entity-framework-core-2.2

问题 I am using Entity Framework Core in my .NET Core console app. I store my connection string in the App.config file and use ConfigurationManager in context class to access the connection string. When I want to add new migration to my project I get the following error: System.NullReferenceException: Object reference not set to an instance of an object. at EF_tut.Context.OnConfiguring(DbContextOptionsBuilder optionsBuilder) in C:\..\Context.cs:line 12 at Microsoft.EntityFrameworkCore.DbContext

来源： https://stackoverflow.com/questions/59633711/ef-core-update-object-graph-duplicates-child-entities

来源： https://stackoverflow.com/questions/59633711/ef-core-update-object-graph-duplicates-child-entities

问题 I have an ASP .Net Core 2.2 Web API. In one of my controller actions, I am adding a bunch of rows to a MySQL database table (I'm using Pomelo). So for example: _dbContext.AddRange(entities); _dbContext.SaveChanges(); The entities I'm adding have two primary keys (composite primary key) and the keys are already populated in the entities collection when I add them to DbContext (i.e. I am setting the keys myself - there is no "auto increment" or anything like that where the database generates

问题 I have an ASP .Net Core 2.2 Web API. In one of my controller actions, I am adding a bunch of rows to a MySQL database table (I'm using Pomelo). So for example: _dbContext.AddRange(entities); _dbContext.SaveChanges(); The entities I'm adding have two primary keys (composite primary key) and the keys are already populated in the entities collection when I add them to DbContext (i.e. I am setting the keys myself - there is no "auto increment" or anything like that where the database generates

问题 I have an ASP .Net Core 2.2 Web API. In one of my controller actions, I am adding a bunch of rows to a MySQL database table (I'm using Pomelo). So for example: _dbContext.AddRange(entities); _dbContext.SaveChanges(); The entities I'm adding have two primary keys (composite primary key) and the keys are already populated in the entities collection when I add them to DbContext (i.e. I am setting the keys myself - there is no "auto increment" or anything like that where the database generates