How to parse OData $filter with regular expression in C#?

Question

Hi I\'m wondering what the best approach would be to parse an OData $filter string in C#, for example

/API/organisations?$filter=\"name eq \'Facebook\' or name eq \'

Answer 1

In .NET, there's a library available that will do this for you. Writing your own regex runs the risk of missing some edge case.

Using NuGet, bring in Microsoft.Data.OData. Then, you can do:

using Microsoft.Data.OData.Query;

var result = ODataUriParser.ParseFilter(
  "name eq 'Facebook' or name eq 'Twitter' and subscribers gt 30",
  model,
  type);

result here will be in the form of an AST representing the filter clause.

(To get the model and type inputs, you could parse your $metadata file using something like this:

using Microsoft.Data.Edm;
using Microsoft.Data.Edm.Csdl;

IEdmModel model = EdmxReader.Parse(new XmlTextReader(/*stream of your $metadata file*/));
IEdmEntityType type = model.FindType("organisation");

)