Eager loading Not retrieving data for child class MVC - asp.net-mvc

Question

I have the following classes defined in my project
public class PolicyDocs
{
[Key]
[Required]
[MaxLength(20)]
public string PolicyDocID { get; set; }
[DisplayName("Date Revised")]
public DateTime DateRevised { get; set; }
[MaxLength(500)]
[DisplayName("Document Name")]
public string DocumentName { get; set; }
[MaxLength(10)]
[DisplayName("Version")]
public string VersionNo { get; set; }
[MaxLength(255)]
[DisplayName("Location")]
public string DocumentPath { get; set; }
public string CategoryID { get; set; }
public ICollection<PolicyDocumentsCatagory> PolicyDocumentsCatagory { get; set; }
}
and
public class PolicyDocumentsCatagory
{
[Key]
[MaxLength(20)]
//[Required]
public string CategoryID { get; set; }
[MaxLength(20)]
[Required]
[DisplayName("Description")]
public string CategoryDesc { get; set; }
[DisplayName("Active")]
public Boolean IsActive{ get; set; }
}
Data is properly loaded in to the table .
Example:
PolicyDocs:
1 ,"12-Jan-2017", "Document 1","version 1",100
PolicyDocumentsCategory:
100, "Information Technology", "true".
I am using the following query in my Controller Class
_context = new ApplicationDbContext();
//PolicyDocs _Policy = new PolicyDocs();
var _LPolicies = _context.PolicyDocs.Include(i=> i.PolicyDocumentsCatagory).ToList();
return PartialView("_GetAllPolicies", _LPolicies);
While running the query I am unable to see any data loaded for PolicyDocumentsCategory in "_LPolicies" object. The query is loading data in table "PolicyDocs".
Nor I am able to reference the PolicyDocumentsCategory in VIEW. I can not see the properties of "PolicyDocumentsCatagory" in the view
#model IEnumerable< MyRTOCloud.DBModels.PolicyDocs>
<div class="row">
<div>
<table id="Categories" class="table table-hover">
<thead>
<th>Category</th>
<th>Document Name</th>
<th>Release Date</th>
<th>Version</th>
</thead>
#foreach (var lp in Model)
{
<tr>
<td>#lp.PolicyDocumentsCatagory.____</td> // I can not see any peroprty of "PolicyDocumentsCatagory"
<td>#lp.DocumentName </td>
<td>#lp.DateRevised </td>
<td>#lp.VersionNo </td>
</tr>
}
</table>
</div>
</div>
Thanks,

Answer 1

PolicyDocumentsCatagory is a collection and you have to iterate it in itself or in your case you can combine with a separator as a string.
So, try something like that;
<td>#string.Join(",", lp.PolicyDocumentsCatagory.Select(x => x.CategoryID))</td>

Answer 2

Your PolicyDocs class is referencing a single CategoryID leading me to assume this is a one-to-many relationship (PolicyDocs being the many, PolicyDocumentsCatagory being the one). If that is the case, you will want to change your PolicyDocumentsCatagory property in PolicyDocs to public virtual PolicyDocumentsCatagory PolicyDocumentsCatagory { get; set; }. Note the virtual part. This is what allows EF to populate the relationship property automatically.

Answer 3

public class PolicyDocs
{
[Key]
[Required]
[MaxLength(20)]
public string PolicyDocID { get; set; }
[DisplayName("Date Revised")]
public DateTime DateRevised { get; set; }
[MaxLength(500)]
[DisplayName("Document Name")]
public string DocumentName { get; set; }
[MaxLength(10)]
[DisplayName("Version")]
public string VersionNo { get; set; }
[MaxLength(255)]
[DisplayName("Location")]
public string DocumentPath { get; set; }
public ICollection<PolicyDocumentsCatagory> PolicyDocumentsCatagory { get; set; }
}
public class PolicyDocumentsCatagory
{
[Key]
[MaxLength(20)]
public string CategoryID { get; set; }
[Required]
[MaxLength(20)]
public string PolicyDocID { get; set; }
[ForeignKey]
public PolicyDocs PolicyDocs { get; set; }
[MaxLength(20)]
[Required]
[DisplayName("Description")]
public string CategoryDesc { get; set; }
[DisplayName("Active")]
public Boolean IsActive{ get; set; }
}
Your models are not valid. You need to have a foreign key in your PolicyDocumentsCatagory that referencing to PolicyDocs and there is no need for CategoryID in PolicyDocs.
One PolicyDocs has many PolicyDocumentsCatagory, while one PolicyDocumentsCatagory is referenced to only one PolicyDocs. Standard one to many relationship type.