entity-framework-core

问题 This seems like it would be really simple, but I cannot seem to resolve it. Using EF Core, I have a DbSet<Rule> Rules in my DbContext . public class Rule { public int Id { get; set; } public string Raw { get; set; } } I am trying to write a query where, given an IEnumerable<string> lines , give me all of the Rule s from the DbSet where its Raw value is an element in lines (exact match, not a substring of a value). For some time, I was using something like: private IQueryable<Rule>

问题 I'm getting data from db like this: Later I group them so it looks like Month 6 Week 2 Amount 228 And so on.. Here is the code: var yas = await _context.product .AsNoTracking() .Where(x => (x.PaymentDate != null && x.PaymentDate > DateTime.UtcNow.AddMonths(-4))).ToListAsync(); var grouped = yas.GroupBy(x => CultureInfo.CurrentCulture.Calendar.GetWeekOfYear(x.PaymentDate ?? DateTime.UtcNow, CalendarWeekRule.FirstDay, DayOfWeek.Monday)) .Select(product => new productsDemoObject { Week =

问题 I've a FilterAsync method to do the query with where clause and includes the navigation properties. Below is the method for the FilterAsync. public async Task<IQueryable<T>> FilterAsync<T>(Expression<Func<T, bool>> predicate, params Expression<Func<T, object>>[] includes) where T : class { return await Task.Run(() => { //Return first 250 records/objects from var query = _context.Set<T>().Where(predicate).AsQueryable().Take(250); return includes.Aggregate(query, (current, includeProperty) =>

问题 Is it possible with the fluent api to create a database generated string with specific rules? Like say: The string should start with "a" then a number that is incremented by 1 and minimum starting value is 10000. e.g. a10001, a10002,... 回答1: You could use a combination of HasSequence and HasDefaultValueSql Example works in SQL Server, not sure about other providers. public class Foo { public int FooId { get; set; } public string GeneratedString { get; set; } } public class FooContext :

问题 I need to create DbSet for my ignored entity. Now I have in my modelBuilder next code: modelBuilder.Ignore<ExtendedDepartment>(); And inside my DbSet I have: public DbSet<ExtendedDepartment> ExtendedDepartments { get; set; } When I`m trying to get data from that Dbset I have error: InvalidOperationException: Cannot create a DbSet for ExtendedDepartment because this type is not included in the model for the context. So I am trying to ignore this table in migration, maybe I am doing smthing

问题 I'm trying to null or remove the ID entirely of all the queried IsoDataTables before returning them to frontend. The idea is that it should behave (in this case) as a template and I don't want it returning the id's back to me, nor do I want them to be removed in the frontend. var applicationType = await _context.ApplicationType .Include(m => m.IsoTableData) .AsNoTracking() .FirstOrDefaultAsync(m => m.Id == id); if (applicationType == null) { return NotFound(); } if (applicationType

问题 I have an aspnetcore solution that I split into three projects: Project.Core dnxcore50 Main app - startup resides here and has Project.EF & Project.Model dependency Project.EF dotnet5.4 class libary - dbcontext resides here and has Project.Model dependency. dotnet-ef tools reside here Project.Models dotnet5.4 class library Using the dotnet cli tooling (dotnet-ef) I was able to add migrations to the project successfully. However when I execute update database to apply the migrations, I get an

问题 I am trying to find out what the authorized user is currently trying to save the data and record their email. I have a basic setup in my dbcontext that does the update for timestamps but i cannot figure out how to access the user information: public override int SaveChanges() { AddTimestamps(); return base.SaveChanges(); } public override async Task<int> SaveChangesAsync() { AddTimestamps(); return await base.SaveChangesAsync(); } private void AddTimestamps() { var entities = ChangeTracker

问题 I have the following Customer table: Id First Last LocationId 0 John Doe 2 1 Mary Smith 4 My use case requires column level permissions(predicated on a value in the Entity's table). How can I query like the following thru EFCore? SELECT Id, First, IIF(LocationId in(2), Last, '') FROM Customer; Whereby Last is returned only when LocationId == 2 . Can this be accomplished in Linq-to-Entities as a dynamic type? If not, can I use FromSql() and QueryTypes? I found this SO How to create “inline if

问题 let's say we have a Person class(with properties of Id and Age), let's say we need to change the Age of a person whose id is 1 from 29 to 30, and I use DbSet.Update() and DbSet.Attach() respectively: Person p = new Person(){ Id = 1 } var entity = context.Persons.Update(p); p.Age = 30; Console.WriteLine("entity state:" + entity.State); foreach (var modifiedProperty in entity.Properties.Where(p => p.IsModified)) { Console.Write($"The {modifiedProperty.Metadata.Name} property is marked as