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I have two main entities in my model. Report (also Report Table) and ReportFolder(also Table)

 [DataContract(IsReference = true)]
    public partial class Report
    {
        public Report()
        {
            this.DataSources = new List<DataSource>();
            CreationDate = DateTime.Now;

        }
        [DataMember]
        public long Id { get; set; }
        [DataMember]
        public long ReportFolderId { get; set; }
        [DataMember]
        public virtual ReportFolder ReportFolder { get; set; }
        [DataMember]
        public string Name { get; set; }
        [DataMember]
        public string ReportContent { get; set; }
......

    }
[DataContract(IsReference = true)]
public partial class ReportFolder
{
    public ReportFolder()
    {
        this.Reports = new List<Report>();
        this.Folders = new List<ReportFolder>();
        CreationDate = DateTime.Now;
    }

    [DataMember]
    public long Id { get; set; }
    [DataMember]
    public string Name { get; set; }
    [DataMember]
    public string Description { get; set; }
    [DataMember]
    public long? ParentId { get; set; }
    [DataMember]
    public virtual ICollection<Report> Reports { get; set; }
    [DataMember]
    public virtual ICollection<ReportFolder> Folders { get; set; }
.....
}

So the problem is , I am using my report in two scenarios, in one I need to load all the ReportFolders with Reports in this scenario I do not want load ReportContent(it is a heavy filed). In the other scenario I want to load and save a Report with the all fields. Based on my search entityframework does not support partially loading fields.

Then I decided to inherit form Report and make another class called ReportWithContent and in this class map ReportContent field (also remove this filed form Report class) and use this two class in different scenarios (sending one form client to server and respond the other to the client to prevent to much data transfer) but I was not successful it needed a discriminator which I do not have(EF exception). I am thinking of having Report without mapping ReportContent in this case whatever action I should use ReportContent I will have to use plain Sql which I do not know is a good practice or not.

Mojtaba
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1 Answers1

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It isn't possible to lazy load a primitive property with the EF. All primitive properties are loaded automatically.

A solution is to wrap content of the report in another entity and use this entity instead of the string property in the Report class.

public class ReportContent {
    public int ID { get; set; }
    public string Text { get; set; }
}

public class Report {
    ...
    public virtual ReportContent Content { get; set; }
    ...
}
Lukas Kabrt
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  • thanks I write my entities POCO myself not any code migration (tables already are in the DB reverse codefirst ) I got the error Maybe I should give up using inheritance and go for table split (your solution ) – Mojtaba Oct 17 '13 at 14:18
  • I had thought one more time over the idea of inheritance I realized that it can't work. It isn't possible to map one row from the table to the two different entities. – Lukas Kabrt Oct 17 '13 at 17:51
  • I wanted to have Report and ReportWithContent which is inherited from Report so they are is inheritance between to types. So it means it is not possible to map parent and child to one table? – Mojtaba Oct 18 '13 at 11:19
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    It is possible to map a parent and a child to the one table - it's called Table per Hierarchy (TPH). But it isn't possible to have a row in such table and one time load it as `Report` and the other time as `ReportWithContent`. To make it work you need to have two copies of the report in the database - one saved as `Report` the other one as `ReportWithContent` and it's very bad idea. – Lukas Kabrt Oct 18 '13 at 11:29
  • I'd recommend using EF's table splitting feature. – SepehrM May 16 '16 at 22:08