Xamarin.Forms.Pages/JsonDataSource.cs

   1 using System;
   2 using System.Collections.Generic;
   3 using System.Collections.ObjectModel;
   4 using System.Linq;
   5 using System.Threading.Tasks;
   6 using Newtonsoft.Json.Linq;
   7
   8 namespace Xamarin.Forms.Pages
   9 {
  10         public class JsonDataSource : BaseDataSource
  11         {
  12                 readonly ObservableCollection<IDataItem> _dataItems = new ObservableCollection<IDataItem>();
  13                 Task _currentParseTask;
  14                 bool _initialized;
  15                 JsonSource _source;
  16
  17                 public JsonDataSource()
  18                 {
  19                 }
  20
  21                 internal JsonDataSource(JToken rootToken)
  22                 {
  23                         ParseJsonToken(rootToken);
  24                 }
  25
  26                 [TypeConverter(typeof(JsonSourceConverter))]
  27                 public JsonSource Source
  28                 {
  29                         get { return _source; }
  30                         set
  31                         {
  32                                 if (_source == value)
  33                                         return;
  34                                 _source = value;
  35
  36                                 _dataItems.Clear();
  37                                 if (value != null && _initialized)
  38                                 {
  39                                         _currentParseTask = ParseJson();
  40                                         _currentParseTask.ContinueWith(t => { throw t.Exception; }, TaskContinuationOptions.OnlyOnFaulted);
  41                                 }
  42                         }
  43                 }
  44
  45                 protected override async Task<IList<IDataItem>> GetRawData()
  46                 {
  47                         if (!_initialized)
  48                         {
  49                                 Task task = _currentParseTask = ParseJson();
  50                                 await task;
  51                         }
  52                         else if (_currentParseTask != null && _currentParseTask.IsCompleted == false)
  53                                 await _currentParseTask;
  54                         return _dataItems;
  55                 }
  56
  57                 protected override object GetValue(string key)
  58                 {
  59                         IDataItem target = _dataItems.FirstOrDefault(d => d.Name == key);
  60                         return target?.Value;
  61                 }
  62
  63                 protected override bool SetValue(string key, object value)
  64                 {
  65                         IDataItem target = _dataItems.FirstOrDefault(d => d.Name == key);
  66                         if (target == null)
  67                         {
  68                                 _dataItems.Add(new DataItem(key, value));
  69                                 return true;
  70                         }
  71                         if (target.Value == value)
  72                                 return false;
  73                         target.Value = value;
  74                         return true;
  75                 }
  76
  77                 object GetValueForJToken(JToken token)
  78                 {
  79                         switch (token.Type)
  80                         {
  81                                 case JTokenType.Object:
  82                                 case JTokenType.Array:
  83                                         return new JsonDataSource(token);
  84                                 case JTokenType.Constructor:
  85                                 case JTokenType.Property:
  86                                 case JTokenType.Comment:
  87                                         throw new NotImplementedException();
  88                                 case JTokenType.Integer:
  89                                         return (int)token;
  90                                 case JTokenType.Float:
  91                                         return (float)token;
  92                                 case JTokenType.Raw:
  93                                 case JTokenType.String:
  94                                         return (string)token;
  95                                 case JTokenType.Boolean:
  96                                         return (bool)token;
  97                                 case JTokenType.Date:
  98                                         return (DateTime)token;
  99                                 case JTokenType.Bytes:
 100                                         return (byte[])token;
 101                                 case JTokenType.Guid:
 102                                         return (Guid)token;
 103                                 case JTokenType.Uri:
 104                                         return (Uri)token;
 105                                 case JTokenType.TimeSpan:
 106                                         return (TimeSpan)token;
 107                                 default:
 108                                         return null;
 109                         }
 110                 }
 111
 112                 async Task ParseJson()
 113                 {
 114                         _initialized = true;
 115
 116                         if (Source == null)
 117                                 return;
 118
 119                         IsLoading = true;
 120                         string json = await Source.GetJson();
 121                         JToken jToken = JToken.Parse(json);
 122                         ParseJsonToken(jToken);
 123                         IsLoading = false;
 124                 }
 125
 126                 void ParseJsonToken(JToken token)
 127                 {
 128                         var jArray = token as JArray;
 129                         var jObject = token as JObject;
 130                         if (jArray != null)
 131                         {
 132                                 for (var i = 0; i < jArray.Count; i++)
 133                                 {
 134                                         JToken obj = jArray[i];
 135                                         _dataItems.Add(new DataItem(i.ToString(), GetValueForJToken(obj)));
 136                                 }
 137                         }
 138                         else if (jObject != null)
 139                         {
 140                                 foreach (KeyValuePair<string, JToken> kvp in jObject)
 141                                 {
 142                                         _dataItems.Add(new DataItem(kvp.Key, GetValueForJToken(kvp.Value)));
 143                                 }
 144                         }
 145                 }
 146         }
 147 }