XML deserialization failing from one webAPI and not another-CodePudding

My environment: Visual Studio 2010

I have 2 C# webAPI projects that return data to a VB client project.

API project #1: OrchardsAPI - returns lots of data perfectly.

API project #2: aspnetAPI - accesses the Microsoft aspnetdb database on my SQL server. Throws an exception when deserialized on the Client.

When I interrogate the API projects directly from my browser, the following is the first the first line each response. API#1 returns a list of cultivars used in my orchards. Note the xmlns values.

API #1:

<ArrayOfCultivarEntity xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">

API #2:

<ArrayOfaspnet_RoleEntity xmlns:i="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.datacontract.org/2004/07/aspnetEntities">

When accessed directly from a browser, a valid xml file is displayed with records from each API. However, when I get request the data from my Client, I get an exception stating that:

InnerException  {"<ArrayOfaspnet_RoleEntity xmlns='http://schemas.datacontract.org/2004/07/aspnetEntities'> was not expected."}

The relevant code in my client is:

   Public Function GetAllRoles() As List(Of aspnetEntities.aspnet_RoleEntity)
        Dim _entities As New List(Of aspnet_RoleEntity)
        Try
            url = "role/byAppName/OrchardAutomation"
            responseMessage = client.GetAsync(url).Result
            If responseMessage.IsSuccessStatusCode = True Then
                _entities = New Xml.Serialization.XmlSerializer(_entities.GetType).Deserialize(responseMessage.Content.ReadAsStreamAsync.Result)
                Return _entities
            Else
                ProcessClientError(responseMessage.Content.ReadAsStringAsync.Result)
                Return Nothing
            End If
        Catch ex As Exception
            ProcessClientException(ex)
            Return Nothing
        End Try
    End Function

I have searched for all instances of "xmlns" in both API projects and they are all identical. There must be something I'm missing. Any hints greatly appreciated.

CodePudding user response：

Solved thanks to the following link: [https://docs.microsoft.com/de-de/aspnet/web-api/overview/formats-and-model-binding/json-and-xml-serialization#xml_media_type_formatter]

Turns out my API #1 had the following code in the global.asax file:

GlobalConfiguration.Configuration.Formatters.XmlFormatter.MediaTypeMappings.Add(new QueryStringMapping("type", "xml", new System.Net.Http.Headers.MediaTypeHeaderValue("application/xml")));
GlobalConfiguration.Configuration.Formatters.Remove(GlobalConfiguration.Configuration.Formatters.JsonFormatter);
GlobalConfiguration.Configuration.Formatters.XmlFormatter.UseXmlSerializer = true;

The aforementioned link noted that the datacontract serializer was the default and one had to add the code to switch to the xml formatter:

var xml = GlobalConfiguration.Configuration.Formatters.XmlFormatter;
xml.UseXmlSerializer = true;

Which I put in the initialization section of my controller. That solved the problem. I then looked at the global.asax in API#1 and found the 3 lines in the app_start method. I inserted them into the app_start of API#2, removed the "var xml" lines from the initialization of the individual controller and the project continued to work perfectly.

Hope this helps someone else!