Question

我正在使用 ASP.NET WEB API Odata 库。如果我在调用中使用substringof并且值为null则失败。

我传递的URI是：... odata/MyEntity()?$filter=substringof(null,Name) ...

结果是：

<?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>

因此，它似乎是WEB API Odata库中的一个问题。有什么办法可以阻止吗？

Answer 1

应该失败 - null永远不会是字符串的子串。 $filter=substringof(null, Name)在代码中等同于Where(i => i.Name.Contains(null))，它会抛出ArgumentNullException。

如果要检查值是否为null，可以使用$filter=Name eq null之类的内容，或者检查它是否为null或名称的子字符串，可以$filter=(Name eq null) or (substringof('theValue', Name))。

Asp.net web api odata substringof null问题

1 个答案: