Serializing a list to JSON

Question

I have an object model that looks like this  public MyObjectInJson      public long ObjectID  get set      public string ObjectInJson  get set      The property ObjectInJson is an already serialized version an object that contains nested lists  For the moment  I m serializing the list of MyObjectInJson manually like this  StringBuilder TheListBuilder   new StringBuilder     TheListBuilder Append  quot   quot    int TheCounter   0   foreach  MyObjectInJson TheObject in TheList      TheCounter      TheListBuilder Append TheObject ObjectInJson      if  TheCounter    TheList Count            TheListBuilder Append  quot   quot          TheListBuilder Append  quot   quot     return TheListBuilder ToString     I wonder if I can replace this sort of dangerous code with JavascriptSerializer and get the same results  How would I do this

User · Accepted Answer

If using  Net Core 3 0 or later   Default to using the built in System Text Json parser implementation   e g   using System Text Json   var json   JsonSerializer Serialize aList     alternatively  other  less mainstream options are available like Utf8Json parser and Jil  These may offer superior performance  if you really need it but  you will need to install their respective packages   If stuck using  Net Core 2 2 or earlier   Default to using Newtonsoft JSON Net as your first choice JSON Parser   e g   using Newtonsoft Json   var json   JsonConvert SerializeObject aList     you may need to install the package first   PM gt  Install-Package Newtonsoft Json   For more details see and upvote the answer that is the source of this information   For reference only  this was the original answer  many years ago      you need to reference System Web Extensions  using System Web Script Serialization   var jsonSerialiser   new JavaScriptSerializer    var json   jsonSerialiser Serialize aList

User · Answer

There are two common ways of doing that with built-in JSON serializers    JavaScriptSerializer  var serializer   new JavaScriptSerializer    return serializer Serialize TheList    DataContractJsonSerializer  var serializer   new DataContractJsonSerializer TheList GetType     using  var stream   new MemoryStream          serializer WriteObject stream  TheList       using  var sr   new StreamReader stream                 return sr ReadToEnd              Note  that this option requires definition of a data contract for your class    DataContract  public class MyObjectInJson       DataMember     public long ObjectID  get set       DataMember     public string ObjectInJson  get set

User · Answer

You can also use Json NET  Just download it at http   james newtonking com pages json-net aspx  extract the compressed file and add it as a reference   Then just serialize the list  or whatever object you want  with the following   using Newtonsoft Json   string json   JsonConvert SerializeObject listTop10     Update  you can also add it to your project via the NuGet Package Manager  Tools --  NuGet Package Manager --  Package Manager Console    PM gt  Install-Package Newtonsoft Json   Documentation  Serializing Collections

User · Answer

If you re doing this in the context of a asp Net Core API action  the conversion to Json is done implicitly   HttpGet  public ActionResult Get         return Ok TheList

User · Answer

public static string JSONSerialize lt T gt  T obj                        string retVal   String Empty              using  MemoryStream ms   new MemoryStream                                  DataContractJsonSerializer serializer   new DataContractJsonSerializer obj GetType                     serializer WriteObject ms  obj                   var byteArray   ms ToArray                    retVal   Encoding UTF8 GetString byteArray  0  byteArray Length                             return retVal

User · Answer

NET already supports basic Json serialization through the System Runtime Serialization Json namespace and the DataContractJsonSerializer class since version 3 5  As the name implies  DataContractJsonSerializer takes into account any data annotations you add to your objects to create the final Json output    That can be handy if you already have annotated data classes that you want to serialize Json to a stream  as described in How To  Serialize and Deserialize JSON Data  There are limitations but it s good enough and fast enough if you have basic needs and don t want to add Yet Another Library to your project   The following code serializea a list to the console output stream  As you see it is a bit more verbose than Json NET and not type-safe  ie no generics           var list   new List lt string gt    a    b    c    d             using var output   Console OpenStandardOutput                                                          var writer   new DataContractJsonSerializer typeof  List lt string gt                 writer WriteObject output list               On the other hand  Json NET provides much better control over how you generate Json  This will come in VERY handy when you have to map javascript-friendly names names to  NET classes  format dates to json etc   Another option is  ServiceStack Text  part of the ServicStack     stack  which provides a set of very fast serializers for Json  JSV and CSV

User · Answer

building on an answer from another posting   I ve come up with a more generic way to build out a list  utilizing dynamic retrieval with Json NET version 12 x  using Newtonsoft Json   static class JsonObj            lt summary gt          Deserializes a json file into an object list         Author  Joseph Poirier 2 26 2019          lt  summary gt           lt typeparam name  T  gt  lt  typeparam gt           lt param name  fileName  gt  lt  param gt           lt returns gt  lt  returns gt      public static List lt T gt  DeSerializeObject lt T gt  string fileName                List lt T gt  objectOut   new List lt T gt              if  string IsNullOrEmpty fileName     return objectOut             try                          reading in full file as text             string ss   File ReadAllText fileName                   went with  lt dynamic gt  over  lt T gt  or  lt List lt T gt  gt  to avoid error                   unexpected character at line 1 column 2             var output   JsonConvert DeserializeObject lt dynamic gt  ss                foreach  var Record in output                                foreach  T data in Record                                        objectOut Add data                                                     catch  Exception ex                          Log exception here             Console Write ex Message                      return objectOut            call to process            string fname          Names json       lt - your json file path             for alternate types replace string with custom class below         List lt string gt  jsonFile   JsonObj DeSerializeObject lt string gt  fname       or this call to process            string fname          Names json       lt - your json file path             for alternate types replace string with custom class below         List lt string gt  jsonFile   new List lt string gt             jsonFile AddRange JsonObj DeSerializeObject lt string gt  fname

[c#] Serializing a list to JSON

If using .Net Core 3.0 or later;

If stuck using .Net Core 2.2 or earlier;

For reference only, this was the original answer, many years ago;

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