entity-framework

问题 I'm new to MVC and EF code first. I'm in struggle to model a real-estate company DB model using EF code-first approach and I did some exercises as well as reading some online tutorials. First thing I have a customers table that would be in relation with one or more properties he/she has registered as it's owner to sell or to rent, I was wondering if it is possible to have some sub classes inside a model class for registered properties as below: public Property { public int PropertyID { get;

问题 This question already has answers here : LINQ to Entities does not recognize the method (4 answers) Closed 2 years ago . //Delete Last Record which has income var itemToRemove = db.People.LastOrDefault(p => p.Incomes.Any()); db.Incomes.RemoveRange(itemToRemove.Incomes); db.People.Remove(itemToRemove); it gives me this error An unhandled exception of type 'System.NotSupportedException' occurred in EntityFramework.SqlServer.dll Additional information: LINQ to Entities does not recognize the

问题 This question already has answers here : LINQ to Entities does not recognize the method (4 answers) Closed 2 years ago . //Delete Last Record which has income var itemToRemove = db.People.LastOrDefault(p => p.Incomes.Any()); db.Incomes.RemoveRange(itemToRemove.Incomes); db.People.Remove(itemToRemove); it gives me this error An unhandled exception of type 'System.NotSupportedException' occurred in EntityFramework.SqlServer.dll Additional information: LINQ to Entities does not recognize the

问题 I am trying to filter a model with two dropdown in an MVC project var model = (from x in db.TABLE.... join y in db.TABLE...).Where(where)... my logic is String where = string.Empty; if (search.anno != null) where = " ANNO = " + search.anno ; if (search.Cliente != null) { if (!string.IsNullOrEmpty(where)) { where += " And CODICE_CLIENTE = '" + search.Cliente + "'"; } else { where = " CODICE_CLIENTE = '" + search.Cliente + "'"; } } i get an error: System.Linq.Dynamic.ParseException: Character

问题 My model classes are: public class User { public User() { Polls = new List<Poll>(); } public int Id { get; set; } public String FirstName { get; set; } public String LastName { get; set; } ICollection<Poll> Polls { get; set; } } public class Poll { public int Id { get; set; } public int PositiveCount { get; set; } public int NegativeCount { get; set; } public String Description { get; set; } public User User { get; set; } } public class PollsContext : DbContext { public DbSet<User> Users {

问题 Given the following two example C# entity classes ... class EntityA { public int EntityAId { get; set; } public virtaul ICollection<EntityB> Bs { get; set; } } class EntityB { public int EntityBId { get; set; } public string Foobar { get; set; } public virtual EntityA A { get; set; } } How would I go about using Entity Framework + LINQ to query for all EntityA that contain any EntityB within a provided collection of EntityB ? To clarify, if I have the following subset of EntityB ... var bs =

问题 I m getting this Exception-"The relationship between the two objects cannot be defined because they are attached to different ObjectContext objects." I ve user table and country table. The countryid is referred in user table. I am getting the above Exception when I am trying to add entry in user table. This is my code- using (MyContext _db = new MyContext ()) { User user = User .CreateUser(0, Name, address, city, 0, 0, email, zip); Country country = _db.Country.Where("it.Id=@Id", new

问题 In EF Core, there is a neat way to perform entity validation using IValidatableObject . During validation I have the current value, but I also need access to the original value. This is the validation method: public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) { } Is there some way to get access to the object's original values as well? I think the key is in ValidationContext but I'm not sure how. 来源： https://stackoverflow.com/questions/41771376/how-do-i-get-a

问题 I have inherited a sql server database and an ASP.Net MVC 4 web application which is using Entity Framework 5.0 Code First with Auto Migrations . However, it appears the previous developer forgot to add a Primary Key to one of the tables. I am now trying to do this using Auto Migrations , however, it is not working, no errors either, just seems to be ignoring the command. The table is like this public int CourseDateHistoryID { get; set; } public int CourseDateID { get; set; } public int Event

问题 How is it possible to filter data based on some set of filters or expressions that should be used with or operation in where clause? For example, there is a class: class DTOFilter { public string Domain { get; set; } public string Mobile { get; set; } } It is required to filter Users list based on the list of the filters next way: u=> (u.Email.Contains(filters[0].Domain) && u.PhoneNumber.StartsWith(filters[0].Mobile)) || (u.Email.Contains(filters[1].Domain) && u.PhoneNumber.StartsWith(filters