Asp.Net Core MVC Custom OutputFormatter to send Word Document as a response

I tried to find a way to serve word document from a Memory Stream using byte array as we do in our Web API to send documents in the response. But Asp.Net Core WepAPI Response object has no supporting methods to support this feature. We need to save the file from memory to Disk and use that path to server the file.

Our requirement is to Open Word document template into memory and do some changes to the document on the fly based on the user request. We were able to achieve this using ASP.NET web API using the below code

  public HttpResponseMessage Get()  
     {  
       GenerateMyDocument gd = new GenerateMyDocument();  
       byte[] documentContent = gd.GetDocumentParameters(3, "ISQ839343", "Venkat", "sept 19 2019");  
       HttpResponseMessage response = new HttpResponseMessage(HttpStatusCode.OK);  
       response.Content = new ByteArrayContent(documentContent);  
       response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/msword");  
       response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("inline")  
       {  
         FileName = "some.docx"  
       };  
       return response;  
     }  

        

The default format used by ASP.NET Core MVC is JSON.To send other content types as a response, we need to implement our own OutputFormatter. To deliver word document as a response we followed below steps.

Create a new class WordOutputFormatter inheriting from OutputFormatter. The below two methods we need to override to return our word document as a content type.

public class WordOutputFormatter : OutputFormatter
    {
        public string ContentType { get; }

        public WordOutputFormatter()
        {
            ContentType = "application/ms-word";
            SupportedMediaTypes.Add(MediaTypeHeaderValue.Parse(ContentType));
        }

        //we need to check whether the context Object is what we need to format
        // We must override this method to keep the normal execution flow for other action methods
        public override bool CanWriteResult(OutputFormatterCanWriteContext context)
        {
            return context.Object is Jurer;
        }

        public async override Task WriteResponseBodyAsync(OutputFormatterWriteContext context)
        {
            IServiceProvider serviceProvider = context.HttpContext.RequestServices;
            var response = context.HttpContext.Response;

            var buffer = new StringBuilder();
            Jurer jurer = null;
            if (context.Object is Jurer)
            {
                jurer = context.Object as Jurer;
            }

            response.Headers.Add("Content-Disposition", "inline;filename=jurer.docx");
            response.ContentType = "application/ms-word";

            string documentFilePath = DocumentHelper.GetDocumentParameters(jurer.JurisdictionID,jurer.JurorID,jurer.JurorName,jurer.Eventdate);


            await response.SendFileAsync(documentFilePath);
        }




    }

    

Now In your Controller add the below Action method

     [HttpGet]  
     [DeleteFileAttribute]  
     public IActionResult Get(int juridictionid, string jurerid,string jurername, string date)  
     {  
       Jurer jurer = new Jurer()  
       {  
         JurisdictionID = juridictionid,  
         JurorID = jurerid,  
         JurorName = jurername,  
         Eventdate = date,  
       };  
       return Ok(jurer);  
     }  

       

We are using [DeleteFileAttribute] inherited from  ActionFilterAttribute to Delete the word document we recently created from Word template and saved to Disk

    public class DeleteFileAttribute : ActionFilterAttribute

    {

         

        public override void OnResultExecuted(ResultExecutedContext filterContext)

        {           

          //write your cleanup logic to delete temp files created in the previous step.

        }

    }

To invoke our custom WordOutputFormatter we need to alter ConfigureServices method from Startup.cs as shown below

        public void ConfigureServices(IServiceCollection services)
        {
            // Add framework services.
            services.AddMvc(options =>
            {
                options.RespectBrowserAcceptHeader = true; // false by default
                options.OutputFormatters.Insert(0,new WordOutputFormatter());
                options.FormatterMappings.SetMediaTypeMappingForFormat(
                  "docx", MediaTypeHeaderValue.Parse("application/ms-word"));
            });

          
        }