.NET核心实体框架mysql-字符串字段仅存储255个符号

Question

我正在使用.NET Core，Entity Framework和MySQL 5.7，在Windows上使用Visual Studio 2015创建一个应用程序。使用EF应用程序应用程序。我的数据模型由具有ID（INT）和Body（String）字段的单一类型，文章组成。当我创建数据库执行时：

> dotnet ef migrations add initial_migration
> dotnet ef database update

然后，我的数据模型的字符串字段（Article.body）在数据库中获取VARCHAR（255），无论我在列属性[Column(TypeName = "TEXT")]中设置了什么，VARCHAR（1000）也无法正常工作。因此，如果我节省了一些长字符串，则将其截断为255个字符。

此外，如果我转到数据库设置并更改Body列以在MySQL Workbench中键入文本，则仍将字符串截断为255个字符。我在做什么错？

为了简单起见

program.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Infrastructure;
using MySQL.Data.EntityFrameworkCore.Extensions;
using System;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.Linq;
using System.Threading.Tasks;
namespace netcore
{
    public class Program
    {
        public static void Main(string[] args)
        {
            ArticlesContext context = ArticlesContext.Create();
            Article a = new Article();
            a.Body = @"If one puts some long string here, than only first 255 characters will be saved.";
            context.Add(a);
            context.SaveChanges();
        }
    }
    // DB Context
    public class ArticlesContext : DbContext
    {
        private static string _conStr = @"server=localhost;userid=sevka;pwd=12321;port=3306;database=netcore;sslmode=none;";
        public ArticlesContext() : base() { }
        public ArticlesContext(DbContextOptions<ArticlesContext> options)
        : base(options)
        { }
        public static ArticlesContext Create()
        {
            var optionsBuilder = new DbContextOptionsBuilder<ArticlesContext>();
            optionsBuilder.UseMySQL(_conStr);
            //Ensure database creation
            var context = new ArticlesContext(optionsBuilder.Options);
            context.Database.EnsureCreated();
            return context;
        }
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseMySQL(_conStr);
        }
        public DbSet<Article> Articles { get; set; }
    }
    public class Article
    {
        public int ID { get; set; }
        [Column(TypeName = "TEXT")]
        public string Body { get; set; }
    }
}

project.json

{
  "dependencies": {
    "Microsoft.NETCore.App": {
      "version": "1.0.1",
      "type": "platform"
    },
    "Microsoft.ApplicationInsights.AspNetCore": "1.0.0",
    "Microsoft.AspNetCore.Diagnostics": "1.0.0",
    "Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore": "1.0.0",
    "Microsoft.AspNetCore.Identity.EntityFrameworkCore": "1.0.0",
    "Microsoft.EntityFrameworkCore.Tools": {
      "version": "1.0.0-preview2-final",
      "type": "build"
    },
    "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0",
    "Microsoft.Extensions.Configuration.Json": "1.0.0",
    "Microsoft.Extensions.Logging": "1.0.0",
    "Microsoft.Extensions.Logging.Console": "1.0.0",
    "Microsoft.Extensions.Logging.Debug": "1.0.0",
    "Microsoft.Extensions.Options.ConfigurationExtensions": "1.0.0",
    "MySQL.Data.Core": "7.0.4-IR-191",
    "MySql.Data.EntityFrameworkCore": "7.0.6-IR31"
  },
  "tools": {
    "Microsoft.EntityFrameworkCore.Tools": "1.0.0-preview2-final",
  },
  "frameworks": {
    "netcoreapp1.0": {
      "imports": [
        "dotnet5.6",
        "portable-net45+win8"
      ]
    }
  },
  "buildOptions": {
    "emitEntryPoint": true,
    "preserveCompilationContext": true
  },
  "runtimeOptions": {
    "configProperties": {
      "System.GC.Server": true
    }
  }
}

Answer 1

根据您的反馈，您需要使用流利的API代替数据注释，因为我知道最好在EF Core中使用Fluent API，这可能会在以后的版本中更改。

在您的DB上下文中，您可以为您的实体设置映射，类似的内容：

protected override void OnModelCreating(ModelBuilder modelBuilder)
{
  var entity = modelBuilder.Entity<Entity>();
  entity.Property(p => p.Body).HasColumnType("text");
  base.OnModelCreating(modelBuilder);
}

如果您想拥有一个更时尚的实体映射，则可以潜入本教程：使用ASP.NET Core Template Pack在VS 2015中创建Angular2应用程序，此教程适用于具有SQL Server的EF Core，但也适用于MySQL。