AUDesc = "Blank" }) 
       select new { wft.TaskDesc, wg.WGDesc, Desc = auList.AUDesc, wb.Work }; 

Answer 2

Haben Sie für diese suchen:

var results = from wb in workbasketitems 
    join wft in workflowtasks on wb.TaskId equals wft.TaskId 
    join wg in workgroup on wb.WorkGroupId equals wg.WorkGroupId 
    join au in applicationuser on wb.ActionUserId equals au.AUId into wbl 
    from auList in wbl.DefaultIfEmpty() 
    select new { wft.TaskDesc, wg.WGDesc, Desc = (auList == null? "Blank": auList.AUDesc), wb.Work}; 

Verwandte zu maintainablity es keine Auswirkungen. Aber in diesem Fall haben Sie zusätzliche Projektionen weggelassen.