We've seen a number of posts relating to JSON data returns via WCF, but they all cover the aspect of converting object to JSON and then returning that object converted to JSON via the magic of attributes.
We've got a number of preformatted JSON files that we want to return via an WCF service. Essentially all we need to do is read the files in (or a cached copy of of the file) and then return the data as a string . I think ... It seems wasteful to read in the JSON file, serialize it to an object then deserialize back to JSON.. Any help on this?
When using the WebHttpBinding, this is as simple as creating a WebGet annotated method with a Stream return type:
[WebGet]
public Stream GetFile(Int32 someId)
{
//your logic to lookup or create the file here.
//Open the file (a MemoryStream would be acceptible as well if you were creating the data on the fly
Stream stream = File.OpenRead(yourFilePath);
//register an event to clean up the temporary file (if necessary)
OperationContext.Current.OperationCompleted += (s, e) =>
{
File.Delete(yourFilePath);
};
return stream;
}
Related
I have a requirement where one or more spring cloud stream kafka-streams bindings need to be created based on dynamic configuration. By dynamic config I mean stream bindings (input-output) will be specified run-time. Either via external property file or from database.
E.g We need to create multiple stream processors where input output topic pairs and relevant configs are provided. Then code should loop through this config create and start those bindings.
In spring cloud stream we write this in a java file
#StreamListener(StreamBindings.INPUT)
#SendTo(StreamBindings.OUTPUT)
public KStream<String,String> process(KStream<String,String> inputStream) {
return inputStream
.map( ... )
.selectKey( ... )
.mapValues( ... );
}
Where StreamBindings is like
public interface StreamBindings {
String INPUT = "input-topic";
String OUTPUT = "output-topic";
#Input(INPUT)
KStream<String,String> inputStream();
#Input(OUTPUT)
KStream<String,String> outputStream();
}
Now I want a piece of code to create this in run-time based on info I specified above.
Can this be done and how? And can we specify body of process function as an argument, like some kind of message handler?
I might be confused about something, but when I store a custom object from the Java Riak client and then try to read that object using the Python Riak client, I end up with a raw json string instead of a dict.
However, if I store a the object in python, I am able to output a python dictionary when fetching that object.
I could simply use a json library on the python side to resolve this, but the very fact that I am experiencing this discrepancy makes me think that I am doing something wrong.
On the Java side, this is my object:
class DocObject
{
public String status; // FEEDING | PERSISTED | FAILED | DELETING
public List<String> messages = new ArrayList<String>();
}
class PdfObject extends DocObject
{
public String url;
public String base_url;
}
This is how I am storing that object in Riak:
public void feeding(IDocument doc) throws RiakRetryFailedException {
PdfObject pdfObject = new PdfObject();
pdfObject.url = doc.getElement("url").getValue().toString();
pdfObject.base_url = doc.getElement("base_url").getValue().toString();
pdfObject.status = "FEEDING";
String key = hash(pdfObject.url);
pdfBucket.store(key, pdfObject).execute();
}
And this is what I am doing in Python to fetch the data:
# Connect to Riak.
client = riak.RiakClient()
# Choose the bucket to store data in.
bucket = client.bucket('pdfBucket')
doc = bucket.get('7909aa2f84c9e0fded7d1c7bb2526f54')
doc_data = doc.get_data()
print type(doc_data)
The result of the above python is:
<type 'str'>
I am expecting that to be <type 'dict'>, just like how the example here works:
http://basho.github.com/riak-python-client/tutorial.html#getting-single-values-out
I am perplexed as to why when the object is stored from Java it is stored as a JSON string and not as an object.
I would appreciate if anybody could point out an issue with my approach that might be causing this discrepancy.
Thanks!
It would appear you've found a bug in our Python client with the HTTP protocol/transport.
Both the version you're using and the current one in master are not decoding JSON properly. Myself and another dev looked into this this morning and it appears to stem from an issue with charset parameter being returned from Riak with the content-type as Christian noted in his comment ("application/json; charset=UTF-8")
We've opened an issue on github (https://github.com/basho/riak-python-client/issues/227) and will get this corrected.
In the mean time the only suggestion I have is to decode the returned JSON string yourself, or using the 1.5.2 client (latest stable from pypy) and the Protocol Buffers transport:
client = riak.RiakClient(port=8087, transport_class=riak.RiakPbcTransport)
it will return the decoded JSON as a dict as you're expecting.
If a query string param exists in my page request I want to query the database on the server in the Page_Load and then return the result to the client. I can do the query string param check and query the DB but how do I return the data to the page and on the javascript side how do I access that data?
Ideally I would return JSON of an object structure and it would be returning an array of them.
Yes, returning JSON would be the best option. I'm not sure how you query your database (Do you use LINQ or ADO.NET DataTables, etc)
If you don't have custom object of type you want to send, I recommend you create one. Then you should get an array of them.
Example:
public class Person {
string Name { get; set; }
int Age { get; set; }
}
Person[] pArr = new Person[5];
Then you can use a third party library like this to create an string representaion of that array in JSON.
string json = JsonConvert.SerializeObject(product);
Then you write that json string to the Response object so its sent down to the client, by overriding the Render method of the page.
// Don't expect this code to work as it is, but take this as a guidance
Response.Clear();
Response.Write(json);
Response.Close();
on the client side use jQuery library send a request to page, and process the JSON response for you.
$.getJSON('url', function(data) {
//process data
});
Here is my suggestion if you don't want to use an AJAX request for this:
Use the objects as you would normally do in the page_load, and convert it to a JSON string as explained above.
Then use ClientScriptManager to create an JavaScript variable on the client side when it loaded.
ClientScript.RegisterClientScriptBlock(typeof(Page), "unique_key", "var myObjectList = " + json, true);
After this when the page loads you will have an variable named "myObjectList" with the list of objects without having to make a different AJAX call.
You can directly refer that variable in your javascript and do necessary processing.
Hope this helps.
I've got a legacy web service which I'd like to wrap with a new MVC Web API, question is can I get the ASP.NET Web API to convert my xml into json?
A thought that I had was to use XDocument to create a dynamic object and return that, but when I tried it with an ExpandoObject unfortunately it returned a json object with Key/Value pairs.
Using json.NET you can do it easily:
string result = Newtonsoft.Json.JsonConvert.SerializeXmlNode(xmldocument);
Download Newtonsoft.Json at http://james.newtonking.com/pages/json-net.aspx
You could. One way to do it would be to deserialize the XML into objects and then serialize them again into JSON.
A more efficient (though harder to code up approach) would be to write your own xml-to-json "transcriber" that reads in the XML and spits out JSON.
Just note that not all XML can be represented easily as JSON.
Turns out this can be done by converting an XDocument to a dynamic JsonObject like so roughly:
var doc = XDocument.Load(uri);
foreach (var node in doc.Root.Descendants()) {
var obj = (dynamic) new JsonObject();
foreach (var child in node.Descendants())
{
obj[child.Name.LocalName] = child.Value;
yield return obj;
}
}
In WebApiConfig file inside Register function add the below code at last (WebApiConfig file is at App_Start folder)
config.Formatters.JsonFormatter.SupportedMediaTypes.Add(new System.Net.Http.Headers.MediaTypeHeaderValue("text/html"));
config.Formatters.Remove(config.Formatters.XmlFormatter);
I have a simple webservice that I would like to upload a file to. The problem is that I need the response in json.
Form my experience in order to get a response in Json my request has to have a content-type of 'application/json'. But ofcourse this cannot be the case with a file upload since the content type will have to be 'multipart/form-data'.
In my Json i want to return a value showing whether successful and a filename.
[WebMethod(EnableSession = true)]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public TyoeOfSomeObject UploadFile()
{
// Get the file from the context and do something with it
HttpPostedFile httpPostedFile = HttpContext.Current.Request.Files[0];
// Return either a string or an object to serialise with the required values
return SomeObject;
}
I was having the same issue, and resolved it by setting the response's ContentType and calling the response's Write() function:
C#
String j = jsonParser.AsJson(obj);
Context.Response.ContentType = "application/json; charset=utf-8";
Context.Response.Write(j);
VB
Dim j As String = jsonParser.AsJson(obj)
Context.Response.ContentType = "application/json; charset=utf-8"
Context.Response.Write(j)
You could set the return type of your function to a string and then use some JSON serializer to serialize your object to JSON and return it as a JSON string. For JSON serialization I use Jayrock I believe ASP .NET has its own JSON libraries now as well.
You can declare your web method with byte[] as an output parameter. Then you can set ContentType and return any data you want.
If you use WCF instead of ASMX web service you can return Stream or Message in such cases (see Returning raw json (string) in wcf. You can try also return Stream instead of byte[] in the web service if your file is very large. Probably it will also works with ASMX web service.
ASP.Net Webservice Serialization
I was unable to find a way to return a response in json. I don't think its possible without tinkering with the inner workings. The solution I used was to create an aspx that could handle the file, you could ofcourse use .ashx or WCF as described by OLEG.