使用 linq 更新复合键字段

Question

在我们的 SQL 数据库中，我们有一个带有复合键的表，其中包含我们需要不时更新的字段。据我了解，由于我们使用的是实体框架，因此我需要先从数据库中删除记录，然后再将行添加回表中。

以下是我创建的用于处理“更新”的简单方法，因为有许多方法可以执行此操作。但是，一旦在.Remove 之后调用.SaveChanges() 方法，我就会得到DbUpdateConcurrencyException：

Store update, insert, or delete statement affected an unexpected number of 
rows (0). Entities may have been modified or deleted since entities were loaded. 
Refresh ObjectStateManager entries.

不确定我做错了什么，因为我正在尝试删除记录，然后执行更新，然后重新添加记录。

这是调用删除/编辑方法的方法。调用此方法时，记录尚未以任何方式更改形状或形式。

    private static void ProcessAllChanges(ZipCodeIndex information, ZipCodeTerritory zipToUpdate)
    {
        try
        {
            RemoveRecord(zipToUpdate);

            if (!string.IsNullOrWhiteSpace(information.newTerritory)) zipToUpdate.IndDistrnId = information.newTerritory;
            if (!string.IsNullOrWhiteSpace(information.newStateCode)) zipToUpdate.StateCode = information.newStateCode;
            if (!string.IsNullOrWhiteSpace(information.newDescription)) zipToUpdate.DrmTerrDesc = information.newDescription;
            if (!string.IsNullOrWhiteSpace(information.newChannelCode)) zipToUpdate.ChannelCode = information.newChannelCode;
            if (zipToUpdate.EndDate == DateTime.MinValue) zipToUpdate.EndDate = DateTime.MaxValue;

            EditRecord(zipToUpdate);
            _updated++;   
        }
        catch (DbEntityValidationException dbEx)
        {
            _msg += "Error during update; ";
            EventLog.WriteEntry("Monet", "Error during ProcessAllChanges: " + zipToUpdate.ToString() + " |EX| " + dbEx.Message);
        }
        catch (Exception ex)
        {
            _msg += "Error during update; ";
            EventLog.WriteEntry("Monet", "Error during ProcessAllChanges: " + zipToUpdate.ToString() + " |MESSAGE| " + ex.Message);
        }
    }

这里有两个被调用的辅助方法

    public static void RemoveRecord(ZipCodeTerritory zipCode)
    {
        _db = new AgentResources();
        _db.ZipCodeTerritory.Attach(zipCode);
        _db.ZipCodeTerritory.Remove(zipCode);
        _db.SaveChanges();
    }

    public static void EditRecord(ZipCodeTerritory zipCode)
    {
        _db = new AgentResources();
        _db.ZipCodeTerritory.Add(zipCode);
        _db.SaveChanges();
    }

编辑

基于下面的几个 cmets，我尝试创建上下文对象的单独实例，但是使用此方法我收到了相同的错误：

    public static void RemoveRecord(ZipCodeTerritory zipCode)
    {
        using (AgentResources deleteMe = new AgentResources())
        {
            deleteMe.ZipCodeTerritory.Attach(zipCode);
            deleteMe.ZipCodeTerritory.Remove(zipCode);
            deleteMe.SaveChanges();                
        }
    }

二次编辑

这是调用我在上面发布的ProcessAllChanges 方法的最上面的方法。

    public static string TerritoryOnly(ZipCodeIndex updateZip)
    {
        if (!string.IsNullOrWhiteSpace(updateZip.newEffectiveDate) || !string.IsNullOrWhiteSpace(updateZip.newEndDate))
        {
            return "Neither effective or end date can be present if updating Territory Code only; ";
        }

        RefreshProperties();

        foreach (var zipCode in updateZip.displayForPaging.Where(x => x.Update))
        {
            ProcessAllChanges(updateZip, zipCode);
        }

        _msg += _updated + " record(s) updated; ";

        return _msg;
    }

第三次修改

这里的每个请求是 AgentResources 的完整类定义，我们的 DbContext 对象

namespace Monet.Models
{
    using System;
    using System.Data.Entity;
    using System.Data.Entity.Infrastructure;

    public partial class AgentResources : DbContext
    {
        public AgentResources()
            : base("name=AgentResources")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            throw new UnintentionalCodeFirstException();
        }

        public DbSet<AgentContEd> AgentContEd { get; set; }
        public DbSet<ContEdCourse> ContEdCourse { get; set; }
        public DbSet<Course> Course { get; set; }
        public DbSet<CourseToProduct> CourseToProduct { get; set; }
        public DbSet<Product> Product { get; set; }
        public DbSet<ProcessControl> ProcessControl { get; set; }
        public DbSet<AgentIdToTradingPartner> AgentIdToTradingPartner { get; set; }
        public DbSet<TradingPartner> TradingPartner { get; set; }
        public DbSet<Notes> Notes { get; set; }
        public DbSet<CourseMaterials> CourseMaterials { get; set; }
        public DbSet<TransactionLog> TransactionLog { get; set; }
        public DbSet<Agent> Agent { get; set; }
        public DbSet<AgentIdentification> AgentIdentification { get; set; }
        public DbSet<BatchDashboard> BatchDashboard { get; set; }
        public DbSet<BatchPrograms> BatchPrograms { get; set; }
        public DbSet<FollowUpItems> FollowUpItems { get; set; }
        public DbSet<sysdiagrams> sysdiagrams { get; set; }
        public DbSet<AgentProductTraining> AgentProductTraining { get; set; }
        public DbSet<Channel> Channel { get; set; }
        public DbSet<RelationshipCodes> RelationshipCodes { get; set; }
        public DbSet<DropDownValues> DropDownValues { get; set; }
        public DbSet<QueueUpdates> QueueUpdates { get; set; }
        public DbSet<MarketingLookup> MarketingLookup { get; set; }
        public DbSet<TransmissionHistory> TransmissionHistory { get; set; }
        public DbSet<AgentTransmission> AgentTransmission { get; set; }
        public DbSet<ZipCodeTerritory> ZipCodeTerritory { get; set; }
    }
}

这是ZipCodeTerritory 类

public partial class ZipCodeTerritory
{
    public string ChannelCode { get; set; } //Composite key field
    public string DrmTerrDesc { get; set; }
    public string IndDistrnId { get; set; }
    public string StateCode { get; set; } //Composite key field
    public string ZipCode { get; set; } //Composite key field
    public System.DateTime? DisplayEndDate { get; set; }
    public System.DateTime EndDate { get; set; } //Composite key field
    public System.DateTime EffectiveDate { get; set; } 
    public string LastUpdateId { get; set; }
    public Nullable<System.DateTime> LastUpdateDate { get; set; }
}

Answer 1

试试这个：

public static void RemoveRecord(ZipCodeTerritory zipCode)
{
    using(var _newdb = new AgentResources())
    {
        ZipCodeTerritory zipCodeRemove = new ZipCodeTerritory();
        zipCodeRemove.channelCode = zipCode.channelCode;
        zipCodeRemove.stateCode = zipCode.stateCode;
        zipCodeRemove.zipCode= zipCode.zipCode;
        zipCodeRemove.endDate = zipCode.endDate;

        _newdb.ZipCodeTerritory.Attach(zipCodeRemove);
        _newdb.ZipCodeTerritory.Remove(zipCodeRemove);
        //((IObjectContextAdapter)_newdb).ObjectContext.Refresh(
                                                    // RefreshMode.ClientWins
                                                    //, zipCode);
        _newdb.SaveChanges();
    }
}