Develop Reference

The expected type was 'System.Nullable`1[System.Guid]' but the actual value was null

An exception occurred while reading a database value for property 'EMWH.UniqueAttchID'. The expected type was 'System.Nullable`1[System.Guid]' but the actual value was null.
I'm using EFCore 5.0 and I get the error listed above. If in my EMWH view I hide all records where there is a NULL in UniqueAttchID it works fine. But I can't seem to find a way to exclude the records where the principal key (for the relationship) is NULL. But still have the ability to view all records.
Code causing the error
var workOrder = await _context.EMWHs.AsNoTracking()
.Include(x => x.EMWIs).ThenInclude(x => x.HQATs)
.Where(x => x.KeyID == WorkOrderKeyId).SingleOrDefault();
EMWH
public class EMWH
{
public byte EMCo { get; set; }
public string WorkOrder { get; set; }
public string Equipment { get; set; }
public string? Description { get; set; }
public Guid? UniqueAttchID { get; set; }
[Column("udServiceRecordYN")]
public string? ServiceRecordYN { get; set; }
public char Complete { get; set; }
public long KeyID { get; set; }
[Column("DateSched")]
[Display(Name = "Scheduled Date")]
public DateTime ScheduledDate { get; set; }
public virtual EMEM EMEM { get; set; }
public virtual IEnumerable<EMWI> EMWIs { get; set; }
public virtual IEnumerable<HQAT> HQATs { get; set; }
}
HQAT
public class HQAT
{
public byte HQCo { get; set; }
public string FormName { get; set; }
public string KeyField { get; set; }
public string Description { get; set; }
public string AddedBy { get; set; }
public DateTime? AddDate { get; set; }
public string DocName { get; set; }
public int AttachmentID { get; set; }
public string TableName { get; set; }
public Guid? UniqueAttchID { get; set; }
public string OrigFileName { get; set; }
public string DocAttchYN { get; set; }
public string CurrentState { get; set; }
public int? AttachmentTypeID { get; set; }
public string IsEmail { get; set; }
public long KeyID { get; set; }
public virtual udEMCD EMCD { get; set; }
public virtual HQAF HQAF { get; set; }
public virtual EMWH EMWH { get; set; }
public virtual EMWI EMWI { get; set; }
public virtual udEMED EMED { get; set; }
}
DBContext
modelBuilder.Entity<EMWH>().ToTable("EMWH").HasKey(k=>new { k.EMCo, k.WorkOrder });
modelBuilder.Entity<HQAT>().HasOne(x => x.EMWH).WithMany(x => x.HQATs).HasForeignKey(x => x.UniqueAttchID)
.HasPrincipalKey(x => x.UniqueAttchID);

You have the relationship set up to count on public Guid? UniqueAttchID { get; set; } for keys between entities, but you have this set up as a nullable GUID type, so when the query runs the DB is likely coming across a null value in the table, and can't resolve the relationship. The simple solution and arguably best practice is to make those properties non-nullable, or define the relationship using int or long types as ID's, so they can't be null, and making sure your INSERT and UPDATE queries are properly setting the relationships. Either way, the null is where you should start and if you have records in the tables already that have null values you are expecting to use as keys, you could have some work on your hands to figure out how those are supposed to be linked and getting the nulls replaced with GUID values.

Map two lists to parent class and nested class

I have two lists, list of Accounts and list of Transactions that represent below model. Let's assume they look like this:
List<Response.Account> accounts;
List<Response.Transaction> transactions;
And the model:
public class Response
{
public List<Account> Accounts { get; set; } = new List<Account>();
public class Account
{
public string AccountNumber { get; set; }
public long AvailableCredit { get; set; }
public double Balance { get; set; }
public long? CertainDate { get; set; }
public string CredentialsId { get; set; }
public string Id { get; set; }
public string Name { get; set; }
public string Type { get; set; }
public string UserId { get; set; }
public bool Closed { get; set; }
public List<Transaction> Transactions { get; set; } = new List<Transaction>();
}
public class Transaction
{
public string AccountId { get; set; }
public long Amount { get; set; }
public string CategoryId { get; set; }
public string CredentialsId { get; set; }
public long Date { get; set; }
public string Description { get; set; }
public string FormattedDescription { get; set; }
public string Id { get; set; }
public long Inserted { get; set; }
public long LastModified { get; set; }
public long OriginalAmount { get; set; }
public long OriginalDate { get; set; }
public string OriginalDescription { get; set; }
public long Timestamp { get; set; }
public string Type { get; set; }
public string UserId { get; set; }
}
}
To each Account class in Response class I want to assign a list of transactions by mapping Id from Account class and AccountId from Transaction class. I am aware I could do that by iterating over Accounts or Transactions and checking if both ids are equal and then assign to proper collection but that would cause nested iterations and I am not sure about its efficiency. What should I do? The only contraints in this model are those two lists in the beggining.

Save complexa data using entity framework

Hi every one I want to save complex data using Entity Framework and C#. I have 2 classes Product and Order defined as follows
Product Class
public class Product
{
[Key]
public int Id { get; set; }
public string SKU_Code { get; set; }
public string Product_Name { get; set; }
public string Quantity { get; set; }
public string Price { get; set; }
public string Image { get; set; }
public DateTime Created_Date { get; set; }
public DateTime Modified_Date { get; set; }
}
Order Class
public class Order
{
[Key]
public long ID { get; set; }
public string Order_Id { get; set; }
public string Payment_Type { get; set; }
public string Customer_Name { get; set; }
public string Shipping_Address { get; set; }
public DateTime Order_Date { get; set; }
public DateTime Modified_Date { get; set; }
public bool Flag { get; set; }
public List<Product> ProductDetails { get; set; }
}
And I want to save data Order details and my piece of code is as follows.
public Order Add(Order odrerDetails)
{
using (var context = new EcommerceDBContext())
{
var MyOrder_Id = Helper.Random(7); //Generate random orderID from my class
foreach (var detail in odrerDetails.ProductDetails)
{
odrerDetails.Order_Id = MyOrder_Id;
odrerDetails.Quantity = Convert.ToInt32(detail.Quantity);
odrerDetails.Amount = Convert.ToDouble(detail.Price);
//Other Details
context.objOrderListing.Add(odrerDetails);
}
context.SaveChanges();
return odrerDetails;
}
}
This gives me perfect data but when it comes to context.SaveChanges(); it return's me error.
An error occurred while saving entities that do not expose foreign key properties for their relationships. The EntityEntries property will return null because a single entity cannot be identified as the source of the exception. Handling of exceptions while saving can be made easier by exposing foreign key properties in your entity types.

To me you domain model seems all wrong. The order should just be used for grouping, its a typical e-commerce scenario.
When you get a receipt of your purchases, you get one receipt with every Item and price listed next to it. Its considered as one order of multiple things, not multiple orders of multiple things.
Reading your last comment, you cant have multiple orders with the same order id. Try to understand the domain first before trying to solve it with code. Also,you have no notion of a Customer with an Order.
public class Product
{
[Key]
public int Id { get; set; }
public string SKU_Code { get; set; }
public string Product_Name { get; set; }
public string Price { get; set; }
public string Image { get; set; }
public DateTime Created_Date { get; set; }
public DateTime Modified_Date { get; set; }
}
public class Order
{
[Key]
public long ID { get; set; }
public string Order_Id { get; set; }
public string Payment_Type { get; set; }
public string Customer_Name { get; set; }
public string Shipping_Address { get; set; }
public DateTime Order_Date { get; set; }
public DateTime Modified_Date { get; set; }
public bool Flag { get; set; }
public List<OrderLineItem> Items { get; set; }
}
public class OrderLineItem
{
[Key]
public long ID { get; set; }
public long Order_Id { get; set; }
public long Product_Id {get; set;}
public int Quantity {get; set;}
}

How to query IDBSet via linq

I have a table that i am attempting to query in order to create a menu. I am also querying the related tables to pair down result. I have a models project that contains all of my data models. In my Entities file I have
public IDbSet<Agent> Agents { get; set; }
public IDbSet<UsersLogin> UsersLogins { get; set; }
public IDbSet<Role> Roles { get; set; }
public IDbSet<UserRoleMapping> UserRoleMappings { get; set; }
public IDbSet<Qualifier> Qualifiers { get; set; }
public IDbSet<tblMenus> tblMenu { get; set; }
public IDbSet<tblUserMenuMapping> tblUserMenuMappings { get; set; }
public IDbSet<tblRoleMenuMapping> tblRoleMenuMappings { get; set; }
In my Interface i have ICollection<tblMenus> GetAllMenus();
Then i have my linq query which pares everything down and returns main menus and child menus.
public ICollection<tblMenus> GetAllMenus()
{
if (Global.CurrentProfile.UserID == 1)
{
return DataAccess.tblMenu.Where(m => !m.IsDeleted).ToList();
}
else
{
var UserInfo = GetUserInfo();
UserType = UserInfo.First().UserTypeID;
var childRoleMenus =
from menus in DataAccess.tblMenu
join roleMenus in DataAccess.tblRoleMenuMappings on menus.MenuID equals roleMenus.MenuID
join userRoles in DataAccess.UserRoleMappings on roleMenus.RoleID equals userRoles.RoleID
where userRoles.UserID == Global.CurrentProfile.UserID && !menus.IsDeleted
select menus;
var userChildMenus =
from menus in DataAccess.tblMenu
join userMenus in DataAccess.tblUserMenuMappings on menus.MenuID equals userMenus.MenuID
where userMenus.UserID == Global.CurrentProfile.UserID
select menus;
var childMenus = childRoleMenus.Union(userChildMenus).ToList();
However when i execute the query in my page it returns this error.
The specified type member 'MenuID' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported
Here are my models.
public class tblMenus : ModelBase
{
public int MenuID { get; set; }
public string MenuName { get; set; }
public string MenuLink { get; set; }
public Nullable<int> ParentID { get; set; }
public Nullable<bool> IsParent { get; set; }
public string IconImagePath { get; set; }
public Nullable<int> ApplicationID { get; set; }
public int CreatedBy { get; set; }
public System.DateTime CreatedOn { get; set; }
public string UpdatedBy { get; set; }
public Nullable<System.DateTime> UpdatedOn { get; set; }
public bool IsDeleted { get; set; }
public string ProcessedPage { get; set; }
public string MenuTarget { get; set; }
public Nullable<bool> IsEnabled { get; set; }
public string MenuCategory { get; set; }
public int MenuOrder { get; set; }
public virtual ICollection<tblRoleMenuMapping> tblRoleMenuMapping { get; set; }
public int RoleMenuID { get; set; }
public int RoleID { get; set; }
public int MenuID { get; set; }
public int CreatedBy { get; set; }
public System.DateTime CreatedOn { get; set; }
public Nullable<int> UpdatedBy { get; set; }
public Nullable<System.DateTime> UpdatedOn { get; set; }
public Nullable<bool> IsDeleted { get; set; }
public string ProcessedPage { get; set; }
public string PageAccessibility { get; set; }
public virtual ICollection<tblMenus> tblMenus { get; set; }
public virtual ICollection<Role> Role { get; set; }
public class tblUserMenuMapping : ModelBase
{
public int UserMenuID { get; set; }
public int UserID { get; set; }
public int MenuID { get; set; }
public Nullable<int> CreatedBy { get; set; }
public Nullable<System.DateTime> CreatedOn { get; set; }
public Nullable<int> UpdatedBy { get; set; }
public Nullable<System.DateTime> UpdatedOn { get; set; }
public bool IsDeleted { get; set; }

It's hard to say for sure without seeing the whole of both model classes and your database. Some things to check are:
Verify each respective 'MenuID' column exist in each underlying table. Because you aren't using mapping configurations, you need to make sure the column names follow the convention naming EF expects.
Verify their is a foreign key relationship between the two tables.
From a more general perspective, I would consider using configuration classes so your relationships are explicit and your model is more easily changed from the tables they map to.
Finally, you may see some clues by inspecting the SQL that EF has generated. Use the technique described in this post for any red flags (like EF is looking for a column that doesn't exist):
var result = from x in appEntities
where x.id = 32
select x;
var sql = ((System.Data.Objects.ObjectQuery)result).ToTraceString();

ASP.Net MVC 5 EF6 - Allow nullables on two properties but force at least one to be present

In simple relational terms, I want each entry of ContractDetails to be assigned to either a Site OR a Company, not both at the same time, and one of them must be selected or there is no link at all. I'm not quite sure how to represent this in entity framework. My Model at Present:
Company Model:
public class Company
{
public int ID { get; set; }
public string Company_Name { get; set; }
public string Company_Prefix { get; set; }
public virtual ICollection<Site> Sites { get; set; }
}
Contract Details Model:
public class ContractDetails
{
public int ContractDetailsID { get; set; }
public int ContractTypeID { get; set; }
public int ContractRenewalPeriodID { get; set; }
public int? CompanyID { get; set; }
public int? SiteID { get; set; }
[Required, StringLength(10)]
public string Reference { get; set; }
[Display(Name = "Contract Start Date"), DataType(DataType.Date)]
public DateTime? Contract_Start_Date { get; set; }
[Display(Name = "Contract End Date"), DataType(DataType.Date)]
public DateTime? Contract_End_Date { get; set; }
[Column(TypeName = "text")]
public string Notes { get; set; }
public string Direct_Debit_Reference { get; set; }
public virtual Company Company { get; set; }
public virtual Site Site { get; set; }
public virtual ContractType ContractType { get; set; }
public virtual ContractRenewalPeriod ContractRenewalPeriod { get; set; }
}
Site Model:
public class Site
{
public int ID { get; set; }
public string Site_Name { get; set; }
public string Site_TelephoneNumber { get; set; }
public string Site_City { get; set; }
public int CompanyID { get; set; }
public virtual Company Company { get; set; }
}

Just implement the IValidatableObject on ContractDetails class. On Validate method put the validation logic. If the object is not valid you must return a collection of ValidationResult. when saving the object, EF will execute the Validate method and verify that your ContractDetails object is coherent.