private async Task <List <TResult> > ToListAsync(IQueryable <TResult> query)
{
IQueryable <object> runtimeTypeSelectExpressionQuery = ToObjectQuery(query);
// Get result from database
List <object> listOfObjects = await runtimeTypeSelectExpressionQuery.ToListAsync();
MethodInfo castMethod = typeof(Queryable)
.GetMethod("Cast", BindingFlags.Public | BindingFlags.Static)
.MakeGenericMethod(_proxyType);
// Cast list<objects> to IQueryable<runtimeType>
IQueryable castedSource = castMethod.Invoke(
null,
new Object[] { listOfObjects.AsQueryable() }
) as IQueryable;
// Create instance of runtime type parameter
ParameterExpression runtimeParameter = Expression.Parameter(_proxyType, "p");
IDictionary <string, PropertyInfo> dynamicTypeFieldsDict =
_proxyProperties.ToDictionary(f => f.Name.ToLowerInvariant(), f => f);
// Generate bindings from runtime type to source type
IEnumerable <MemberBinding> bindingsToTargetType = _selectedProperties.Values
.Select(property => Expression.Bind(
property,
Expression.Property(
runtimeParameter,
dynamicTypeFieldsDict[property.Name.ToLowerInvariant()]
)
));
// Generate projection trom runtimeType to T and cast as IQueryable<object>
IQueryable <TResult> targetTypeSelectExpressionQuery
= ExpressionMapper.GenerateProjectedQuery <TResult>(
_proxyType,
typeof(TResult),
bindingsToTargetType,
castedSource,
runtimeParameter
);
// Return list of T
return(targetTypeSelectExpressionQuery.ToList());
}
private IQueryable <object> ToObjectQuery(IQueryable <TResult> query)
{
IEnumerable <string> selectedPropertyNames = (_fields ?? "").ToLowerInvariant().Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries).Select(p => p.Trim());
// Take properties from the mapped entitiy that match selected properties
_selectedProperties = GetSelectableProperties <TResult>(selectedPropertyNames);
selectedPropertyNames = _selectedProperties.Keys;
// Construct runtime type by given property configuration
_proxyType = ProxyGenerator.CreateClassProxy <TResult>().GetType();
// Create instance of source parameter
ParameterExpression sourceParameter = Expression.Parameter(typeof(TResult), "t");
// Take fields from generated runtime type
_proxyProperties = _proxyType.GetProperties();
// Elect selected fields if any.
if (selectedPropertyNames.Any())
{
_proxyProperties = _proxyProperties.Where(pi => selectedPropertyNames.Any(p => pi.Name.ToLowerInvariant() == p)).ToArray();
}
// Generate bindings from source type to runtime type
IEnumerable <MemberBinding> bindingsToRuntimeType = _proxyProperties
.Select(field => Expression.Bind(
field,
Expression.Property(
sourceParameter,
_selectedProperties[field.Name.ToLowerInvariant()]
)
));
// Generate projection trom T to runtimeType and cast as IQueryable<object>
IQueryable <object> runtimeTypeSelectExpressionQuery
= ExpressionMapper.GenerateProjectedQuery <object>(
typeof(TResult),
_proxyType,
bindingsToRuntimeType,
query,
sourceParameter
);
return(runtimeTypeSelectExpressionQuery);
}