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I am using ASP.NET WEB API Odata libraries. If I use substringof in my call and the value is null it fails.

The URI I am passing is: ... odata/MyEntity()?$filter=substringof(null,Name) ...

And the result is: 

<?xml version="1.0" encoding="utf-8"?>
<m:error xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
  <m:code />
  <m:message xml:lang="en-US">The query specified in the URI is not valid.</m:message>
  <m:innererror>
    <m:message>The 'substringof' function cannot be applied to an enumeration-typed argument.</m:message>
    <m:type>Microsoft.Data.OData.ODataException</m:type>
    <m:stacktrace>   at System.Web.Http.OData.Query.Expressions.FilterBinder.ValidateAllStringArguments(String functionName, Expression[] arguments)&#xD;
   at System.Web.Http.OData.Query.Expressions.FilterBinder.BindSubstringOf(SingleValueFunctionCallNode node)&#xD;
   at System.Web.Http.OData.Query.Expressions.FilterBinder.BindSingleValueFunctionCallNode(SingleValueFunctionCallNode node)&#xD;
   at System.Web.Http.OData.Query.Expressions.FilterBinder.Bind(QueryNode node)&#xD;
   at System.Web.Http.OData.Query.Expressions.FilterBinder.BindFilterClause(FilterClause filterClause, Type filterType)&#xD;
   at System.Web.Http.OData.Query.Expressions.FilterBinder.Bind(FilterClause filterClause, Type filterType, IEdmModel model, IAssembliesResolver assembliesResolver, ODataQuerySettings querySettings)&#xD;
   at System.Web.Http.OData.Query.FilterQueryOption.ApplyTo(IQueryable query, ODataQuerySettings querySettings, IAssembliesResolver assembliesResolver)&#xD;
   at System.Web.Http.OData.Query.ODataQueryOptions.ApplyTo(IQueryable query, ODataQuerySettings querySettings)&#xD;
   at System.Web.Http.QueryableAttribute.ApplyQuery(IQueryable queryable, ODataQueryOptions queryOptions)&#xD;
   at System.Web.Http.QueryableAttribute.ExecuteQuery(IEnumerable query, HttpRequestMessage request, HttpActionDescriptor actionDescriptor)&#xD;
   at System.Web.Http.QueryableAttribute.OnActionExecuted(HttpActionExecutedContext actionExecutedContext)</m:stacktrace>
  </m:innererror>
</m:error>

So it seems it is an issue in the WEB API Odata libraries. Is there any way to prevent it?

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1 Answer

up vote 1 down vote accepted

That is supposed to fail - null will never be a substring of a string. $filter=substringof(null, Name) is equivalent in code to something like Where(i => i.Name.Contains(null)), which throws an ArgumentNullException.

If you want to check whether the value is null, you can use something like $filter=Name eq null, or to check whether it's null or a substring of the name, you can do $filter=(Name eq null) or (substringof('theValue', Name)).

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