I know returning types in a wcv service is allowed, and it will convert the object to json. But what if I don't want to return a random type, but return a string with formatted json? I can construct json my self but it can a) be messy, and b) not auto encode html values.
How do I do build a custom formatted json string? Off the top of my had, can I return a dictionary with key, value pairs? Will the value be encoded so you can transmitted without running the risk of malformed json?
Have a look at JSON.Net. I've used it in the past for serializing/deserializing to/from Json. It also (according to the web page) has support for converting Json to/from XML, so it seems reasonable that there would be some functions in there to build arbitrary Json strings in a way that is less error-prone than doing it yourself.
You can specify a return type of object and then use an anonymous type to return an arbitrary object. If you want to return an arbitrary collection, you can return IEnumerable, and use that to return a collection of anonymous types.
as far as I can understand, you want a webservice that returns a string that can be parsed using json (like JSON.parse(yourReturnedString)... As ckramer answered, JSON.NET can help to format your whatever dictionary into json but you should know dictionary is "json-serialised" as key:'your key', value:'your value§that can be also an object that will be serialized', so if you are using JSON.NET, you should also once it has been deserialezed, remove all the "key": and ,"value" JSON.NET returned.
so good so far you should definetely declare your webmethod as a method that returns a JSON format.
hope you found a solution before this answer...
Related
I have an iterable of People that I save as a string after converting from json. I want to know how would I convert the string back to a list.
// Save data
val peopleString = myList.toString()
// String saved is
[People(name=john, age=23), People(name=mary, age=21), People(name=george, age=11)]
Now is it possible to convert peopleString back to a list?
val peopleList: List<People> = peopleString.?
In short, no... kind of.
Your output is not JSON, and toString() is the wrong function to use if you wanted JSON. The output of toString() is not a proper serialization format that can be understood and used to rebuild the original data structure.
Converting a data structure into some format so that it can be transmitted and later rebuilt is known as serialization. Kotlin has a serializer which can serialize objects into a number of different formats, including JSON: https://github.com/Kotlin/kotlinx.serialization#quick-example.
It's not as easy to use as toString(), but that's to be expected as toStrings's purpose is very different from serialization.
I have a Mongo collection annotated with #Document and I want the possibility to also get that Java object from a String (JSON) as we're getting these classes pushed into a queue as String.
Is there a method in Spring-Data-Mongo which converts from JSON to the actual Document object?
#Autowired
MongoTemplate mongoTemplate;
and then
mongoTemplate.getConverter().read(MatchMongo.class, (DBObject) JSON.parse(json));
Thanks to freakman, your answer helped a lot
You can try com.mongodb.util.JSON.parse() method. It returns object so you probably have to do the casting + it may be it need "class" field inside json string.
I need to serialize a (possibly complex *) object so that I can calculate the object's MAC**.
If your messages are strings you can simply do tag := MAC(key, string) and with very high probability if s1 != s2 then MAC(key, s1) != MAC(key, s2), moreover it is computationally hard to find s1,s2 such that MAC(k,s1) == MAC(k,s2).
Now my question is, what happens if instead of strings you need do MAC a very complex object that can contain arrays of objects and nested objects:
JSON
Initially I though that just using JSON serialization could do the trick but it turns out that JSON serializers do not care about order so for example: {b:2,a:1} can be serialized to both {"b":2,"a":1} or {"a":2,"b":1}.
URL Params
You can convert the object to a list of url query params after sorting the keys, so for example {c:1,b:2} can be serialized to b=2&c=1. The problem is that as the object gets more complex the serialization becomes difficult to understand. Example: {c:1, b:{d:2}}
1. First we serialize the nested object:{c:1, b:{d=2}}
2. Then url encode the = sign: {c:1, b:{d%3D2}}
3. Final serialization is: b=d%3D2&c=1
As you can see, the serialization quickly becomes unreadable and though I have not proved it yet I also have the feeling that it is not very secure (i.e. it is possible to find two messages that MAC to the same value)
Can anyone show me a good secure*** algorithm for serializing objects?
[*]: The object can have nested objects and nested arrays of objects. No circular references allowed. Example:
{a:'a', b:'b', c:{d:{e:{f:[1,2,3,4,5]}}, g:[{h:'h'},{i:'i'}]}}
[**]: This MAC will then be sent over the wire. I cannot know what languages/frameworks are supported by the servers so language specific solutions like Java Object Serialization are not possible.
[***]: Secure in this context means that given messages a,b: serialize(a) = serialize(b) implies that a = b
EDIT: I just found out about the SignedObject through this link. Is there a language agnostic equivalent?
What you are looking for is a canonical representation, either for the data storage itself, or for pre-processing before applying the MAC algorithm. One rather known format is the canonicalization used for XML-signature. It seems like the draft 2.0 version of XML signature is also including HMAC. Be warned that creating a secure verification of XML signatures is fraught with dangers - don't let yourself be tricked into trusting the signed document itself.
As for JSON, there seems to be a canonical JSON draft, but I cannot see the status of it or if there are any compliant implementations. Here is a Q/A where the same issue comes up (for hashing instead of a MAC). So there does not seem to be a fully standardized way of doing it.
In binary there's ASN.1 DER encoding, but you may not want to go into that as it is highly complex.
Of course you can always define your own binary or textual representation, as long as there is one representation for data sets that are semantically identical. In the case of an textual representation, you will still need to define a specific character encoding (UTF-8 is recommended) to convert the representation to bytes, as HMAC takes binary input only.
Here is the json that I am struggling to recreate. :
WorkLoadResult({
"AreaReturned":[
{
"ResultCode":"0"
}
],
"Process":"Generic",
"WorkLoadId":"megaupload_server_798811",
"Status":"1",
"TotalSuccessfulRuns":"3"
});
I have all of this created just perfectly in my code rolling my class into another class. I have been attempting to create the WorkLoadResult header ( I know this really isn't a header but for lack of a better word I will call it this), but I don't see how this can even be created. When I run this through a JSON formatter the JSON is determined to be valid. This is something I am receiving back from a webservice. I in turn need to have a class created in order to catch this JSON. I have looked at multiple different json examples and see no examples that have JSON formatted in this manner with some sort of a header at the beginning of the data.
My one current option is to strip this out of the data prior to doing pushing it into a class. I do not like this option and have to think that it is possible to have this WorkLoadResult in my class.
Quite new to JSON, any advice/direction is greatly appreciated.
Thanks.
This looks like a JSONP response. If the webservice returns exactly this string and you can't tell the webservice to return plain JSON, you have no choice but removing the function call around the real JSON object.
I am returning a list of items (user defined class) in a REST service using WCF. I am returning the items as JSON and it is used in some client side javascript (so the 'schema' of the class was derived from what the javascript library required). The class is fairly basic, strings and a bool. The bool is optional, so if it is absent the javascript library uses a default value, and if it is present (true or false) the value is used.
The problem is if I use a bool, the value is defaulted to false when serialized, and if i use a bool?, the member is still sent accross in the JSON and defaulted to null which causes problems with the library (it wont fall back to the default value).
I know I can probably mess around the the javascript library, but I would like to find a way to just not send any members which are null so they dont show up in the serialized JSON at all.
Any ideas?
You could do a little bit of packing and unpacking before and after the serialization. E.g.:
You could make two different versions
of the class, one with and one
without the bool, and convert as
appropriate before and after
transmitting. (sends the least amount
of data, if # of bytes is a greater
consideration than code complexity)
You could add another bool that tells
whether the first bool is supposed to
be null.