实体框架6更新图表

Question

保存不知道状态的对象图的正确方法是什么？按状态我的意思是它们是新的还是现有的数据库条目正在更新.

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,我碰巧使用实体框架.所以我将这些模型转换为DAL内部的POCO实体.

似乎除非我的模型具有指示它们是新的还是更新的状态,否则我还有很多工作要做"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汽车,然后为每个汽车检查任何新的或更新的维护记录.

有更快/更简单的方法吗？我可以跟踪模型状态,我想这会对此有所帮助,但这意味着要更改数​​据层之外的代码,我宁愿避免.我只是希望有一种使用模式,我可以关注这样的更新.

Answer 1

我前一段时间遇到了这个问题,并且一直关注EF Codeplex网站上的这个帖子.https://entityframework.codeplex.com/workitem/864

好像它正在考虑下一个版本,我假设EF 7,这显然是一个相当大的EF内部改革.这可能值得一试...... http://www.nuget.org/packages/RefactorThis.GraphDiff/

回到我的工作时,我在SO上发现了另一个EF帖子,有人举了一个如何手动执行此操作的示例.当时我决定手动完成,不知道为什么,GraphDiff看起来很酷.这是我所做的一个例子.

  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();
    }