How can i lookup values from another table in Entity Framework - entity-framework

very new to this. Building a Tourettes pattern tracker for a friend.
I have two related tables in EF. How can I create an entry in the TicEntry table that has a foreign key requirment from the other table? I will populate TicType as it will remain pretty static.
A user needs to be able to create an TicEntry ideally with just Frequency, Severity, TicType selections. TicType should lookup from the TicType Table. Date will hopefully be auto, as well as TicEntryID which is an IDENTITY. But how do I deal with the TicTypeID when giving a model to my View?
Many thanks.
public enum Frequency { Low, Medium, High }
public enum Severity { Low, Medium, High }
public class TicEntry {
public int TicEntryID { get; set; }
public int TicTypeID { get; set; }
public DateTime DateTime { get; set; }
public Frequency? Frequency { get; set; }
public Severity? Severity { get; set; }
public virtual TicType TicType { get; set; }
}
public enum Type { Motor, Vocal, ComMotor, ComVocal }
public class TicType
{
public int TicTypeID { get; set; }
public Type? Type { get; set; }
public virtual ICollection<TicEntry> TicEntry { get; set; }
}

Let the user select the tic type from the Type enum. Then use the selected enum value to look up the TicType entry from the DB.
In the View.cshtml:
var availableTicTypes = new List<SelectListItem>(
new SelectListItem{ Value = Type.Motor, Text = "Motor", Selected = true },
new SelectListItem{ Value = Type.Vocal, Text = "Vocal", Selected = false }
// ...
);
#Html.DropDownListFor(m => m.TickType, availableTicTypes)
In your Controller:
var ticType = _dbContext.TicTypes.SingleOrDefault(t => t.Type == viewModel.TickType);
var tickEntry = new TicEntry {
TicType = ticType
// set other properties ...
};
_dbContext.TickEntries.Add(tickEntry);
_dbContext.SaveChanges();

Related

Combining multiple IQueryable from different object types for TreeList DataSource

I search for a way to combine two or more IQueryables from different Object types in order to use it as a datasource for my treelist.
For the treelist I use the DevExpress WinForms component "TreeList".
It provides me the properties "KeyFieldName" which is usually mapped to the "ID" and the ParentFieldName which is mapped to the parent id in order to build a hierarchy.
I use entity framework 6 as or mapper.
I have the two following classes I would need to combine:
XObject:
[Table("tbl_objects")]
public class XObject
{
[Column("id")]
public int Id { get; set; }
[Column("display_name")]
public String DisplayName { get; set; }
[Column("description")]
public String Description { get; set; }
[Column("usage_reason")]
public String UsageReason { get; set; }
[Column("is_network_compatible")]
public bool IsNetworkCompatible { get; set; }
[Column("ip_address")]
public String IpAddress { get; set; }
[Column("network_name")]
public String NetworkName { get; set; }
[Column("serial_number")]
public String SerialNumber { get; set; }
[Column("manufacturer_identification_code")]
public String ManufacturerIdentificationCode { get; set; }
[Column("web_link")]
public String WebLink { get; set; }
[Column("warranty")]
public int WarrantyInDays { get; set; }
[Column("ref_manufacturer")]
public virtual XManufacturer Manufacturer { get; set; }
[Column("ref_order")]
public virtual XOrder Order { get; set; }
[Column("ref_owner")]
public virtual XOwner Owner { get; set; }
[Column("ref_room")]
public virtual XRoom Room { get; set; }
[Column("ref_object_folder")]
public virtual XObjectFolder ObjectFolder { get; set; }
public virtual ICollection<XAdditionalObjectData> AdditionalObjectData { get; set; }
}
XObjectFolder:
[Table("tbl_object_folders")]
public class XObjectFolder
{
[Column("id")]
public int Id { get; set; }
[Column("display_name")]
public String DisplayName { get; set; }
[Column("short_name")]
public String ShortName { get; set; }
[Column("ref_parent_folder")]
public virtual XObjectFolder ParentFolder { get; set; }
public virtual ICollection<XObjectFolder> ChildFolders { get; set; }
public virtual ICollection<XObject> Objects { get; set; }
[NotMapped]
public int ParentFolderId { get { return ParentFolder == null ? -1 : ParentFolder.Id; } }
}
As you've probably already seen, an object folder can contain subfolders but also objects.
My goal is to see this as one "datasource" in my treelist.
For example like this:
Object Folder A
Object Sub-Folder A
Object 1
Object 1
In other questions here I've found the possibilities to concat or union queryables, but that only works with them being the same type:
using (var db = new XDbContext(_conString))
{
// Queryables
var ofs = from of in db.ObjectFolders orderby of.DisplayName ascending select of; // <- All ObjectFolders
var obs = from obj in db.Objects orderby obj.DisplayName ascending select obj; // <- All Objects
// Concat them
var comb = ofs.Concat(obs); // <- not the same type
// As DataSource for my TreeList
TreeListObjects.DataSource = comb.ToList();
}
Which is why I am searching for a good way to make this possible.
I could also imagine me using a pretty bad approach to reach my goal. So I am open to suggestions. This is a personal project which I do to improve myself at stuff.
Thanks in advance!
EDIT
So I managed to get a step further by using an interface both classes share:
public interface ITreeListCombinable
{
int Id { get; set; }
int ParentId { get; }
String DisplayName { get; set; }
}
But... who would've thought... there occures another problem:
Have a look at the db structure:
Db_Struture
Since both objects are stored in different tables, the id's will certainly not be unique when combining them.
Which is necessary when setting the datasource.
Solution:
So I've taken my own approach to my problem and it worked out.
Full disclosure -> I consider myself a beginner, so this solution is probably not the best. Still, if anyone is in a similar situation, here's how it could work:
First I created an interface, which both the folder and objects share:
ITreeListCombinable
public interface ITreeListCombinable
{
int Id { get; set; }
int ParentId { get; }
int ListId { get; set; }
int ParentListId { get; set; }
String DisplayName { get; set; }
ObjectTreeListElementTypes TreeListElementType { get; }
}
I then made sure, both my XObject and XObjectFolder classes held the ObjectTreeListElementTypes value they're corresponding to:
ObjectTreeListElementTypes Enum:
public enum ObjectTreeListElementTypes
{
Folder,
Object
}
Classes:
[NotMapped]
public ObjectTreeListElementTypes TreeListElementType => ObjectTreeListElementTypes.Folder; // or *.Object for that matter
So afterwards I've wrote my own "controller" which handles my specific scenario.
ObjectTreeListElementController:
public class ObjectTreeListElementController
{
private List<ITreeListCombinable> _list;
public ObjectTreeListElementController()
{
_list = new List<ITreeListCombinable>();
}
public void AddRange(List<ITreeListCombinable> list)
{
// add incoming items to private _list
_list.AddRange(list);
}
public List<ITreeListCombinable> GetDataSourceList()
{
// create auto increment list id
var listId = 0;
foreach (var item in _list)
{
item.ListId = listId;
listId++;
}
// set new parent list id according to incremental list id
foreach (var item in _list)
{
var parents = _list.Where(x => x.Id == item.ParentId && x.TreeListElementType == ObjectTreeListElementTypes.Folder);
if (parents.Count() > 0)
item.ParentListId = parents.First().ListId;
else
item.ParentListId = -1;
}
return _list;
}
}
Essentially, when calling the GetDataSourceList() method, it firstly distributes incremental, temporary list-ids.
In a second loop I then search for the original parent id and match the tree list element type. If none is found, this folder is a root folder in my treelist, if one is found, the given list-id becomes the parent list id:
using (var db = new XDbContext(_conString))
{
// Queryables
IQueryable<ITreeListCombinable> ofs = from of in db.ObjectFolders orderby of.DisplayName ascending select of;
IQueryable<ITreeListCombinable> objs = from obj in db.Objects orderby obj.DisplayName ascending select obj;
var lofs = ofs.ToList();
var lobjs = objs.ToList();
var ctrl = new ObjectTreeListElementController();
ctrl.AddRange(lofs);
ctrl.AddRange(lobjs);
var sourceList = ctrl.GetDataSourceList();
// As DataSource for my TreeList
TreeListObjects.DataSource = sourceList;
}
And this brought me the exact output I've wanted:
Hope this helps another beginner :)

EF Core Include() doesn't query all childs

I have this model:
public class RepairRequest
{
[Key]
public int Id { get; set; }
public List<RepairAction> RepairActions { get; set; }
public decimal TotalPrice => RepairActions.Sum(r => r.ActionPrice);
public string LastOperation => RepairActions.LastOrDefault().RepairOperation.Description;
}
public class RepairAction
{
[Key]
public int Id { get; set; }
public int RepairRequestId { get; set; }
public RepairRequest RepairRequest { get; set; }
public int RepairOperationId { get; set; }
public RepairOperation RepairOperation { get; set; }
public decimal ActionPrice { get; set; }
}
public class RepairOperation
{
[Key]
public int Id { get; set; }
public string Description { get; set; }
}
I'm trying to query RepairRequests and get TotalPrice and also LastOperation in a List but doesn't work for both properties. This is what I have tried till now:
using (var context = new ServiceManagerContext(new DbContextOptions<ServiceManagerContext>())) {
var data = context.RepairRequests
.Include(r => r.RepairActions).ThenInclude(r => r.RepairOperation); // Only LastAction works
//.Include("RepairActions").Include("RepairActions.RepairOperation"); // Only LastAction works
//.Include(r => r.RepairActions); // Only TotalPrice works
//.Include("RepairActions"); // Only TotalPrice works
var repairRequest = data.FirstOrDefault(r => r.Id == 5);
Assert.NotNull(repairRequest);
Assert.Equal(60.0m, repairRequest.RepairPrice);
Assert.Equal("Παραδόθηκε", repairRequest.LastAction);
}
Thank you.
I'd consider avoiding attempting to resolve calculated properties in your domain entities and instead look to resolve those when querying the data to populate view models.
If your view model needs the TotalPrice and LastOperation, then provided a Repository or such returning IQueryable you can expand the query to return what is needed using deferred execution rather than attempting to rely on eager loading the entire tree:
I.e.
IQueryable<RepairRequest> requests = context.RepairRequests.Where(x => x.Id == 5); // Or pull from a Repository returning the IQueryable
var viewModelData = requests.Select(x => new {x.Id, TotalPrice = x.RepairActions.Sum(), LastOperation = x.RepairActions.LastOrDefault()?.RepairOperation?.Description }).SingleOrDefault();
This should execute a more optimized query and return you an anonymous type with just the data you need to populate whatever view model you want to display. The iffy bit is around situations where there are no repair actions, or a repair action without an operation.. EF should avoid the null ref and just return null. the ?. syntax may not be necessary or supported, so it may just need to be ".". Using a method where you eager or lazy load those related entities and execute Linq off the entity instances, be careful around .SingleOrDefault() and drilling down into child fields.
Firstaball you have to declare Foreign Keys, and flag virtual properties like :
public class RepairRequest
{
[Key]
public int Id { get; set; }
public virtual ICollection<RepairAction> RepairActions { get; set; }
public decimal TotalPrice => RepairActions.Sum(r => r.ActionPrice);
public string LastOperation => RepairActions.LastOrDefault().RepairOperation.Description;
}
public class RepairAction
{
[Key]
public int Id { get; set; }
public decimal ActionPrice { get; set; }
public int RepairRequestId { get; set; }
[ForeignKey("RepairRequestId ")]
public virtual RepairRequest RepairRequest { get; set; }
public int RepairOperationId { get; set; }
[ForeignKey("RepairOperationId")]
public RepairOperation RepairOperation { get; set; }
}
Then you could call this, which load all children values :
var data = context.RepairRequests.Include("RepairActions.RepairOperation");

How to join two model and display them in view in mvc 3.0 EF 5

I have two tables which have primary and foriegn key concept. I want to get the combined data on behalf of those keys. i don't know how to bind both the table into single model and display it into view.
Model
public class TVSerialModel
{
public Int32 Serial_ID { get; set; } // primary key
public string Serial_Name { get; set; }
public int? Release_Year { get; set; }
}
public class TVSerialEpisodeModel
{
public Int64 Video_ID { get; set; }
public Int32 Serial_ID { get; set; }// foriegn key
public string Episode_Name { get; set; }
public string Description { get; set; }
public DateTime Uploaded_Time { get; set; }
}
public class TVSerial_Episode_VM
{
public IEnumerable<TVSerialEpisodeModel> tvserialEpisode { get; set; }
public IEnumerable<TVSerialModel> Tvserial { get; set; }
}
Controller
public ActionResult NewEpisodeReleased()
{
cDBContext tvContext = new cDBContext();
TVSerial_Episode_VM tves=new TVSerial_Episode_VM();
tves= tvContext.dbTvSerialEpisodes.
Join(tvContext.dbTvSerials, p => p.Serial_ID, r => r.Serial_ID,(p, r) => new { p, r }).
Select(o => new TVSerial_Episode_VM
{ ****what should i write here to get all columns from both table**** }).
Take(9).ToList();
return View(tves);
}
Expected Result
If TVSerialEpisode has a property TVSerial, you can just dot through your foreign keys.
cDBContext.dbTvSerialEpisode
.Select(t =>
new {
t.TVSerial.Serial_ID,
t.TVSerial.Serial_Name,
t.Episode_Name
})
.Take(9)
.ToList();
You need to improve little bit the models you used with EF. You must include the reference object in model.
Like this
public virtual TVSerialModel TVSerialModel { get; set; }
in main table. This way you can select referred table too.
EF Include
public ActionResult NewEpisodeReleased()
{
cDBContext tvContext = new cDBContext();
TVSerial_Episode_VM tves=new TVSerial_Episode_VM();
tves= tvContext.dbTvSerialEpisodes.Include("TVSerialEpisodeModel")
.Include("TVSerialModel").ToList();
return View(tves);
}

EF Code first join based on a range

I am using EF v6 Code First against an existing SQL DB (so the schema is fairly fixed).
I need to build a model for the following classes and wanted to know if there is a was a way to map a relationship between a Reading and a TemperatureCategory where the Reading's temperature falls between the lower and upper bounds of the TemperatureCategory?
public class Reading
{
public int Id { get; set; }
...
public double Temperature { get; set; }
...
public virtual TemperatureCategory Category { get; set; }
}
public class TemperatureCategory
{
public int Id { get; set; }
public string Description { get; set; }
public double LowerBound { get; set; }
public double UpperBound { get; set; }
...
}
Many thanks
It's an interesting idea, but no, you can't. Joins are always based on equality.
So you have to query the TemperatureCategory. For instance
from r in context.Readings
let category = context.TemperatureCategories
.FirstOrDefault(c => c.LowerBound < r.Temperature
&& c.UpperBound >= r.Temperature)
select new { Reading = r, Category = category.Description }

Eager loading including navigational property of derived class

Sample class structure
class Order
{
public int Id { get; set; }
public DateTime Date { get; set; }
public List<OrderDetail> Details { get; set; }
}
class OrderDetail
{
public int Id { get; set; }
public int Qty { get; set; }
public Item Item { get; set; }
}
class Item
{
public int Id { get; set; }
public string Name { get; set; }
}
class ElectronicItem : Item
{
public MoreDetail Detail { get; set; }
}
class MoreDetail
{
public int Id { get; set; }
public string SomeData { get; set; }
}
In order to populate order object with all navigational properties, I wrote
context.Orders.Include("Details").Include("Details.Item")
I also want to load MoreDetail object, hence I tried
context.Orders.Include("Details").Include("Details.Item.Detail")
It didn't work. How to load complete Order object?
It is currently not possible but it is feature requested by community on User DataVoice as you already found. There is also related bug on MS Connect.
You simply cannot eager load navigation properties of derived types but you can load them with separate query:
var moreDetails = context.MoreDetails;
EF should automatically fix your navigation properties. If you use filtering on orders in your original query you must apply that filter in more details query as well:
var moreDetails = cotnext.MoreDetials.Where(m => m.Item.Order ....);