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Asp.NET Web api logging request and response

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Last Modified: 2016-08-11
Hi All

I want to log both JSON request and response made to my web api. Can you show me the standard way of implementing this

Thanks
Adib
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Commented:
Hi,

I have created such a solution which logs the messages in a table in the db. Of course you may use whatever logging solution you like.

I am using Ninject for Dependency Injection. In my case DbContext is my DB repository.
For this you need to create a class that will derive from DelegatingHandler. You will need to override SendAsync.

public class LoggingHandler: DelegatingHandler
{
    public DbContext _context {get;set;}
    protected override System.Threading.Tasks.Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
    {
        //Get the _context
        _context = (DbContext)request.GetDependencyScope().GetService(typeof(DbContext));

        //Declare the new Entity
        var logEntity = new Log();
        
        //Read the request body
        var requestMessageBytes = await request.Content.ReadAsByteArrayAsync();

        //Decode the message bytes to string and log them
        logEntity.RequestMessage = Encoding.UTF8.GetString(requestMessageBytes);

        //Log the request Headers
        var requestHeaders = request.Headers.Where(x => x.Value != null && x.Value.Count() > 0);

        var requestHeadersString = String.Empty;
        foreach(var header in request.Headers)
        {
            requestHeadersString += String.Format("{0}: {1}{2}", header.Key, String.Join(", ", header.Value), Environment.NewLine);
        }
        logEntity.RequestHeaders = requestHeadersString;

        //Release the request to the condroller and read the response
        var response = await base.SendAsync(request, cancellationToken);

        //Log the response status
        logEntity.ResponseHTTPStatusCode = response.StatusCode

        //Log the response body
        byte[] responseMessageBytes;

        if(response.Content != null)
        {
            responseMessage = await response.Content.ReadAsByteArrayAsync();
        }

        logEntity.ResponseBody = Encoding.UTF8.GetString(responseMessage);


       //Log the Response Headers
        var responseHeaders = response.Headers

        var responseHeadersString = String.Empty
        foreach(var header in response.Headers)
        {
            responseHeadersString += String.Format("{0}: {1}{2}", header.Key, String.Join(", ", header.Value), Environment.NewLine);
        }

        logEntity.ResponseHeaders = requestHeadersString;


       //Save the entry
        _context.Entities.Log.Add(logEntity);
        _context.SaveChanges();

    }

}

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Now you need to register this so it takes effect. What i do for this is put the following in Global.asax Application_Start :

        GlobalConfiguration.Configuration.MessageHandlers.Add(New LoggingHandler())

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Please make note that in my case i was using VB.Net, so i had to transform the code to C# for you. This means that i have not really tested this exact implementation but i guess it will. Let me know how it goes.

Giannis

Author

Commented:
Thanks . This would capture incoming Requests and outgoing Response from Web api?
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Commented:
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Author

Commented:
{"RequestMessage":"{\r\n  \"BID\" : \"1\",\r\n  \"EID\": \"2\",\r\n  \"TD\": \"3\",\r\n  \"SID\": \"4\",\r\n  \"ID\": \"5\",\r\n  \"Key\": \"93b\"\r\n}","RequestHeaders...................................

I am able to log. But I am getting  \r\n   or \  in the    logged request and response. Can we get rid of it.

Author

Commented:
Can we disable the web api handler or set it in Web.config. I don't want to trace in production.
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Commented:
Hi,

If you want to set it in the web.config then you could do it like this:

In web.config:

 <appSettings>
...
    <add key="EnableLogging" value="true" />
...
 </appSettings>

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In Global.asax Application_Start :

if(ConfigurationManager.AppSettings["EnableLogging"] == "true")
{
    GlobalConfiguration.Configuration.MessageHandlers.Add(New LoggingHandler())
}

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Another way without the web.config change would be:


In Global.asax Application_Start :

#if DEBUG
    GlobalConfiguration.Configuration.MessageHandlers.Add(New LoggingHandler())
#endif

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I prefer the first way though ;-).

By the way, i missed your other question on how to get rid of the \r\n s etc. Do you still have a problem with that?

Giannis

Author

Commented:
Thanks..Yes I still have that issue.
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Commented:
Well you may try this:

var escapedString = "{\r\n  \"SomeResponse\":\r\n  {\r\n    \"FIrstAttribute\":8,\r\n    \"SecondAttribute\":\"On\"\r\n  }\r\n}";
var result = System.Text.RegularExpressions.Regex.Unescape(escapedString);

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Giannis

Author

Commented:
Thanks

Author

Commented:
Thanks

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