/// <summary>
/// Extracts the filter definition once a leaf is found.
/// </summary>
/// <param name="info">QueryInformation being filled.</param>
/// <param name="binaryNode">BinaryOperatorNode the leaf belongs to.</param>
/// <param name="constantNode">ConstantNode with the parameter definition.</param>
private void ProcessLeafNode(QueryInformation info, BinaryOperatorNode binaryNode, ConstantNode constantNode)
{
try
{
// Necesary variables
SingleValuePropertyAccessNode propertyAccessNode = binaryNode.Left as SingleValuePropertyAccessNode;
SingleValueFunctionCallNode functioncall = binaryNode.Left as SingleValueFunctionCallNode;
// The filter definition that is going to be added.
FilterParameterDefinition filterdefinition = new FilterParameterDefinition();
// Populating common values.
filterdefinition.FilteringOperator = (FilteringOperator)binaryNode.OperatorKind;
filterdefinition.StringValue = constantNode.Value.ToString();
if (functioncall != null)
{
// it contains a function call
propertyAccessNode = ParseFunctionCall(propertyAccessNode, functioncall, filterdefinition);
}
if (propertyAccessNode != null)
{
//it is a simple equals
ParsePropertyAccessNode(info, propertyAccessNode, filterdefinition);
}
}
catch (Exception ex)
{
LogException(ex);
}
}
/// <summary>
/// Parses an ODataQueryOptions objects exposing its features in a custom object.
/// </summary>
/// <param name="options">ODataQueryOptions given by the ASP.NET Web Odata API controller.</param>
/// <returns>A QueryInformation containing the parsing results.</returns>
/// <remarks>
/// We currently support only the Filter aspects of the ODataQueryOptions object.
/// </remarks>
public QueryInformation Parse(ODataQueryOptions options)
{
QueryInformation info = new QueryInformation();
ParseFilterData(options.Filter, info);
return(info);
}
/// <summary>
/// Performs a Binary search on the abstract syntax tree of the filter expression.
/// </summary>
/// <param name="node">The node that needs to be searched on.</param>
/// <param name="info">The QueryInformation where we are accumulating the filter definitions. </param>
private void BinarySearchForNodes(QueryNode node, QueryInformation info)
{
try
{
var binaryNode = node as BinaryOperatorNode;
if (binaryNode != null)
{
// We look for constant nodes that would mean a leaf have been reached.
ConstantNode constantNode = GetConstantNode(binaryNode);
if (constantNode != null)
{
ProcessLeafNode(info, binaryNode, constantNode);
}
else
{
BinarySearchForNodes(binaryNode.Left, info);
BinarySearchForNodes(binaryNode.Right, info);
}
}
else
{
var convertNode = node as ConvertNode;
if (convertNode != null)
{
BinarySearchForNodes(convertNode.Source, info);
}
else
{
LogWarning(string.Format("Node wasn't casted as binary node. Type is {0}", node.GetType().FullName));
}
}
}
catch (Exception ex)
{
LogException(ex);
}
}
/// <summary>
/// Parses the Filter portion of the ODataQueryOptions object and adds its details to the used QueryInformation.
/// </summary>
/// <param name="filter">FilterQueryOption object contained in the ODataQueryOptions from the OData controller.</param>
/// <param name="info">The QueryInformation object that is maintained to give back the results.</param>
public void ParseFilterData(FilterQueryOption filter, QueryInformation info)
{
try
{
// If the filter comes null, there is no work to be done by this method.
if (filter == null)
{
return;
}
// There is at least one parameter so we instantiate the collection in the info object.
info.FilterParameters = new ODataFilterParameterCollection();
// The abstract syntax tree of the expression is a binary tree, we perform it here from the root.
BinarySearchForNodes(filter.FilterClause.Expression, info);
return;
}
catch (Exception ex)
{
LogException(ex);
}
}
/// <summary>
/// Parses a Property access node.
/// </summary>
/// <param name="info">QueryInformation being filled.</param>
/// <param name="propertyAccessNode">Property access node to be parsed.</param>
/// <param name="filterdefinition">Filter definition being filled.</param>
private static void ParsePropertyAccessNode(QueryInformation info, SingleValuePropertyAccessNode propertyAccessNode, FilterParameterDefinition filterdefinition)
{
filterdefinition.FieldName = propertyAccessNode.Property.Name;
info.FilterParameters.Add(filterdefinition);
}