Question

这两个实体是一对多的关系（由代码第一流畅的api构建）。

public class Parent
{
    public Parent()
    {
        this.Children = new List<Child>();
    }

    public int Id { get; set; }

    public virtual ICollection<Child> Children { get; set; }
}

public class Child
{
    public int Id { get; set; }

    public int ParentId { get; set; }

    public string Data { get; set; }
}

在我的WebApi控制器中，我有动作创建父实体（工作正常）并更新父实体（有一些问题）。更新操作如下所示：

public void Update(UpdateParentModel model)
{
    //what should be done here?
}

目前我有两个想法：

按existing获取名为model.Id的跟踪父实体，并将model中的值逐个分配给实体。这听起来很愚蠢。在model.Children我不知道哪个孩子是新的，哪个孩子被修改（甚至删除）。
通过model创建一个新的父实体，并将其附加到DbContext并保存。但是DbContext如何知道子项的状态（新添加/删除/修改）？

实现此功能的正确方法是什么？

Answer 1

因为发布到WebApi控制器的模型与任何实体框架（EF）上下文分离，唯一的选择是从数据库加载对象图（父级包括其子级）并比较已添加的子级，删除或更新。（除非您在分离状态（在浏览器中或在任何地方）使用您自己的跟踪机制跟踪更改，否则我认为这些更改比以下更复杂。）它可能如下所示：

public void Update(UpdateParentModel model)
{
    var existingParent = _dbContext.Parents
        .Where(p => p.Id == model.Id)
        .Include(p => p.Children)
        .SingleOrDefault();

    if (existingParent != null)
    {
        // Update parent
        _dbContext.Entry(existingParent).CurrentValues.SetValues(model);

        // Delete children
        foreach (var existingChild in existingParent.Children.ToList())
        {
            if (!model.Children.Any(c => c.Id == existingChild.Id))
                _dbContext.Children.Remove(existingChild);
        }

        // Update and Insert children
        foreach (var childModel in model.Children)
        {
            var existingChild = existingParent.Children
                .Where(c => c.Id == childModel.Id)
                .SingleOrDefault();

            if (existingChild != null)
                // Update child
                _dbContext.Entry(existingChild).CurrentValues.SetValues(childModel);
            else
            {
                // Insert child
                var newChild = new Child
                {
                    Data = childModel.Data,
                    //...
                };
                existingParent.Children.Add(newChild);
            }
        }

        _dbContext.SaveChanges();
    }
}

...CurrentValues.SetValues可以根据属性名称将任何对象和属性值映射到附加实体。如果模型中的属性名称与实体中的名称不同，则无法使用此方法，并且必须逐个分配值。

Answer 2

如果您正在使用EntityFrameworkCore，您可以在控制器后期操作中执行以下操作（Attach method递归附加导航属性，包括集合）：

_context.Attach(modelPostedToController);

IEnumerable<EntityEntry> unchangedEntities = _context.ChangeTracker.Entries().Where(x => x.State == EntityState.Unchanged);

foreach(EntityEntry ee in unchangedEntities){
     ee.State = EntityState.Modified;
}

await _context.SaveChangesAsync();

假设已更新的每个实体都具有在客户的帖子数据中设置和提供的所有属性（例如，不能用于部分更新实体）。

您还需要确保为此操作使用新的/专用实体框架数据库上下文。

Answer 3

好的，伙计们。我曾经有这个答案，但一路迷路了。当您知道有更好的方法但不记得或找不到它时，绝对折磨！非常简单我只是对其进行了多种测试。

var parent = _dbContext.Parents
  .Where(p => p.Id == model.Id)
  .Include(p => p.Children)
  .FirstOrDefault();

parent.Children = _dbContext.Children.Where(c => <Query for New List Here>);
_dbContext.Entry(parent).State = EntityState.Modified;

_dbContext.SaveChanges();

您可以用新列表替换整个列表！ SQL代码将根据需要删除和添加实体。无需为此担心。确保包括儿童收集或没有骰子。祝你好运！

Answer 4

有一些项目可以使客户端和服务器之间的交互更容易，只需要保存整个对象图。

以下是你想看的两个：

上述两个项目都会在断开的实体返回服务器时识别它们，检测并保存更改，并返回受客户端影响的数据。

Answer 5

这应该是...

private void Reconcile<T>(DbContext context,
    IReadOnlyCollection<T> oldItems,
    IReadOnlyCollection<T> newItems,
    Func<T, T, bool> compare)
{
    var itemsToAdd = new List<T>();
    var itemsToRemove = new List<T>();

    foreach (T newItem in newItems)
    {
        T oldItem = oldItems.FirstOrDefault(arg1 => compare(arg1, newItem));

        if (oldItem == null)
        {
            itemsToAdd.Add(newItem);
        }
        else
        {
            context.Entry(oldItem).CurrentValues.SetValues(newItem);
        }
    }

    foreach (T oldItem in oldItems)
    {
        if (!newItems.Any(arg1 => compare(arg1, oldItem)))
        {
            itemsToRemove.Add(oldItem);
        }
    }

    foreach (T item in itemsToAdd)
        context.Add(item);

    foreach (T item in itemsToRemove)
        context.Remove(item);
}

Answer 6

概念验证 Controler.UpdateModel无法正常使用。

全班here：

const string PK = "Id";
protected Models.Entities con;
protected System.Data.Entity.DbSet<T> model;

private void TestUpdate(object item)
{
    var props = item.GetType().GetProperties();
    foreach (var prop in props)
    {
        object value = prop.GetValue(item);
        if (prop.PropertyType.IsInterface && value != null)
        {
            foreach (var iItem in (System.Collections.IEnumerable)value)
            {
                TestUpdate(iItem);
            }
        }
    }

    int id = (int)item.GetType().GetProperty(PK).GetValue(item);
    if (id == 0)
    {
        con.Entry(item).State = System.Data.Entity.EntityState.Added;
    }
    else
    {
        con.Entry(item).State = System.Data.Entity.EntityState.Modified;
    }

}

Answer 7

@Charles McIntosh确实为我提供了答案，因为传入的模型已分离。对我来说，最终有效的方法是先保存传入的模型……然后像以前一样继续添加子代：

public async Task<IHttpActionResult> GetUPSFreight(PartsExpressOrder order)
{
    db.Entry(order).State = EntityState.Modified;
    db.SaveChanges();
  ...
}

Answer 8

public async Task<IHttpActionResult> PutParent(int id, Parent parent)
        {
            if (!ModelState.IsValid)
            {
                return BadRequest(ModelState);
            }

            if (id != parent.Id)
            {
                return BadRequest();
            }

            db.Entry(parent).State = EntityState.Modified;

            foreach (Child child in parent.Children)
            {
                db.Entry(child).State = child.Id == 0 ? EntityState.Added : EntityState.Modified;
            }

            try
            {
                await db.SaveChangesAsync();
            }
            catch (DbUpdateConcurrencyException)
            {
                if (!ParentExists(id))
                {
                    return NotFound();
                }
                else
                {
                    throw;
                }
            }

            return Ok(db.Parents.Find(id));
        }

这就是我解决此问题的方法。这样，EF知道要添加的内容进行更新。

Answer 9

对于VB.NET开发人员，使用此通用子标记易于使用的子状态

注意：


PromatCon：实体对象

amList：是您要添加或修改的子列表

rList：是您要删除的子列表

from pyspark.sql.functions import udf
from numpy import partition, arange

udf_extract_2 = udf(lambda v: (-partition(-v.toArray(), arange(N))[:N]).tolist(), 'array<double>')

(my_model.summary.predictions
    .select('prediction', udf_extract_2('probability').alias('probability'))
    .show(truncate=False))

updatechild(objCas.ECC_Decision, PromatCon.ECC_Decision.Where(Function(c) c.rid = objCas.rid And Not objCas.ECC_Decision.Select(Function(x) x.dcid).Contains(c.dcid)).toList)

Sub updatechild(Of Ety)(amList As ICollection(Of Ety), rList As ICollection(Of Ety))
        If amList IsNot Nothing Then
            For Each obj In amList
                Dim x = PromatCon.Entry(obj).GetDatabaseValues()
                If x Is Nothing Then
                    PromatCon.Entry(obj).State = EntityState.Added
                Else
                    PromatCon.Entry(obj).State = EntityState.Modified
                End If
            Next
        End If

        If rList IsNot Nothing Then
            For Each obj In rList.ToList
                PromatCon.Entry(obj).State = EntityState.Deleted
            Next
        End If
End Sub

Answer 10

var parent = context.Parent.FirstOrDefault(x => x.Id == modelParent.Id);
if (parent != null)
{
  parent.Childs = modelParent.Childs;
}

source

Answer 11

这是我的代码，效果很好。

public async Task<bool> UpdateDeviceShutdownAsync(Guid id, DateTime shutdownAtTime, int areaID, decimal mileage,
        decimal motohours, int driverID, List<int> commission,
        string shutdownPlaceDescr, int deviceShutdownTypeID, string deviceShutdownDesc,
        bool isTransportation, string violationConditions, DateTime shutdownStartTime,
        DateTime shutdownEndTime, string notes, List<Guid> faultIDs )
        {
            try
            {
                using (var db = new GJobEntities())
                {
                    var isExisting = await db.DeviceShutdowns.FirstOrDefaultAsync(x => x.ID == id);

                    if (isExisting != null)
                    {
                        isExisting.AreaID = areaID;
                        isExisting.DriverID = driverID;
                        isExisting.IsTransportation = isTransportation;
                        isExisting.Mileage = mileage;
                        isExisting.Motohours = motohours;
                        isExisting.Notes = notes;                    
                        isExisting.DeviceShutdownDesc = deviceShutdownDesc;
                        isExisting.DeviceShutdownTypeID = deviceShutdownTypeID;
                        isExisting.ShutdownAtTime = shutdownAtTime;
                        isExisting.ShutdownEndTime = shutdownEndTime;
                        isExisting.ShutdownStartTime = shutdownStartTime;
                        isExisting.ShutdownPlaceDescr = shutdownPlaceDescr;
                        isExisting.ViolationConditions = violationConditions;

                        // Delete children
                        foreach (var existingChild in isExisting.DeviceShutdownFaults.ToList())
                        {
                            db.DeviceShutdownFaults.Remove(existingChild);
                        }

                        if (faultIDs != null && faultIDs.Any())
                        {
                            foreach (var faultItem in faultIDs)
                            {
                                var newChild = new DeviceShutdownFault
                                {
                                    ID = Guid.NewGuid(),
                                    DDFaultID = faultItem,
                                    DeviceShutdownID = isExisting.ID,
                                };

                                isExisting.DeviceShutdownFaults.Add(newChild);
                            }
                        }

                        // Delete all children
                        foreach (var existingChild in isExisting.DeviceShutdownComissions.ToList())
                        {
                            db.DeviceShutdownComissions.Remove(existingChild);
                        }

                        // Add all new children
                        if (commission != null && commission.Any())
                        {
                            foreach (var cItem in commission)
                            {
                                var newChild = new DeviceShutdownComission
                                {
                                    ID = Guid.NewGuid(),
                                    PersonalID = cItem,
                                    DeviceShutdownID = isExisting.ID,
                                };

                                isExisting.DeviceShutdownComissions.Add(newChild);
                            }
                        }

                        await db.SaveChangesAsync();

                        return true;
                    }
                }
            }
            catch (Exception ex)
            {
                logger.Error(ex);
            }

            return false;
        }

Answer 12

因为我讨厌重复复杂的逻辑，所以这是Slauma解决方案的通用版本。

这是我的更新方法。请注意，在分离的情况下，有时您的代码会先读取数据然后进行更新，因此并非总是分离的。

public async Task UpdateAsync(TempOrder order)
{
    order.CheckNotNull(nameof(order));
    order.OrderId.CheckNotNull(nameof(order.OrderId));

    order.DateModified = _dateService.UtcNow;

    if (_context.Entry(order).State == EntityState.Modified)
    {
        await _context.SaveChangesAsync().ConfigureAwait(false);
    }
    else // Detached.
    {
        var existing = await SelectAsync(order.OrderId!.Value).ConfigureAwait(false);
        if (existing != null)
        {
            order.DateModified = _dateService.UtcNow;
            _context.TrackChildChanges(order.Products, existing.Products, (a, b) => a.OrderProductId == b.OrderProductId);
            await _context.SaveChangesAsync(order, existing).ConfigureAwait(false);
        }
    }
}

CheckNotNull is defined here.

创建这些扩展方法。

/// <summary>
/// Tracks changes on childs models by comparing with latest database state.
/// </summary>
/// <typeparam name="T">The type of model to track.</typeparam>
/// <param name="context">The database context tracking changes.</param>
/// <param name="childs">The childs to update, detached from the context.</param>
/// <param name="existingChilds">The latest existing data, attached to the context.</param>
/// <param name="match">A function to match models by their primary key(s).</param>
public static void TrackChildChanges<T>(this DbContext context, IList<T> childs, IList<T> existingChilds, Func<T, T, bool> match)
    where T : class
{
    context.CheckNotNull(nameof(context));
    childs.CheckNotNull(nameof(childs));
    existingChilds.CheckNotNull(nameof(existingChilds));

    // Delete childs.
    foreach (var existing in existingChilds.ToList())
    {
        if (!childs.Any(c => match(c, existing)))
        {
            existingChilds.Remove(existing);
        }
    }

    // Update and Insert childs.
    var existingChildsCopy = existingChilds.ToList();
    foreach (var item in childs.ToList())
    {
        var existing = existingChildsCopy
            .Where(c => match(c, item))
            .SingleOrDefault();

        if (existing != null)
        {
            // Update child.
            context.Entry(existing).CurrentValues.SetValues(item);
        }
        else
        {
            // Insert child.
            existingChilds.Add(item);
            // context.Entry(item).State = EntityState.Added;
        }
    }
}

/// <summary>
/// Saves changes to a detached model by comparing it with the latest data.
/// </summary>
/// <typeparam name="T">The type of model to save.</typeparam>
/// <param name="context">The database context tracking changes.</param>
/// <param name="model">The model object to save.</param>
/// <param name="existing">The latest model data.</param>
public static void SaveChanges<T>(this DbContext context, T model, T existing)
    where T : class
{
    context.CheckNotNull(nameof(context));
    model.CheckNotNull(nameof(context));

    context.Entry(existing).CurrentValues.SetValues(model);
    context.SaveChanges();
}

/// <summary>
/// Saves changes to a detached model by comparing it with the latest data.
/// </summary>
/// <typeparam name="T">The type of model to save.</typeparam>
/// <param name="context">The database context tracking changes.</param>
/// <param name="model">The model object to save.</param>
/// <param name="existing">The latest model data.</param>
/// <param name="cancellationToken">A cancellation token to cancel the operation.</param>
/// <returns></returns>
public static async Task SaveChangesAsync<T>(this DbContext context, T model, T existing, CancellationToken cancellationToken = default)
    where T : class
{
    context.CheckNotNull(nameof(context));
    model.CheckNotNull(nameof(context));

    context.Entry(existing).CurrentValues.SetValues(model);
    await context.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
}

Answer 13

这是最简单的解决方案

JobDb dbContext = new JobDb（）; dbContext.Update（job）;

        var entry = dbContext.EventLogs.FirstOrDefault(x => x.JobId == job.JobId && x.EventId == eventId);

        if (entry != null)
        {
            dbContext.Entry(entry).CurrentValues.SetValues(new JobLog() { JobId = job.JobId, EventId = eventId, Status = status, DateStamp = DateTime.Now, LogId = entry.LogId });
        }
        else
        {
            if (job.JobLogs is null)
                job.JobLogs = new List<JobLog>();

            var JobLog = new JobLog() { JobId = job.JobId, EventId = eventId, Status = status, DateStamp = DateTime.Now };
            job.JobLogs.Add(JobLog);
        }
        dbContext.SaveChanges();

Answer 14

请参阅我的一个项目中的以下代码片段，其中我实现了同样的事情。如果有新条目，它将保存数据，如果存在则更新，如果发布 json 中的记录不可用则删除。帮助您理解架构的 Json 数据：

{
    "groupId": 1,
    "groupName": "Group 1",
    "sortOrder": 1,
    "filterNames": [
        {
            "filterId": 1,
            "filterName1": "Name11111",
            "sortOrder": 10,
            "groupId": 1           
        }  ,
        {
            "filterId": 1006,
            "filterName1": "Name Changed 1",
            "sortOrder": 10,
            "groupId": 1           
        }  ,
        {
            "filterId": 1007,
            "filterName1": "New Filter 1",
            "sortOrder": 10,
            "groupId": 1           
        } ,
        {
            "filterId": 2,
            "filterName1": "Name 2 Changed",
            "sortOrder": 10,
            "groupId": 1           
        }                 
    ]
}


public async Task<int> UpdateFilter(FilterGroup filterGroup)
        {                        
            var Ids = from f in filterGroup.FilterNames select f.FilterId;
            var toBeDeleted = dbContext.FilterNames.Where(x => x.GroupId == filterGroup.GroupId
            && !Ids.Contains(x.FilterId)).ToList();
            foreach(var item in toBeDeleted)
            {
                dbContext.FilterNames.Remove(item);
            }
            await dbContext.SaveChangesAsync();

            dbContext.FilterGroups.Attach(filterGroup);
            dbContext.Entry(filterGroup).State = EntityState.Modified;
            for(int i=0;i<filterGroup.FilterNames.Count();i++)            
            {
                if (filterGroup.FilterNames.ElementAt(i).FilterId != 0)
                {
                    dbContext.Entry(filterGroup.FilterNames.ElementAt(i)).State = EntityState.Modified;
                }
            }            
            return await dbContext.SaveChangesAsync();
        }

如何在EF中更新父实体时添加/更新子实体

14 个答案:

注意：