private Expression AppendOnFilterExpression(QueryExpressionContext context, IEdmEntitySet entitySet, IEdmEntityType entityType)
{
var expectedMethodName = ConventionBasedMethodNameFactory.GetEntitySetMethodName(entitySet, RestierPipelineState.Submit, RestierEntitySetOperation.Filter);
var expectedMethod = targetApiType.GetQualifiedMethod(expectedMethodName);
if (expectedMethod == null || (!expectedMethod.IsFamily && !expectedMethod.IsFamilyOrAssembly))
{
if (expectedMethod != null)
{
Trace.WriteLine($"Restier Filter found '{expectedMethodName}' but it is unaccessible due to its protection level. Your method will not be called until you change it to 'protected internal'.");
}
else
{
var actualMethodName = expectedMethodName.Replace(entitySet.Name, entityType.Name);
var actualMethod = targetApiType.GetQualifiedMethod(actualMethodName);
if (actualMethod != null)
{
Trace.WriteLine($"BREAKING: Restier Filter expected'{expectedMethodName}' but found '{actualMethodName}'. Your method will not be called until you correct the method name.");
}
}
return(null);
}
var parameter = expectedMethod.GetParameters().SingleOrDefault();
if (parameter == null || parameter.ParameterType != expectedMethod.ReturnType)
{
return(null);
}
object apiBase = null;
if (!expectedMethod.IsStatic)
{
apiBase = context.QueryContext.Api;
if (apiBase == null || !targetApiType.IsInstanceOfType(apiBase))
{
return(null);
}
}
// The LINQ expression built below has three cases
// For navigation property, just add a where condition from OnFilter method
// For collection property, will be like "Param_0.Prop.AsQueryable().Where(...)"
// For collection property of derived type, will be like "Param_0.Prop.AsQueryable().Where(...).OfType()"
var returnType = context.VisitedNode.Type.FindGenericType(typeof(IQueryable <>));
var enumerableQueryParameter = (object)context.VisitedNode;
Type elementType = null;
if (returnType == null)
{
// This means append for properties model reference
var collectionType = context.VisitedNode.Type.FindGenericType(typeof(ICollection <>));
if (collectionType == null)
{
return(null);
}
elementType = collectionType.GetGenericArguments()[0];
returnType = typeof(IQueryable <>).MakeGenericType(elementType);
enumerableQueryParameter = Expression.Call(ExpressionHelperMethods.QueryableAsQueryableGeneric.MakeGenericMethod(elementType), context.VisitedNode);
}
else
{
elementType = returnType.GetGenericArguments()[0];
}
var queryType = typeof(EnumerableQuery <>).MakeGenericType(elementType);
var query = Activator.CreateInstance(queryType, enumerableQueryParameter);
if (!(expectedMethod.Invoke(apiBase, new object[] { query }) is IQueryable result))
{
return(null);
}
if (expectedMethod.ReturnType == returnType)
{
if (result != query)
{
return(result.Expression);
}
}
else
{
// This means calling onFilter against derived type and based type is returned
// Need to convert back to derived type with OfType
result = ExpressionHelpers.OfType(result, elementType);
return(result.Expression);
}
return(null);
}