I have dotnet WebAPI and I'm trying to get a specific behaviour but am constantly getting 415 responses.
I have reproduced this by starting a new webapi project using dotnet new webapi on the command line. From there, I added two things: a new controller, and a model class. In my real project the model class is obviously a bit more complex, with inheritance and methods etc...
Here they are:
[HttpGet("/data")]
public async Task<IActionResult> GetModel(BodyParams input)
{
var response = new { Message = "Hello", value = input.valueOne };
return Ok(response);
}
public class BodyParams {
public bool valueOne { get; set; } = true;
}
My goal is that the user can call https://localhost:7222/data with no headers or body needed at all, and will get the response - BodyParams will be used with the default value of true. Currently, from postman, or from the browser, I get a 415 response.
I've worked through several suggestions on stack and git but nothing seems to be working for me. Specifically, I have tried:
Adding [FromBody(EmptyBodyBehavior = EmptyBodyBehavior.Allow)] into the controller, but this makes no difference unless I provide an empty {} json object in the body. This is not what I want.
Making BodyParams nullable - again, no change.
Adding .AddControllers(opt => opt.AllowEmptyInputInBodyModelBinding = true)... again, no change.
I Implemented the solution suggested here using the attribute modification in the comment by #HappyGoLucky. Again, this did not give the desired outcome, but it did change the response to : 400 - "The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true."
I tried modifying the solution in (4) to manually set context.HttpContext.Request.Body to an empty json object... but I can't figure out the syntax for this because it need to be a byte array and at that point I feel like I am way over complicating this.
How can I get the controller to use BodyParams with default values in the case that the user provides no body and no headers at all?
You can achieve that using a Minimal API.
app.MapGet("/data",
async (HttpRequest httpRequest) =>
{
var value = true;
if (Equals(httpRequest.GetTypedHeaders().ContentType, MediaTypeHeaderValue.Parse("application/json")))
{
var bodyParams = await httpRequest.ReadFromJsonAsync<BodyParams>();
if (bodyParams is not null) value = bodyParams.ValueOne;
}
var response = new {Message = "Hello", value};
return Results.Ok(response);
});
So, as there doesn't seem to be a more straightforward answer, I have currently gone with the approach number 5) from the OP, and just tweaking the code from there very slightly.
All this does is act as an action which checks the if the user has passed in any body json. If not, then it adds in an empty anonymous type. The behaviour then is to use the default True value from the BodyParams class.
The full code for the action class is:
internal class AllowMissingContentTypeForEmptyBodyConvention : Attribute, IActionModelConvention
{
public void Apply(ActionModel action)
{
action.Filters.Add(new AllowMissingContentTypeForEmptyBodyFilter());
}
private class AllowMissingContentTypeForEmptyBodyFilter : IResourceFilter
{
public void OnResourceExecuting(ResourceExecutingContext context)
{
if (!context.HttpContext.Request.HasJsonContentType()
&& (context.HttpContext.Request.ContentLength == default
|| context.HttpContext.Request.ContentLength == 0))
{
context.HttpContext.Request.ContentType = "application/json";
var str = new { };
//convert string to jsontype
var json = JsonConvert.SerializeObject(str);
//modified stream
var requestData = Encoding.UTF8.GetBytes(json);
context.HttpContext.Request.Body = new MemoryStream(requestData);
}
}
public void OnResourceExecuted(ResourceExecutedContext context)
{
// Do nothing
}
}
}
Then you can add this to any of your controllers using [AllowMissingContentTypeForEmptyBodyConvention]
I am using spring RestTemplate to download a file. The file size is small.
I want to get base64 encoded String. but I see the base64 encoded string is truncated from what it is supposed to be.
Here is my code
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(
new ByteArrayHttpMessageConverter());
StreamResourceReader reader = new StreamResourceReader();
restTemplate.execute(uri, HttpMethod.POST, null,
new StreamResponseExtractor(reader));
return reader.getEncodedString();
StreamResourceReader.java
public class StreamResourceReader {
private String encodeString;
public void read(InputStream content) {
try {
encodeString = Base64.encodeBase64String(IOUtils.toByteArray(content));
} catch (IOException e) {
throw new IllegalStateException(e);
}
}
public ByteArrayOutputStream getOutputStream(){
return outputStream;
}
public String getEncodedString() {
return encodeString;
}
}
StreamResponseExtractor.java
public class StreamResponseExtractor implements ResponseExtractor<InputStream> {
private StreamResourceReader reader;
public StreamResponseExtractor(StreamResourceReader resourceReader) {
this.reader=resourceReader;
}
#Override
public InputStream extractData(ClientHttpResponse response) throws IOException {
reader.read(response.getBody());
return null;
}
}
EDIT
just found out that inputStream is truncated. I dont know why and what the fix is. any help here would be appreciated.
Thanks
To confirm if your input stream is indeed truncated you can try few things. What IOUtils.toByteArray(content) does is buffers internally the content of input stream and returns the buffer. You can compare the length of buffer array with the byte array the file actually represents. You can do latter with below code
String filePath = "/test.txt";
byte[] fileByteArray= Files.readAllBytes(Paths.get(filePath));
Also ClientHttpResponse ( client view of http response) too has the inputstream available which you can check for content.
InputStream getBody() throws IOException;
As a test for this scenario , I created spring boot Rest client using Rest Template (using the code you shared) and a service for file download again using Spring Boot. On comparing the base encoded String from download vs direct file access, both return same content (compared using String equals method).
UPDATE: Another thing worth trying is just use java.net.HttpURLConnection
in a simple program (for help see here) and try to download the content and check whether this works properly because behind all the Spring abstractions, in this case the underlying object used is HttpURLConnection only
SimpleClientHttpResponse extends AbstractClientHttpResponse {
public InputStream getBody() throws IOException {
InputStream errorStream = this.connection.getErrorStream();
this.responseStream = (errorStream != null ? errorStream : this.connection.getInputStream());
return this.responseStream;
}
...........
...........
}
If this also gives you the same issue, then it's time to look at the server side. May be the server is not sending the complete data.
In a web api method I am generating a file and then streaming it to the response like so
public async Task<HttpResponseMessage> GetFile() {
FileInfo file = generateFile();
var msg = Request.CreateResponse(HttpStatusCode.OK);
msg.Content = new StreamContent(file.OpenRead());
msg.Content.Headers.ContentType = new MediaTypeHeaderValue("application/pdf");
msg.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment") {FileName = file.Name};
return msg;
}
because this a generated file I want to delete it after the response has finished streaming but I can't seem to find a hook in the pipeline for this.
I suppose that I can put a reference to the file in a static and set up a custom MessageHandler that pulls values out of this same static variable and deletes. However, this seems like it can't possibly be right both because of the use of a static (when this should all be per-request) and because I'd have to register a separate route.
I've seen this question but it seems to not really have much of a useful response.
Nice scenario!...the problem with using message handlers is that response writing happens at the host layers and below message handlers layer, so they are not ideal...
Following is an example of how you could do it:
msg.Content = new CustomStreamContent(generatedFilePath);
public class CustomStreamContent : StreamContent
{
string filePath;
public CustomStreamContent(string filePath)
: this(File.OpenRead(filePath))
{
this.filePath = filePath;
}
private CustomStreamContent(Stream fileStream)
: base(content: fileStream)
{
}
protected override void Dispose(bool disposing)
{
//close the file stream
base.Dispose(disposing);
try
{
File.Delete(this.filePath);
}
catch (Exception ex)
{
//log this exception somewhere so that you know something bad happened
}
}
}
By the way, are you generating this file because you are converting some data into PDF. If yes, then I think you could use PushStreamContent for this purpose by directly writing the converted data into the response stream. This way you need not generate a file first and then worry about deleting it later.
We performed same action in WebAPI. I needed to delete file just after it downloaded form server.
We can create custom response message class. It takes file path as parameter and delete it once its transmitted.
public class FileResponseMessage : HttpResponseMessage
{
private readonly string _filePath;
public FileHttpResponseMessage(string filePath)
{
this._filePath= filePath;
}
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
Content.Dispose();
File.Delete(_filePath);
}
}
Use this class as below code and it will delete your file once it will be written on response stream.
var response = new FileResponseMessage(filePath);
response.StatusCode = HttpStatusCode.OK;
response.Content = new StreamContent(new FileStream(filePath, FileMode.Open, FileAccess.Read));
response.Content.Headers.ContentDisposition = new ContentDispositionHeaderValue("attachment")
{
FileName = "MyReport.pdf"
};
return response;
is there any way to validate a string to be json or not ? other than try/catch .
I'm using ServiceStack Json Serializer and couldn't find a method related to validation .
Probably the quickest and dirtiest way is to check if the string starts with '{':
public static bool IsJson(string input){
input = input.Trim();
return input.StartsWith("{") && input.EndsWith("}")
|| input.StartsWith("[") && input.EndsWith("]");
}
Another option is that you could try using the JavascriptSerializer class:
JavaScriptSerializer ser = new JavaScriptSerializer();
SomeJSONClass = ser.Deserialize<SomeJSONClass >(json);
Or you could have a look at JSON.NET:
http://james.newtonking.com/projects/json-net.aspx
http://james.newtonking.com/projects/json/help/index.html?topic=html/SerializingJSON.htm
A working code snippet
public bool isValidJSON(String json)
{
try
{
JToken token = JObject.Parse(json);
return true;
}
catch (Exception ex)
{
return false;
}
}
Source
You can find a couple of regular expressions to validate JSON over here: Regex to validate JSON
It's written in PHP but should be adaptable to C#.
What is the best way to return XML from a controller's action in ASP.NET MVC? There is a nice way to return JSON, but not for XML. Do I really need to route the XML through a View, or should I do the not-best-practice way of Response.Write-ing it?
return this.Content(xmlString, "text/xml");
Use MVCContrib's XmlResult Action.
For reference here is their code:
public class XmlResult : ActionResult
{
private object objectToSerialize;
/// <summary>
/// Initializes a new instance of the <see cref="XmlResult"/> class.
/// </summary>
/// <param name="objectToSerialize">The object to serialize to XML.</param>
public XmlResult(object objectToSerialize)
{
this.objectToSerialize = objectToSerialize;
}
/// <summary>
/// Gets the object to be serialized to XML.
/// </summary>
public object ObjectToSerialize
{
get { return this.objectToSerialize; }
}
/// <summary>
/// Serialises the object that was passed into the constructor to XML and writes the corresponding XML to the result stream.
/// </summary>
/// <param name="context">The controller context for the current request.</param>
public override void ExecuteResult(ControllerContext context)
{
if (this.objectToSerialize != null)
{
context.HttpContext.Response.Clear();
var xs = new System.Xml.Serialization.XmlSerializer(this.objectToSerialize.GetType());
context.HttpContext.Response.ContentType = "text/xml";
xs.Serialize(context.HttpContext.Response.Output, this.objectToSerialize);
}
}
}
If you're building the XML using the excellent Linq-to-XML framework, then this approach will be helpful.
I create an XDocument in the action method.
public ActionResult MyXmlAction()
{
// Create your own XDocument according to your requirements
var xml = new XDocument(
new XElement("root",
new XAttribute("version", "2.0"),
new XElement("child", "Hello World!")));
return new XmlActionResult(xml);
}
This reusable, custom ActionResult serialises the XML for you.
public sealed class XmlActionResult : ActionResult
{
private readonly XDocument _document;
public Formatting Formatting { get; set; }
public string MimeType { get; set; }
public XmlActionResult(XDocument document)
{
if (document == null)
throw new ArgumentNullException("document");
_document = document;
// Default values
MimeType = "text/xml";
Formatting = Formatting.None;
}
public override void ExecuteResult(ControllerContext context)
{
context.HttpContext.Response.Clear();
context.HttpContext.Response.ContentType = MimeType;
using (var writer = new XmlTextWriter(context.HttpContext.Response.OutputStream, Encoding.UTF8) { Formatting = Formatting })
_document.WriteTo(writer);
}
}
You can specify a MIME type (such as application/rss+xml) and whether the output should be indented if you need to. Both properties have sensible defaults.
If you need an encoding other than UTF8, then it's simple to add a property for that too.
If you are only interested to return xml through a request, and you have your xml "chunk", you can just do (as an action in your controller):
public string Xml()
{
Response.ContentType = "text/xml";
return yourXmlChunk;
}
There is a XmlResult (and much more) in MVC Contrib. Take a look at http://www.codeplex.com/MVCContrib
I've had to do this recently for a Sitecore project which uses a method to create an XmlDocument from a Sitecore Item and its children and returns it from the controller ActionResult as a File. My solution:
public virtual ActionResult ReturnXml()
{
return File(Encoding.UTF8.GetBytes(GenerateXmlFeed().OuterXml), "text/xml");
}
use one of these methods
public ContentResult GetXml()
{
string xmlString = "your xml data";
return Content(xmlString, "text/xml");
}
or
public string GetXml()
{
string xmlString = "your xml data";
Response.ContentType = "text/xml";
return xmlString;
}
Finally manage to get this work and thought I would document how here in the hopes of saving others the pain.
Environment
VS2012
SQL Server 2008R2
.NET 4.5
ASP.NET MVC4 (Razor)
Windows 7
Supported Web Browsers
FireFox 23
IE 10
Chrome 29
Opera 16
Safari 5.1.7 (last one for Windows?)
My task was on a ui button click, call a method on my Controller (with some params) and then have it return an MS-Excel XML via an xslt transform. The returned MS-Excel XML would then cause the browser to popup the Open/Save dialog. This had to work in all the browsers (listed above).
At first I tried with Ajax and to create a dynamic Anchor with the "download" attribute for the filename,
but that only worked for about 3 of the 5 browsers(FF, Chrome, Opera) and not for IE or Safari.
And there were issues with trying to programmatically fire the Click event of the anchor to cause the actual "download".
What I ended up doing was using an "invisible" IFRAME and it worked for all 5 browsers!
So here is what I came up with:
[please note that I am by no means an html/javascript guru and have only included the relevant code]
HTML (snippet of relevant bits)
<div id="docxOutput">
<iframe id="ifOffice" name="ifOffice" width="0" height="0"
hidden="hidden" seamless='seamless' frameBorder="0" scrolling="no"></iframe></div>
JAVASCRIPT
//url to call in the controller to get MS-Excel xml
var _lnkToControllerExcel = '#Url.Action("ExportToExcel", "Home")';
$("#btExportToExcel").on("click", function (event) {
event.preventDefault();
$("#ProgressDialog").show();//like an ajax loader gif
//grab the basket as xml
var keys = GetMyKeys();//returns delimited list of keys (for selected items from UI)
//potential problem - the querystring might be too long??
//2K in IE8
//4096 characters in ASP.Net
//parameter key names must match signature of Controller method
var qsParams = [
'keys=' + keys,
'locale=' + '#locale'
].join('&');
//The element with id="ifOffice"
var officeFrame = $("#ifOffice")[0];
//construct the url for the iframe
var srcUrl = _lnkToControllerExcel + '?' + qsParams;
try {
if (officeFrame != null) {
//Controller method can take up to 4 seconds to return
officeFrame.setAttribute("src", srcUrl);
}
else {
alert('ExportToExcel - failed to get reference to the office iframe!');
}
} catch (ex) {
var errMsg = "ExportToExcel Button Click Handler Error: ";
HandleException(ex, errMsg);
}
finally {
//Need a small 3 second ( delay for the generated MS-Excel XML to come down from server)
setTimeout(function () {
//after the timeout then hide the loader graphic
$("#ProgressDialog").hide();
}, 3000);
//clean up
officeFrame = null;
srcUrl = null;
qsParams = null;
keys = null;
}
});
C# SERVER-SIDE (code snippet)
#Drew created a custom ActionResult called XmlActionResult which I modified for my purpose.
Return XML from a controller's action in as an ActionResult?
My Controller method (returns ActionResult)
passes the keys parameter to a SQL Server stored proc that generates an XML
that XML is then transformed via xslt into an MS-Excel xml (XmlDocument)
creates instance of the modified XmlActionResult and returns it
XmlActionResult result = new XmlActionResult(excelXML, "application/vnd.ms-excel");
string version = DateTime.Now.ToString("dd_MMM_yyyy_hhmmsstt");
string fileMask = "LabelExport_{0}.xml";
result.DownloadFilename = string.Format(fileMask, version);
return result;
The main modification to the XmlActionResult class that #Drew created.
public override void ExecuteResult(ControllerContext context)
{
string lastModDate = DateTime.Now.ToString("R");
//Content-Disposition: attachment; filename="<file name.xml>"
// must set the Content-Disposition so that the web browser will pop the open/save dialog
string disposition = "attachment; " +
"filename=\"" + this.DownloadFilename + "\"; ";
context.HttpContext.Response.Clear();
context.HttpContext.Response.ClearContent();
context.HttpContext.Response.ClearHeaders();
context.HttpContext.Response.Cookies.Clear();
context.HttpContext.Response.Cache.SetCacheability(System.Web.HttpCacheability.NoCache);// Stop Caching in IE
context.HttpContext.Response.Cache.SetNoStore();// Stop Caching in Firefox
context.HttpContext.Response.Cache.SetMaxAge(TimeSpan.Zero);
context.HttpContext.Response.CacheControl = "private";
context.HttpContext.Response.Cache.SetLastModified(DateTime.Now.ToUniversalTime());
context.HttpContext.Response.ContentType = this.MimeType;
context.HttpContext.Response.Charset = System.Text.UTF8Encoding.UTF8.WebName;
//context.HttpContext.Response.Headers.Add("name", "value");
context.HttpContext.Response.Headers.Add("Last-Modified", lastModDate);
context.HttpContext.Response.Headers.Add("Pragma", "no-cache"); // HTTP 1.0.
context.HttpContext.Response.Headers.Add("Expires", "0"); // Proxies.
context.HttpContext.Response.AppendHeader("Content-Disposition", disposition);
using (var writer = new XmlTextWriter(context.HttpContext.Response.OutputStream, this.Encoding)
{ Formatting = this.Formatting })
this.Document.WriteTo(writer);
}
That was basically it.
Hope it helps others.
A simple option that will let you use streams and all that is return File(stream, "text/xml");.
Here is a simple way of doing it:
var xml = new XDocument(
new XElement("root",
new XAttribute("version", "2.0"),
new XElement("child", "Hello World!")));
MemoryStream ms = new MemoryStream();
xml.Save(ms);
return File(new MemoryStream(ms.ToArray()), "text/xml", "HelloWorld.xml");
A small variation of the answer from Drew Noakes that use the method Save() of XDocument.
public sealed class XmlActionResult : ActionResult
{
private readonly XDocument _document;
public string MimeType { get; set; }
public XmlActionResult(XDocument document)
{
if (document == null)
throw new ArgumentNullException("document");
_document = document;
// Default values
MimeType = "text/xml";
}
public override void ExecuteResult(ControllerContext context)
{
context.HttpContext.Response.Clear();
context.HttpContext.Response.ContentType = MimeType;
_document.Save(context.HttpContext.Response.OutputStream)
}
}