I am adding an API to an existing database so I am stuck with the current MongoDB document schema. The document is flat with no nested objects. I want to deserialize a group of the fields into a child object. I was wondering if there was a way of doing that with the BsonElement attribute? Another approach I came across was using a custom serializer. Would it be possible to write a custom serializer for the child object even though there is no field matching the child object's name? Or would I need to write the custom serializer at using the parent object?
Here is an example of a document:
{
"Name": "Name",
"AddressLine1": "321 street",
"AddressLine2": "apt 1",
}
Here is an example of the C# classes and what I was trying to do:
public class Customer
{
[BsonElement("Name")]
public string CustomerName {get; set;}
public Address Address {get; set;}
}
public class Address
{
[BsonElement("AddressLine1")]
public string AddressLine1 {get; set;}
[BsonElement("AddressLine2")]
public string AddressLine2 {get; set;}
}
There's no way to use attributes to achieve what you are wanting, this because the attributes apply given conditions to a BsonMemberMap which resides in the BsonClassMap.
As you said this however can be achieved by creating a custom serializer.
public class CustomBsonSerializer : IBsonSerializer<MyType>
{
}
BsonSerializer.RegisterSerializer(new CustomBsonSerializer())
However, if you want to write a bespoke serializer it can become a bit brittle.
I'd personally opt for creating 2 sets of models, one to model the current state of your documents in MongoDB and then another model to create the structure that you want to use.
In an ASP.NET Core controller method, which has a parameter of type dynamic, I would like to map using Automapper as shown below. The method looks like this:
public IActionRsult Post([FromBody] dynamic model) {
// Skip validation
switch(model.src) {
case "employer"
var employerVM = _mapper.Map<EmployerViewModel>(model.data);
// Work with mapped object
break;
case "employee"
var employeeVM = _mapper.Map<EmployeeViewModel>(model.data);
// Work with mapped object
break;
}
}
where EmployerViewModel looks like this:
public class EmployerViewModel {
public string CompanyName {get; set;}
public string CompanyAddress {get; set;}
}
and EmployeeViewModel looks like this:
public class EmployeeViewModel {
public string FirstName {get; set;}
public string LastName {get; set;}
public bool Ready {get; set;}
}
It receives JSON data from the client side, which may look like this:
{
"src": "employer",
"data": {
"CompanyName": "Pioneers Ltd.",
"CompanyAddress": "126 Schumacher St., London"
}
}
or this:
{
"src": "employee",
"data": {
"FirstName": "John",
"LastName": "Doe",
"Ready": true
}
}
Now everything works fine except for boolean properties, which are always set to false no matter what the value in JSON is. I have JSON input formatter, which constructs the instances in the parameter. I've checked the type of the instances and found them to be Newtonsoft.Json.Linq.JObject
Any idea how I can get bools to behave correctly?
I would like to continue supporting mapping an arbitrary number of destination classes using the TDestination IMapper.Map<TDestination>(object source) (see here) without having to explicitly construct AutoMapper maps for each. Any hint how this can be achieved?
P.S. I'm using AutoMapper 6.2.1 and ASP.NET Core 1.1.3
The problem is that JObject wraps its content in JValue, so it cannot work by default with AM which of course expects the actual values. So you have to let AM know how to map a JValue:
cfg.CreateMap<JValue, object>().ConvertUsing(source => source.Value);
I need to get my JSON output looking like this:
{
"User": {
"Id" : "1",
"FirstName" : "John",
"LastName" : "Doe",
... etc
My first issue is that the class name being serialized here is called Person not User, and I am not able to change that. But the JSON needs User.
Secondly, my Web API method is not returning a root node here at all, what exactly am I doing wrong?
My JSON looks like this:
{"Id":1,"BossId":null,"Title":"CEO","GivenName":"Doe", ... etc
This is so badly formatted that even my Chrome extension to make JSON pretty doesn't recognize this stuff.
Here's my Web API controller to get a user by ID, which is resulting in the above:
[Route("{id:int}")]
public HttpResponseMessage GetPerson(int id) {
Person person = repository.Get(id);
if (person == null) {
throw new HttpResponseException(HttpStatusCode.NotFound);
}
return Request.CreateResponse(HttpStatusCode.OK, person);
}
I am also going to have to map class properties to different names here, which is a separate issue.
For example, the class has GivenName and FamilyName but the JSON needs FirstName and LastName. Is there an attribute I can apply to the property for this?
Any help would be appreciated.
ASP.NET WebApi uses JSON.NET for serialization to json. So you can change name in this way:
class Person
{
[JsonProperty(PropertyName = "LastName")]
public string FamilyName { get; set; }
...
}
EDIT
For add root element look at this answer. I didn't try this but looks nice.
Assuming you are using the Newtonsoft Json.Net, the most popular .Net Json serializer, following modifications are required:
Wrap the Person object inside a wrapper and assign a JsonProperty to it:
[JsonObject]
public class Wrapper
{
[JsonProperty("User")]
public Person Person {get; set;}
}
Now use the same JsonProperty inside the Person class too:
[JsonObject]
public class Person
{
[JsonProperty("FirstName")]
public string GivenName {get; set;}
[JsonProperty("LastName")]
public string FamilyName {get; set;}
... More Properties
}
Now while filling the response.following need to be done:
Wrapper w = new Wrapper();
w.Person = <assign Value>
return Request.CreateResponse(HttpStatusCode.OK, w);
One last thing Json unlike XML doesn't have a concept of a root node, it's nameless, that's why wrapper doesn't come anywhere and it would start from first object marked as User in this case, Json is a like an anonymous type in C#, internally a Key Value pair, since Keys are always string
I have a class defined as follows:
class Person
{
public String Id { get; set; }
public String Name { get; set; }
public Person Mother { get; set; }
}
I've implemented a custom serializer for the Mother property to serialize the Id only. The final BSON would look something like this:
[{
"_id": "54df1095fa0bd7122cb2c550",
"name": "John",
"mother": { "_id": "54df1095fa0bd7122cb2c551" }
}]
If I try to execute a query to find a person with a given mother as follows:
var results = await collection.Find<Person> (p => p.Mother.Id == "...").ToListAsync ();
The driver complains with the following:
{"Unable to determine the serialization information for the expression: p.Mother.Id."}
Is there a way to add serialization info to the driver so it knows to call my custom serializer to deserialize Person for this type of query?
Yes, there are two interfaces you may implement to provide serialization information. IBsonDocumentSerializer and IBsonArraySerializer. In this case, you'll want to implement IBsonDocumentSerializer on your customer serializer and handle the GetMemberSerializationInfo call for the memberName Id.
Finding some difficulty in sourcing information in trying to deserialize JSON in C#.
I have results from Google custom search returned in JSON format. I just want to check through my steps and establish the order in trying to deserialize it. Is this right?
I need to create classes to match
the JSON format. Kind of like a
creating schema file.
Use the JavaScriptSerializer() class and
deserialize method to extract the
relevant bits.
One of the issues I think I am going to run into is that I don't require all of the data returned but only the html links. How can I achieve that?
UPDATE
I have updated my question with the following JSON snippet and C# code. I want to output the string 'links' to console but it doesn't seem to be working. I think I am defining my classes wrongly?
JSON from Google Custom Search
handleResponse({
"kind": "customsearch#search",
"url": {
"type": "application/json",
"template": "https://www.googleapis.com/customsearch/v1?q\u003d{searchTerms}&num\u003d{count?}&start\u003d{startIndex?}&hr\u003d{language?}&safe\u003d{safe?}&cx\u003d{cx?}&cref\u003d{cref?}&sort\u003d{sort?}&alt\u003djson"
},
"queries": {
"nextPage": [
{
"title": "Google Custom Search - lectures",
"totalResults": 9590000,
"searchTerms": "lectures",
"count": 1,
"startIndex": 2,
"inputEncoding": "utf8",
"outputEncoding": "utf8",
"cx": "017576662512468239146:omuauf_lfve"
}
],
"request": [
{
"title": "Google Custom Search - lectures",
"totalResults": 9590000,
"searchTerms": "lectures",
"count": 1,
"startIndex": 1,
"inputEncoding": "utf8",
"outputEncoding": "utf8",
"cx": "017576662512468239146:omuauf_lfve"
}
]
},
"context": {
"title": "Curriculum",
"facets": [
[
{
"label": "lectures",
"anchor": "Lectures"
}
],
[
{
"label": "assignments",
"anchor": "Assignments"
}
],
[
{
"label": "reference",
"anchor": "Reference"
}
]
]
},
"items": [
{
"kind": "customsearch#result",
"title": "EE364a: Lecture Videos",
"htmlTitle": "EE364a: \u003cb\u003eLecture\u003c/b\u003e Videos",
"link": "http://www.stanford.edu/class/ee364a/videos.html",
"displayLink": "www.stanford.edu",
"snippet": "Apr 7, 2010 ... Course materials. Lecture slides · Lecture videos (2008) · Review sessions. Assignments. Homework · Reading. Exams. Final exam ...",
"htmlSnippet": "Apr 7, 2010 \u003cb\u003e...\u003c/b\u003e Course materials. \u003cb\u003eLecture\u003c/b\u003e slides · \u003cb\u003eLecture\u003c/b\u003e videos (2008) · Review sessions. \u003cbr\u003e Assignments. Homework · Reading. Exams. Final exam \u003cb\u003e...\u003c/b\u003e",
"cacheid": "TxVqFzFZLOsJ"
}
]
}
);
C# Snippet
public class GoogleSearchResults
{
public string link { get; set; }
}
public class Program
{
static void Main(string[] args)
{
//input search term
Console.WriteLine("What is your search query?:");
string searchTerm = Console.ReadLine();
//concantenate the strings using + symbol to make it URL friendly for google
string searchTermFormat = searchTerm.Replace(" ", "+");
//create a new instance of Webclient and use DownloadString method from the Webclient class to extract download html
WebClient client = new WebClient();
string Json = client.DownloadString("https://www.googleapis.com/customsearch/v1?key=My Key&cx=My CX&q=" + searchTermFormat);
//create a new instance of JavaScriptSerializer and deserialise the desired content
JavaScriptSerializer js = new JavaScriptSerializer();
GoogleSearchResults results = js.Deserialize<GoogleSearchResults>(Json);
Console.WriteLine(results);
//Console.WriteLine(htmlDoc);
Console.ReadLine();
}
}
Thanks
I use your #2 approach: deserialize with the JavaScriptSerializer.
This is what I do to deserialize a response from Facebook:
// get the id for the uploaded photo
var jss = new JavaScriptSerializer();
var resource = jss.Deserialize<Facebook.Data.Resource>(responseText);
....where Facebook.Data.Resource is defined like this:
namespace Facebook.Data
{
public class Resource
{
public string id { get; set; }
}
}
The responseText that I am deserializing from looks like this:
{"id":"10150111918987952",
"from":{"name":"Someone",
"id":"782272221"},
"name":"uploaded from Cropper. (at 12\/15\/2010 7:06:41 AM)",
"picture":"http:\/\/photos-f.ak.fbcdn.net\/hphotos-ak-snc4\/hs817.snc4\/69790_101501113333332_782377951_7551951_8193638_s.jpg",
...
But since I have only one property defined in the Resource class, I only deserialize that. Define the fields in your class that you want to deserialize.
It works to use inheritance, of course. You can define your data classes like this:
namespace Facebook.Data
{
public class Resource
{
public string id { get; set; }
}
public class Person : Resource
{
public string name { get; set; }
}
}
...and then you can deserialize a Person object.
EDIT
Ok, given the sample json you provided in the updated question, here's how I wrote the classes to hold the response:
public class GoogleSearchItem
{
public string kind { get; set; }
public string title { get; set; }
public string link { get; set; }
public string displayLink { get; set; }
// and so on... add more properties here if you want
// to deserialize them
}
public class SourceUrl
{
public string type { get; set; }
public string template { get; set; }
}
public class GoogleSearchResults
{
public string kind { get; set; }
public SourceUrl url { get; set; }
public GoogleSearchItem[] items { get; set; }
// and so on... add more properties here if you want to
// deserialize them
}
And here's the C# code to deserialize:
// create a new instance of JavaScriptSerializer
JavaScriptSerializer s1 = new JavaScriptSerializer();
// deserialise the received response
GoogleSearchResults results = s1.Deserialize<GoogleSearchResults>(json);
Console.WriteLine(s1.Serialize(results));
Some comments:
The toplevel class to hold the search result is called GoogleSearchResults.
The first property in the GoogleSearchResults class is kind, corresponding to the first named property in the json object. You had link which isn't going to work, because link is not the name of a top-level property in that json object. There are properties lower in the hierarchy of your json named "link" but JavaScriptSerializer won't pull out those lower level things into the higher level.
The next property in my GoogleSearchResults class is of type SourceUrl. This is because the url property in the json is not a simple string - it is a json object with two properties, each with a string value. So SourceUrl as a class in C# gets two string properties, each with the appropriate name to deserialize one of those named properties.
the next property in the GoogleSearchResults class is called "items" so that it can deserialize the items dictionary from your json. Now items, as the name suggests, is an array in the json, as denoted by the square bracket around its value. This means there can be more than one item, although in your case there is just one item. So this property in C# must be an array (or collection). Each item in the json result is not a simple string, so, once again, as we did with SourceUrl, we need to define a holder class to deserialize the item object: GoogleSearchItem. This class has a bunch of simple string properties. The properties in the C# class could also be of type int or some other type, if that's what the json requires.
finally, when printing out the result, if you just call Console.WriteLine(result) you will see the result of the ToString() method that is implicitly invoked by Console.WriteLine. This will merely print the name of the type, in this case is "GoogleSearchResults", which is not what you want, I think. In order to see what's in the object, you need to serialize it, as I've shown. In the output of that, you will see only the values of things you deserialized. Using the classes I provided, the result will have less information than the original, because I didn't provide properties in the C# class corresponding to some of the json properties, so those weren't deserialized.
You could take a look at Json.NET and its LINQ support to create and query JSON. By crafting a nice LINQ query you will get only the stuff you need (you can select, group by, count, min, max, whatever you like).
http://msdn.microsoft.com/en-us/library/bb412170.aspx
http://msdn.microsoft.com/en-us/library/bb410770.aspx
Pull out the property you need after you have converted the JSON representation to a type in your C# app. I don't think there's a way to extract only one property from the JSON representation before you have converted it (though I am not sure).