I'm currently messing about with generics and I'm trying to write a function that I can call to load everything from a database table simply by specifying the table name.
I'm most of the way there; my generic methods all seem to work, but I'm not quite sure how to cast my results into something usable.
This is the guts of the method so far:
private static List<EntityCodeBase> GetCodeLoadResults(CodeTables table)
{
List<EntityCodeBase> results = new List<EntityCodeBase>();
Assembly assm = Assembly.Load(new System.Reflection.AssemblyName("RR"));
Type tableType = assm.GetTypes().Where(u => u.Name.ToLower() == table.ToString().ToLower()).FirstOrDefault();
MethodInfo mi = typeof(SpecificEntity).GetMethod("LoadAll");
mi = mi.MakeGenericMethod(tableType);
mi.Invoke(null, null); //how can I cast the resulting object into a List<EntityCodeBase> ?
return results;
}
Assuming SpecificEntity.LoadAll
returns a list of some type derived from EntityCodeBase
, you can't cast directly to a List<EntityCodeBase>
but you can cast to IEnumerable<EntityCodeBase>
. Then you can create a new list:
var ecbList = (IEnumerable<EntityCodeBase>)mi.Invoke(null, null);
return list.ToList();
It might be cleaner however, if you can get the table name from the entity type, either directly by name, using attributes, or using a map. Then you can make GetCodeLoadResults
generic in the result type e.g.
private static List<T> GetCodeLoadResults() where T : EntityCodeBase
{
Assembly assm = Assembly.Load(new System.Reflection.AssemblyName("RR"));
Type tableType = //get table type from T
MethodInfo mi = typeof(SpecificEntity).GetMethod("LoadAll");
mi = mi.MakeGenericMethod(tableType);
return (List<T>)mi.Invoke(null, null);
}
If you're not using .Net 4, you can't cast a List<TDerived>
to an IEnumerable<TBase>
, so you'll have to cast to IEnumerable
first:
return ((System.Collections.IEnumerable)mi.Invoke(null, null))
.Cast<EntityCodeBase>()
.ToList();
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