private Expression Process(Expression visited, Expression processed)
{
if (this.processor == null)
{
this.processor = this.context.QueryContext.GetApiService <IQueryExpressionProcessor>();
}
if (this.processor != null)
{
var filtered = processor.Process(this.context);
var callback = this.context.AfterNestedVisitCallback;
this.context.AfterNestedVisitCallback = null;
if (filtered != null && filtered != visited)
{
if (!visited.Type.IsAssignableFrom(filtered.Type))
{
// In order to filter on the navigation properties,
// the type is changed from ICollection<> to IQueryable<>
var collectionType = visited.Type.FindGenericType(typeof(ICollection <>));
var queryableType = filtered.Type.FindGenericType(typeof(IQueryable <>));
if (collectionType == null || queryableType == null)
{
throw new InvalidOperationException(
Resources.ProcessorCannotChangeExpressionType);
}
var queryableElementType = queryableType.GenericTypeArguments[0];
var collectionElementType = collectionType.GenericTypeArguments[0];
if (collectionElementType != queryableElementType &&
!queryableElementType.IsAssignableFrom(collectionElementType))
{
throw new InvalidOperationException(
Resources.ProcessorCannotChangeExpressionType);
}
}
this.processedExpressions.Add(visited, processed);
this.context.PushVisitedNode(null);
try
{
processed = this.Visit(filtered);
}
finally
{
this.context.PopVisitedNode();
this.processedExpressions.Remove(visited);
}
if (callback != null)
{
callback();
}
}
}
return(processed);
}
/// <summary>
/// Initializes a new instance of the DefaultQueryHandler class.
/// </summary>
/// <param name="sourcer">The query expression sourcer to use.</param>
/// <param name="authorizer">The query expression authorizer to use.</param>
/// <param name="expander">The query expression expander to use.</param>
/// <param name="processor">The query expression processor to use.</param>
public DefaultQueryHandler(IQueryExpressionSourcer sourcer,
IQueryExpressionAuthorizer authorizer = null,
IQueryExpressionExpander expander = null,
IQueryExpressionProcessor processor = null)
{
Ensure.NotNull(sourcer, nameof(sourcer));
this.authorizer = authorizer;
this.expander = expander;
this.processor = processor;
this.sourcer = sourcer;
}
public QueryExpressionVisitor(QueryContext context,
IQueryExpressionSourcer sourcer,
IQueryExpressionAuthorizer authorizer = null,
IQueryExpressionExpander expander = null,
IQueryExpressionProcessor processor = null)
{
Ensure.NotNull(sourcer, nameof(sourcer));
this.context = new QueryExpressionContext(context);
this.authorizer = authorizer;
this.expander = expander;
this.processor = processor;
this.sourcer = sourcer;
processedExpressions = new Dictionary <Expression, Expression>();
}
private Expression Process(Expression visited, Expression processed)
{
if (this.processor == null)
{
this.processor = this.context.QueryContext.GetApiService<IQueryExpressionProcessor>();
}
if (this.processor != null)
{
var filtered = processor.Process(this.context);
var callback = this.context.AfterNestedVisitCallback;
this.context.AfterNestedVisitCallback = null;
if (filtered != null && filtered != visited)
{
if (!visited.Type.IsAssignableFrom(filtered.Type))
{
// In order to filter on the navigation properties,
// the type is changed from ICollection<> to IQueryable<>
var collectionType = visited.Type.FindGenericType(typeof(ICollection<>));
var queryableType = filtered.Type.FindGenericType(typeof(IQueryable<>));
if (collectionType == null || queryableType == null)
{
throw new InvalidOperationException(
Resources.ProcessorCannotChangeExpressionType);
}
var queryableElementType = queryableType.GenericTypeArguments[0];
var collectionElementType = collectionType.GenericTypeArguments[0];
if (collectionElementType != queryableElementType
&& !queryableElementType.IsAssignableFrom(collectionElementType))
{
throw new InvalidOperationException(
Resources.ProcessorCannotChangeExpressionType);
}
}
this.processedExpressions.Add(visited, processed);
this.context.PushVisitedNode(null);
try
{
processed = this.Visit(filtered);
}
finally
{
this.context.PopVisitedNode();
this.processedExpressions.Remove(visited);
}
if (callback != null)
{
callback();
}
}
}
return processed;
}