entity-framework-core

问题 I am trying to migrate a Web API from .NET Core 2.2 to .NET Core 3.0 and I have stumbled across the following: public Dictionary<int, Tag> GetTagMap(IList<int> tagIds = null) { var tags = context.Tag.AsNoTracking(); if (tagIds != null) tags = tags.Where(t => tagIds.Contains(t.TagId)); return tags .ToList() // explicit client evaluation in 3.0 .ToDictionary(t => t.TagId, t => t); } This used to generate a SQL statement similar to this one: SELECT TagId, Name FROM Tag WHERE TagId IN (1, 2, 3)

问题 I am trying to migrate a Web API from .NET Core 2.2 to .NET Core 3.0 and I have stumbled across the following: public Dictionary<int, Tag> GetTagMap(IList<int> tagIds = null) { var tags = context.Tag.AsNoTracking(); if (tagIds != null) tags = tags.Where(t => tagIds.Contains(t.TagId)); return tags .ToList() // explicit client evaluation in 3.0 .ToDictionary(t => t.TagId, t => t); } This used to generate a SQL statement similar to this one: SELECT TagId, Name FROM Tag WHERE TagId IN (1, 2, 3)

问题 I'm implementing repository pattern in company solution I work for, separating model classes in a Backend project and database context and migrations in DbContexts project. I'm using Scaffold-DbContext setting my Backend Project as default project to destination of model classes, however DbContext Class is always created in same folder as model classes. Is it possible to redirect the creation of the DbContext class to a different output folder, in my case to DbContexts project? 回答1: It is now

问题 I'm trying to rewrite old library to use EntityFramework Core and I can't figure out how to begin transaction with specific isolation level. Previously I was able to do something like this: DbContext.Database.BeginTransaction(IsolationLevel.Snapshot); What is alternative implementation in the EntityFramework Core? 回答1: The EF Core code is exactly the same. DbContext.Database.BeginTransaction(IsolationLevel.Snapshot); The only difference is that in EF Core the method with isolation level (as

问题 I'm trying to rewrite old library to use EntityFramework Core and I can't figure out how to begin transaction with specific isolation level. Previously I was able to do something like this: DbContext.Database.BeginTransaction(IsolationLevel.Snapshot); What is alternative implementation in the EntityFramework Core? 回答1: The EF Core code is exactly the same. DbContext.Database.BeginTransaction(IsolationLevel.Snapshot); The only difference is that in EF Core the method with isolation level (as

问题 Please consider the following entities public class What { public int Id { get; set; } public string Name { get; set; } public ICollection<Track> Tracks { get; set; } public int? LastTrackId { get; set; }] public Track LastTrack { get; set; } } public class Track { public Track(string what, DateTime dt, TrackThatGeoposition pos) { What = new What { Name = what, LastTrack = this }; } public int Id { get; set; } public int WhatId { get; set; } public What What { get; set; } } I use the

问题 In EF Core 2.0, we have the ability to derive from IEntityTypeConfiguration for cleaner Fluent API mappings (source). How can I extend this pattern to utilize a base entity? In the example below, how can I have a BaseEntityConfiguration to reduce duplication in LanguageConfiguration and MaintainerConfiguration , modifying properties that are in the BaseEntity only in the BaseEntityConfiguration ? What would such a BaseEntityConfiguration look like; and how would it be used, if at all, in

问题 In EF Core 2.0, we have the ability to derive from IEntityTypeConfiguration for cleaner Fluent API mappings (source). How can I extend this pattern to utilize a base entity? In the example below, how can I have a BaseEntityConfiguration to reduce duplication in LanguageConfiguration and MaintainerConfiguration , modifying properties that are in the BaseEntity only in the BaseEntityConfiguration ? What would such a BaseEntityConfiguration look like; and how would it be used, if at all, in

问题 I need to execute a complex sql query in entity framework core 3.1.1, on researching i found out that keyless entity types is the way to go in code first approach. I see lot of documents for dbquery but this is marked as obsolete in .net core 3.x keyless entity types As per Microsoft documentation it says dbquery is obsolete so use dbset approach instead, but with dbset it is trying to create a new table in database. how to disable table generation in keyless entity types while applying

问题 In EF Core 2.2 I had: var data = await _ArticleTranslationRepository.DbSet .Include(arttrans => arttrans.Article) .ThenInclude(art => art.Category) .Where(trans => trans.Article != null && trans.Article.Category != null && trans.Article.Category.Id == categoryId.Value) .GroupBy(trans => trans.ArticleId) .Select(g => new { ArticleId = g.Key, TransInPreferredLang = g.OrderByDescending(trans => trans.LanguageId == lang).ThenByDescending(trans => trans.LanguageId == defaultSiteLanguage).ThenBy