这两个实体是一对多关系(由代码第一个fluent 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，我有创建父实体(工作正常)和更新父实体(有一些问题)的操作。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:
获取一个被跟踪的父实体，命名为按模型存在的。Id，并将模型中的值逐个分配给实体。这听起来很愚蠢。在模型中。我不知道哪个子是新的，哪个子是修改的(甚至是删除的)。
通过模型创建一个新的父实体，并将其附加到DbContext并保存。但是DbContext如何知道子节点的状态(新增/删除/修改)呢?
实现这个功能的正确方法是什么?
这不是最优雅的方法，但很有效。干杯!
var entity = await context.Entities.FindAsync(id);
var newEntity = new AmazingEntity() {
p1 = child1
p2 = child2
p3 = child3.child4 //... nested collections
};
if (entity != null)
{
db.Entities.Remove(entity);
}
db.Entities.Add(newEntity);
await db.SaveChangesAsync();
记住去掉PK。
var child4 = Tools.CloneJson(deepNestedElement);
child4.id = 0;
child3.Add(child4);
public static class Tools
{
public static JsonSerializerSettings jsonSettings = new JsonSerializerSettings {
ObjectCreationHandling = ObjectCreationHandling.Replace,
ReferenceLoopHandling = ReferenceLoopHandling.Ignore
};
public static string JSerialize<T>(T source) {
return JsonConvert.SerializeObject(source, Formatting.Indented, jsonSettings);
}
public static T JDeserialize<T>(string source) {
return JsonConvert.DeserializeObject<T>(source, jsonSettings);
}
public static T CloneJson<T>(this T source)
{
return CloneJson<T, T>(source);
}
public static TOut CloneJson<TIn, TOut>(TIn source)
{
if (Object.ReferenceEquals(source, null))
return default(TOut);
return JDeserialize<TOut>(JSerialize(source));
}
}
这是我的代码，工作得很好。
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;
}
这不是最优雅的方法，但很有效。干杯!
var entity = await context.Entities.FindAsync(id);
var newEntity = new AmazingEntity() {
p1 = child1
p2 = child2
p3 = child3.child4 //... nested collections
};
if (entity != null)
{
db.Entities.Remove(entity);
}
db.Entities.Add(newEntity);
await db.SaveChangesAsync();
记住去掉PK。
var child4 = Tools.CloneJson(deepNestedElement);
child4.id = 0;
child3.Add(child4);
public static class Tools
{
public static JsonSerializerSettings jsonSettings = new JsonSerializerSettings {
ObjectCreationHandling = ObjectCreationHandling.Replace,
ReferenceLoopHandling = ReferenceLoopHandling.Ignore
};
public static string JSerialize<T>(T source) {
return JsonConvert.SerializeObject(source, Formatting.Indented, jsonSettings);
}
public static T JDeserialize<T>(string source) {
return JsonConvert.DeserializeObject<T>(source, jsonSettings);
}
public static T CloneJson<T>(this T source)
{
return CloneJson<T, T>(source);
}
public static TOut CloneJson<TIn, TOut>(TIn source)
{
if (Object.ReferenceEquals(source, null))
return default(TOut);
return JDeserialize<TOut>(JSerialize(source));
}
}
VB。NET开发人员使用这个通用子标记子状态，易于使用
注:
PromatCon:实体对象
amList:要添加或修改的子列表
rList:要删除的子列表
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
PromatCon.SaveChanges()
如果你正在使用EntityFrameworkCore，你可以在你的控制器post动作中做以下事情(Attach方法递归地附加导航属性，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();
假设每个被更新的实体都设置了所有属性，并在来自客户端的post数据中提供。不会为实体的部分更新工作)。
您还需要确保为该操作使用了一个新的/专用的实体框架数据库上下文。
