问题描述
保存不知道状态的对象图的正确方法是什么?状态是指它们是正在更新的新数据库条目还是现有数据库条目.
What is the correct way to save a graph of objects whose state you don't know? By state I mean whether they are new or existing database entries that are being updated.
例如，如果我有:
public class Person
{
public int Id { get; set; }
public int Name { get; set; }
public virtual ICollection<Automobile> Automobiles { get; set; }
}
public class Automobile
{
public int Id { get; set; }
public int Name { get; set; }
public short Seats { get; set; }
public virtual ICollection<MaintenanceRecord> MaintenanceRecords { get; set ;}
public virtual Person Person { get; set; }
}
public class MaintenanceRecord
{
public int Id { get; set; }
public int AutomobileId { get; set; }
public DateTime DatePerformed { get; set; }
public virtual Automobile Automobile{ get; set; }
}
我正在编辑模型，类似于上面的这些对象，然后将这些模型传递到数据层进行保存，对于这个实例，我碰巧使用了实体框架.所以我将这些模型转换为 DAL 内部的 POCO 实体.
I'm editing models, similar to these objects above, and then passing those models into the data layer to save, where for this instance I happen to be using entity framework. So I'm translating these models into POCO entities internal to the DAL.
看来，除非我的模型有一个状态表明它们是新的还是更新的，否则我还有很多工作要做来保存"更改.我必须首先选择 Person 实体，更新它，然后匹配任何现有的汽车并更新它们并添加任何新的，然后为每辆汽车检查任何新的或更新的维护记录.
It appears that unless my models have a state indicating whether they are new or updated, I have quite a bit of work to do to "Save" the changes. I have to first select the Person entity, update it, then match any existing Automobiles and update those and add any new, then for each automobile check for any new or updated maintenance records.
有没有更快/更简单的方法来做到这一点?有可能我可以跟踪模型状态，我想这会对此有所帮助，但这意味着我希望避免对数据层之外的代码进行更改.我只是希望有一种使用模式，我可以遵循这样的更新.
Is there a faster/easier way of doing this? It's possible I can keep track of the Model state, which I guess would be helpful with this, but it would mean changes to code outside of the data layer which i would prefer to avoid. I'm just hoping there is a pattern of usage out there that I can follow for updates like this.
推荐答案
我不久前遇到了这个问题，并且一直在关注 EF Codeplex 网站上的这个帖子.https://entityframework.codeplex.com/workitem/864
I ran into this issue a while back and have been following this thread on the EF Codeplex site. https://entityframework.codeplex.com/workitem/864
似乎正在考虑将其用于下一个版本，我假设是 EF 7，这显然是对 EF 的一次相当大的内部检修.这可能值得一试... http://www.nuget.org/packages/RefactorThis.GraphDiff/
Seems like it is being considered for the next release, I'm assuming EF 7, which apparently is a pretty large internal overhaul of EF. This may be worth checking out... http://www.nuget.org/packages/RefactorThis.GraphDiff/
当我在做这个的时候，我发现了另一个关于 SO 的 EF 帖子，有人有一个如何手动执行此操作的示例.当时我决定手动做，不知道为什么，GraphDiff 看起来很酷.这是我所做的一个例子.
Back when I was working on this I found another EF post on SO, and someone had an example of how to do this manually. At the time I decided to do it manually, not sure why, GraphDiff looks pretty cool. Here is an example of what I did.
public async Task<IHttpActionResult> PutAsync([FromBody] WellEntityModel model)
{
try
{
if (!ModelState.IsValid)
{
return BadRequest(ModelState);
}
var kne = TheContext.Companies.First();
var entity = TheModelFactory.Create(model);
entity.DateUpdated = DateTime.Now;
var currentWell = TheContext.Wells.Find(model.Id);
// Update scalar/complex properties of parent
TheContext.Entry(currentWell).CurrentValues.SetValues(entity);
//We don't pass back the company so need to attached the associated company... this is done after mapping the values to ensure its not null.
currentWell.Company = kne;
// Updated geometry - ARGHHH NOOOOOO check on this once in a while for a fix from EF-Team https://entityframework.codeplex.com/workitem/864
var geometryItemsInDb = currentWell.Geometries.ToList();
foreach (var geometryInDb in geometryItemsInDb)
{
// Is the geometry item still there?
var geometry = entity.Geometries.SingleOrDefault(i => i.Id == geometryInDb.Id);
if (geometry != null)
// Yes: Update scalar/complex properties of child
TheContext.Entry(geometryInDb).CurrentValues.SetValues(geometry);
else
// No: Delete it
TheContext.WellGeometryItems.Remove(geometryInDb);
}
foreach (var geometry in entity.Geometries)
{
// Is the child NOT in DB?
if (geometryItemsInDb.All(i => i.Id != geometry.Id))
// Yes: Add it as a new child
currentWell.Geometries.Add(geometry);
}
// Update Surveys
var surveyPointsInDb = currentWell.SurveyPoints.ToList();
foreach (var surveyInDb in surveyPointsInDb)
{
// Is the geometry item still there?
var survey = entity.SurveyPoints.SingleOrDefault(i => i.Id == surveyInDb.Id);
if (survey != null)
// Yes: Update scalar/complex properties of child
TheContext.Entry(surveyInDb).CurrentValues.SetValues(survey);
else
// No: Delete it
TheContext.WellSurveyPoints.Remove(surveyInDb);
}
foreach (var survey in entity.SurveyPoints)
{
// Is the child NOT in DB?
if (surveyPointsInDb.All(i => i.Id != survey.Id))
// Yes: Add it as a new child
currentWell.SurveyPoints.Add(survey);
}
// Update Temperatures - THIS IS A HUGE PAIN = HOPE EF is updated to handle updating disconnected graphs.
var temperaturesInDb = currentWell.Temperatures.ToList();
foreach (var tempInDb in temperaturesInDb)
{
// Is the geometry item still there?
var temperature = entity.Temperatures.SingleOrDefault(i => i.Id == tempInDb.Id);
if (temperature != null)
// Yes: Update scalar/complex properties of child
TheContext.Entry(tempInDb).CurrentValues.SetValues(temperature);
else
// No: Delete it
TheContext.WellTemperaturePoints.Remove(tempInDb);
}
foreach (var temps in entity.Temperatures)
{
// Is the child NOT in DB?
if (surveyPointsInDb.All(i => i.Id != temps.Id))
// Yes: Add it as a new child
currentWell.Temperatures.Add(temps);
}
await TheContext.SaveChangesAsync();
return Ok(model);
}
catch (Exception ex)
{
Trace.WriteLine(ex.Message);
}
return InternalServerError();
}
这篇关于Entity Framework 6 更新图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！