I am attempting to make a generic table viewer/editor for an MVC 6 application.
I currently use
Context.GetEntityTypes();
To return me a list of tables.
Now I need to fetch the data for a specific type. My current implementation is:
// On my context
public IQueryable<dynamic> GetDbSetByType(string fullname)
{
Type targetType = Type.GetType(fullname);
var model = GetType()
.GetRuntimeProperties()
.Where(o =>
o.PropertyType.IsGenericType &&
o.PropertyType.GetGenericTypeDefinition() == typeof(DbSet<>) &&
o.PropertyType.GenericTypeArguments.Contains(targetType))
.FirstOrDefault();
if (null != model)
{
return (IQueryable<dynamic>)model.GetValue(this);
}
return null;
}
With this code in my controller
[HttpGet("{requestedContext}/{requestedTable}/data")]
public IActionResult GetTableData(string requestedContext, string requestedTable)
{
var data = Request.Query;
var context = GetContext(requestedContext);
if (context == null)
{
return new ErrorObjectResult("Invalid context specified");
}
var entity = context.GetEntity(requestedTable);
if (entity == null)
{
return new ErrorObjectResult("Invalid table specified");
}
var set = context.GetDbSetByType(entity.ClrType.AssemblyQualifiedName);
if (set == null)
{
return new ErrorObjectResult("Invalid table specified - DbSet could not be found");
}
var start = Convert.ToInt32(data["start"].ToString());
var count = Convert.ToInt32(data["length"].ToString());
var search = data["search[value]"];
return new ObjectResult(set.Skip(start).Take(count));
}
As it is, this will return the data of length count
and from position start
. However I cannot perform queries on the specific properties of the IQueryable<dynamic>
.
The problem is:
object set
back to a DbSet<T>
so I can perform my queries? If I set a breakpoint and inspect I can see all my data just sitting there.NOTE: This is EF7
ADDITIONAL INFO:
requestedTable
is the fully qualified type EG: <mysystem>.Models.Shared.Users
EDIT (2016/5/5)
I ended up just doing it all in plain SQL - if anyone does manage to get this working please let me know!
This would be simpler by using a generic method and using DbContext.Set<TEntity>()
. You can create a generic method at runtime like this:
public IActionResult GetTableData(string requestedContext, string requestedTable)
{
var context = GetContext(requestedContext);
if (context == null)
{
return new ErrorObjectResult("Invalid context specified");
}
var entity = context.GetEntity(requestedTable);
if (entity == null)
{
return new ErrorObjectResult("Invalid table specified");
}
var boundMethod = s_getTableDataMethodInfo.MakeGenericMethod(entity.ClrType);
return boundMethod.Invoke(this, new object[] { context }) as IActionResult;
}
private static readonly MethodInfo s_getTableDataMethodInfo
= typeof(MyController).GetTypeInfo().GetDeclaredMethod("GetTableDataForEntity");
private IActionResult GetTableDataForEntity<TEntity>(DbContext context)
where TEntity : class
{
var data = Request.Query;
var start = Convert.ToInt32(data["start"].ToString());
var count = Convert.ToInt32(data["length"].ToString());
var search = data["search[value]"];
return new ObjectResult(context.Set<TEntity>().Skip(start).Take(count));
}