How to Deserialize JSON data

Question

I am new to working with JSON data   I am reading data from a web service  The query data sent back is the following      B02001 001E   NAME   state       4712651   Alabama   01       691189   Alaska   02       6246816   Arizona   04       18511620   Florida   12       9468815   Georgia   13       1333591   Hawaii   15       1526797   Idaho   16       3762322   Puerto Rico   72      Is there a way to Deserialize this data in such a way that the base object will be generated without me first defining what the object is like  In the above example the object is defined by the first row                B02001 001E   NAME   state      In general the web service will return the query data formatted as a two dimensional JSON array where the first row provides column names and subsequent rows provide data values

User · Answer

If you use  Net 4 5 you can also use standard  Net json serializer   using System Runtime Serialization Json          Stream jsonSource           serializer will read data stream var s   new DataContractJsonSerializer typeof string        var j    string     s ReadObject jsonSource     In  Net 4 5 and older you can use JavaScriptSerializer class   using System Web Script Serialization      JavaScriptSerializer serializer   new JavaScriptSerializer    string     list   serializer Deserialize lt string     gt  json

User · Answer

You can write your own JSON parser and make it more generic based on your requirement  Here is one which served my purpose nicely  hope will help you too   class JsonParsor       public static DataTable JsonParse String rawJson                DataTable dataTable   new DataTable            Dictionary lt string  string gt  outdict   new Dictionary lt string  string gt             StringBuilder keybufferbuilder   new StringBuilder            StringBuilder valuebufferbuilder   new StringBuilder            StringReader bufferreader   new StringReader rawJson           int s   0          bool reading   false          bool inside string   false          bool reading value   false          bool reading number   false          while  s  gt   0                        s   bufferreader Read                  open JSON             if   reading                                if   char s         amp  amp   inside string  amp  amp   reading                                        reading   true                      continue                                    if   char s         amp  amp   inside string  amp  amp   reading                      break                  if   char s         amp  amp   inside string  amp  amp   reading                      continue                  if   char s                             continue                            else                               if  reading value                                        if   inside string  amp  amp   char s  gt    0   amp  amp   char s  lt    9                                                 reading number   true                          valuebufferbuilder Append  char s                           continue                                                            if we find a quote and we are not yet inside a string  advance and get inside                 if   inside string                                        if   char s          amp  amp   inside string                          inside string   true                      if   char s         amp  amp   inside string                                                keybufferbuilder Length   0                          valuebufferbuilder Length   0                                  reading   false                                  inside string   false                                  reading value   false                                            if   char s         amp  amp   inside string  amp  amp  reading number                                                if   dataTable Columns Contains keybufferbuilder ToString                                 dataTable Columns Add keybufferbuilder ToString    typeof string                            if   outdict ContainsKey keybufferbuilder ToString                                 outdict Add keybufferbuilder ToString    valuebufferbuilder ToString                             keybufferbuilder Length   0                          valuebufferbuilder Length   0                          reading value   false                          reading number   false                                            continue                                       if we reach end of the string                 if  inside string                                        if   char s                                                        inside string   false                          s   bufferreader Read                            if   char s                                                               reading value   true                              continue                                                    if  reading value  amp  amp   char s                                                                 put the key-value pair into dictionary                             if  dataTable Columns Contains keybufferbuilder ToString                                     dataTable Columns Add keybufferbuilder ToString   typeof string                                if   outdict ContainsKey keybufferbuilder ToString                                 outdict Add keybufferbuilder ToString    valuebufferbuilder ToString                                 keybufferbuilder Length   0                              valuebufferbuilder Length   0                              reading value   false                                                    if  reading value  amp  amp   char s                                                               if   dataTable Columns Contains keybufferbuilder ToString                                     dataTable Columns Add keybufferbuilder ToString    typeof string                                if   outdict ContainsKey keybufferbuilder ToString                                     outdict Add keybufferbuilder ToString    valuebufferbuilder ToString                                 ICollection key   outdict Keys                              DataRow newrow   dataTable NewRow                                foreach  string k loopVariable in key                                                                CommonModule LogTheMessage outdict k loopVariable                                             newrow k loopVariable    outdict k loopVariable                                                             dataTable Rows Add newrow                               CommonModule LogTheMessage dataTable Rows Count ToString         row count                                    outdict Clear                                keybufferbuilder Length 0                              valuebufferbuilder Length 0                              reading value   false                              reading   false                              continue                                                                      else                                               if  reading value                                                        valuebufferbuilder Append  char s                               continue                                                    else                                                       keybufferbuilder Append  char s                               continue                                                                                    else                                       switch   char s                                                case                                  reading value   true                              break                          default                              if  reading value                                                                valuebufferbuilder Append  char s                                                             else                                                               keybufferbuilder Append  char s                                                             break                                                                           return dataTable

User · Answer

Step 1  Go to json org to find the JSON library for whatever technology you re using to call this web service  Download and link to that library   Step 2  Let s say you re using Java  You would use JSONArray like this   JSONArray myArray new JSONArray queryResponse   for  int i 0 i lt myArray length i         JSONArray myInteriorArray myArray getJSONArray i       if  i  0              this is the first one and is special because it holds the name of the query       else            do your stuff         String stateCode myInteriorArray getString 0           String stateName myInteriorArray getString 1

User · Answer

You can deserialize this really easily  The data s structure in C  is just List lt string   gt  so you could just do     List lt string   gt  data   JsonConvert DeserializeObject lt List lt string   gt  gt  jsonString     The above code is assuming you re using json NET   EDIT  Note the json is technically an array of string arrays  I prefer to use List lt string   gt  for my own declaration because it s imo more intuitive  It won t cause any problems for json NET  if you want it to be an array of string arrays then you need to change the type to  I think  string     but there are some funny little gotcha s with jagged and 2D arrays in C  that I don t really know about so I just don t bother dealing with it here

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