Serialize Class containing Dictionary member

Question

Expanding upon my earlier problem  I ve decided to  de serialize my config file class which worked great    I now want to store an associative array of drive letters to map  key is the drive letter  value is the network path  and have tried using Dictionary  HybridDictionary  and Hashtable for this but I always get the following error when calling ConfigFile Load   or ConfigFile Save        There was an error reflecting type    App ConfigFile    snip    System NotSupportedException  Cannot   serialize member   App Configfile mappedDrives  snip    From what I ve read Dictionaries and HashTables can be serialized  so what am I doing wrong    XmlRoot ElementName  Config    public class ConfigFile       public String guiPath   get  set        public string configPath   get  set        public Dictionary lt string  string gt  mappedDrives   new Dictionary lt string  string gt          public Boolean Save String filename                using var filestream   File Open filename  FileMode OpenOrCreate FileAccess ReadWrite                         try                               var serializer   new XmlSerializer typeof ConfigFile                    serializer Serialize filestream  this                   return true                catch Exception e                    MessageBox Show e Message                   return false                                     public void addDrive string drvLetter  string path                this mappedDrives Add drvLetter  path              public static ConfigFile Load string filename                using  var filestream   File Open filename  FileMode Open  FileAccess Read                         try                               var serializer   new XmlSerializer typeof ConfigFile                    return  ConfigFile serializer Deserialize filestream                             catch  Exception ex                                MessageBox Show ex Message   ex ToString                     return new ConfigFile

User · Accepted Answer

You can t serialize a class that implements IDictionary  Check out this link      Q  Why can t I serialize hashtables       A  The XmlSerializer cannot process   classes implementing the IDictionary   interface  This was partly due to   schedule constraints and partly due to   the fact that a hashtable does not   have a counterpart in the XSD type   system  The only solution is to   implement a custom hashtable that does   not implement the IDictionary   interface    So I think you need to create your own version of the Dictionary for this  Check this other question

User · Answer

I wanted a SerializableDictionary class that used xml attributes for key value so I ve adapted Paul Welter s class   This produces xml like    lt Dictionary gt     lt Item Key  Grass  Value  Green    gt     lt Item Key  Snow  Value  White    gt     lt Item Key  Sky  Value  Blue    gt   lt  Dictionary gt     Code   using System Collections Generic  using System Xml  using System Xml Linq  using System Xml Serialization   namespace DataTypes        XmlRoot  Dictionary        public class SerializableDictionary lt TKey  TValue gt            Dictionary lt TKey  TValue gt   IXmlSerializable            region IXmlSerializable Members         public System Xml Schema XmlSchema GetSchema                 return null                     public void ReadXml XmlReader reader                XDocument doc   null              using  XmlReader subtreeReader   reader ReadSubtree                      doc   XDocument Load subtreeReader                             XmlSerializer serializer   new XmlSerializer typeof SerializableKeyValuePair lt TKey  TValue gt                 foreach  XElement item in doc Descendants XName Get  Item                       using XmlReader itemReader    item CreateReader                          var kvp   serializer Deserialize itemReader  as SerializableKeyValuePair lt TKey  TValue gt                       this Add kvp Key  kvp Value                                               reader ReadEndElement                       public void WriteXml System Xml XmlWriter writer                XmlSerializer serializer   new XmlSerializer typeof SerializableKeyValuePair lt TKey  TValue gt                 XmlSerializerNamespaces ns   new XmlSerializerNamespaces                ns Add                      foreach  TKey key in this Keys                    TValue value   this key                   var kvp   new SerializableKeyValuePair lt TKey  TValue gt  key  value                   serializer Serialize writer  kvp  ns                                    endregion           XmlRoot  Item            public class SerializableKeyValuePair lt TKey  TValue gt                 XmlAttribute  Key                public TKey Key                XmlAttribute  Value                public TValue Value                    lt summary gt                  Default constructor                  lt  summary gt              public SerializableKeyValuePair               public SerializableKeyValuePair  TKey key  TValue value                Key   key              Value   value                        Unit Tests   using System IO  using System Linq  using System Xml  using System Xml Linq  using Microsoft VisualStudio TestTools UnitTesting   namespace DataTypes        TestClass      public class SerializableDictionaryTests            TestMethod          public void TestStringStringDict                 var dict   new SerializableDictionary lt string  string gt                 dict Add  Grass    Green                dict Add  Snow    White                dict Add  Sky    Blue                dict Add  Tomato    Red                dict Add  Coal    Black                dict Add  Mud    Brown                 var serializer   new System Xml Serialization XmlSerializer dict GetType                 using  var stream   new MemoryStream                         Load memory stream with this objects xml representation                 XmlWriter xmlWriter   null                  try                       xmlWriter   XmlWriter Create stream                       serializer Serialize xmlWriter  dict                     finally                       xmlWriter Close                                          Rewind                 stream Seek 0  SeekOrigin Begin                    XDocument doc   XDocument Load stream                   Assert AreEqual  Dictionary   doc Root Name                   Assert AreEqual dict Count  doc Root Descendants   Count                         Rewind                 stream Seek 0  SeekOrigin Begin                   var outDict   serializer Deserialize stream  as SerializableDictionary lt string  string gt                   Assert AreEqual dict  Grass    outDict  Grass                     Assert AreEqual dict  Snow    outDict  Snow                     Assert AreEqual dict  Sky    outDict  Sky                                       TestMethod          public void TestIntIntDict                 var dict   new SerializableDictionary lt int  int gt                 dict Add 4  7               dict Add 5  9               dict Add 7  8                var serializer   new System Xml Serialization XmlSerializer dict GetType                 using  var stream   new MemoryStream                         Load memory stream with this objects xml representation                 XmlWriter xmlWriter   null                  try                       xmlWriter   XmlWriter Create stream                       serializer Serialize xmlWriter  dict                     finally                       xmlWriter Close                                          Rewind                 stream Seek 0  SeekOrigin Begin                    XDocument doc   XDocument Load stream                   Assert AreEqual  Dictionary   doc Root Name                   Assert AreEqual 3  doc Root Descendants   Count                         Rewind                 stream Seek 0  SeekOrigin Begin                   var outDict   serializer Deserialize stream  as SerializableDictionary lt int  int gt                   Assert AreEqual dict 4   outDict 4                    Assert AreEqual dict 5   outDict 5                    Assert AreEqual dict 7   outDict 7

User · Answer

I wanted a SerializableDictionary class that used xml attributes for key value so I ve adapted Paul Welter s class   This produces xml like    lt Dictionary gt     lt Item Key  Grass  Value  Green    gt     lt Item Key  Snow  Value  White    gt     lt Item Key  Sky  Value  Blue    gt   lt  Dictionary gt     Code   using System Collections Generic  using System Xml  using System Xml Linq  using System Xml Serialization   namespace DataTypes        XmlRoot  Dictionary        public class SerializableDictionary lt TKey  TValue gt            Dictionary lt TKey  TValue gt   IXmlSerializable            region IXmlSerializable Members         public System Xml Schema XmlSchema GetSchema                 return null                     public void ReadXml XmlReader reader                XDocument doc   null              using  XmlReader subtreeReader   reader ReadSubtree                      doc   XDocument Load subtreeReader                             XmlSerializer serializer   new XmlSerializer typeof SerializableKeyValuePair lt TKey  TValue gt                 foreach  XElement item in doc Descendants XName Get  Item                       using XmlReader itemReader    item CreateReader                          var kvp   serializer Deserialize itemReader  as SerializableKeyValuePair lt TKey  TValue gt                       this Add kvp Key  kvp Value                                               reader ReadEndElement                       public void WriteXml System Xml XmlWriter writer                XmlSerializer serializer   new XmlSerializer typeof SerializableKeyValuePair lt TKey  TValue gt                 XmlSerializerNamespaces ns   new XmlSerializerNamespaces                ns Add                      foreach  TKey key in this Keys                    TValue value   this key                   var kvp   new SerializableKeyValuePair lt TKey  TValue gt  key  value                   serializer Serialize writer  kvp  ns                                    endregion           XmlRoot  Item            public class SerializableKeyValuePair lt TKey  TValue gt                 XmlAttribute  Key                public TKey Key                XmlAttribute  Value                public TValue Value                    lt summary gt                  Default constructor                  lt  summary gt              public SerializableKeyValuePair               public SerializableKeyValuePair  TKey key  TValue value                Key   key              Value   value                        Unit Tests   using System IO  using System Linq  using System Xml  using System Xml Linq  using Microsoft VisualStudio TestTools UnitTesting   namespace DataTypes        TestClass      public class SerializableDictionaryTests            TestMethod          public void TestStringStringDict                 var dict   new SerializableDictionary lt string  string gt                 dict Add  Grass    Green                dict Add  Snow    White                dict Add  Sky    Blue                dict Add  Tomato    Red                dict Add  Coal    Black                dict Add  Mud    Brown                 var serializer   new System Xml Serialization XmlSerializer dict GetType                 using  var stream   new MemoryStream                         Load memory stream with this objects xml representation                 XmlWriter xmlWriter   null                  try                       xmlWriter   XmlWriter Create stream                       serializer Serialize xmlWriter  dict                     finally                       xmlWriter Close                                          Rewind                 stream Seek 0  SeekOrigin Begin                    XDocument doc   XDocument Load stream                   Assert AreEqual  Dictionary   doc Root Name                   Assert AreEqual dict Count  doc Root Descendants   Count                         Rewind                 stream Seek 0  SeekOrigin Begin                   var outDict   serializer Deserialize stream  as SerializableDictionary lt string  string gt                   Assert AreEqual dict  Grass    outDict  Grass                     Assert AreEqual dict  Snow    outDict  Snow                     Assert AreEqual dict  Sky    outDict  Sky                                       TestMethod          public void TestIntIntDict                 var dict   new SerializableDictionary lt int  int gt                 dict Add 4  7               dict Add 5  9               dict Add 7  8                var serializer   new System Xml Serialization XmlSerializer dict GetType                 using  var stream   new MemoryStream                         Load memory stream with this objects xml representation                 XmlWriter xmlWriter   null                  try                       xmlWriter   XmlWriter Create stream                       serializer Serialize xmlWriter  dict                     finally                       xmlWriter Close                                          Rewind                 stream Seek 0  SeekOrigin Begin                    XDocument doc   XDocument Load stream                   Assert AreEqual  Dictionary   doc Root Name                   Assert AreEqual 3  doc Root Descendants   Count                         Rewind                 stream Seek 0  SeekOrigin Begin                   var outDict   serializer Deserialize stream  as SerializableDictionary lt int  int gt                   Assert AreEqual dict 4   outDict 4                    Assert AreEqual dict 5   outDict 5                    Assert AreEqual dict 7   outDict 7

User · Answer

the Dictionary class implements ISerializable  The definition of Class Dictionary given below    DebuggerTypeProxy typeof Mscorlib DictionaryDebugView lt   gt      DebuggerDisplay  Count    Count      Serializable   System Runtime InteropServices ComVisible false   public class Dictionary lt TKey TValue gt   IDictionary lt TKey TValue gt   IDictionary  IReadOnlyDictionary lt TKey  TValue gt   ISerializable  IDeserializationCallback     I don t think that is the problem  refer to the below link  which says that if you are having any other data type which is not serializable then Dictionary will not be serialized  http   forums asp net t 1734187 aspx Is Dictionary serializable

User · Answer

This article explains exactly how to handle this  How do I    Serialize a hash table in C  when the application requires it   I hope this is helpful

User · Answer

Dictionaries and Hashtables are not serializable with XmlSerializer  Therefore you cannot use them directly  A workaround would be to use the XmlIgnore attribute to hide those properties from the serializer and expose them via a list of serializable key-value pairs   PS  constructing an XmlSerializer is very expensive  so always cache it if there is a chance of being able to re-use it

User · Answer

You can use ExtendedXmlSerializer   If you have a class   public class ConfigFile       public String guiPath   get  set        public string configPath   get  set        public Dictionary lt string  string gt  mappedDrives  get set         public ConfigFile                 mappedDrives   new Dictionary lt string  string gt               and create instance of this class   ConfigFile config   new ConfigFile    config guiPath    guiPath   config configPath    configPath   config mappedDrives Add  Mouse    Logitech MX Master    config mappedDrives Add  keyboard    Microsoft Natural Ergonomic Keyboard 4000      You can serialize this object using ExtendedXmlSerializer   ExtendedXmlSerializer serializer   new ExtendedXmlSerializer    var xml   serializer Serialize config     Output xml will look like    lt  xml version  1 0  encoding  utf-8   gt   lt ConfigFile type  Program ConfigFile  gt       lt guiPath gt guiPath lt  guiPath gt       lt configPath gt configPath lt  configPath gt       lt mappedDrives gt           lt Item gt               lt Key gt Mouse lt  Key gt               lt Value gt Logitech MX Master lt  Value gt           lt  Item gt           lt Item gt               lt Key gt keyboard lt  Key gt               lt Value gt Microsoft Natural Ergonomic Keyboard 4000 lt  Value gt           lt  Item gt       lt  mappedDrives gt   lt  ConfigFile gt    You can install ExtendedXmlSerializer from nuget or run the following command   Install-Package ExtendedXmlSerializer   Here is online example

User · Answer

There is a solution at Paul Welter s Weblog - XML Serializable Generic Dictionary      For some reason  the generic Dictionary in  net 2 0 is not XML serializable   The following code snippet is a xml serializable generic dictionary   The dictionary is serialzable by implementing the IXmlSerializable interface     using System  using System Collections Generic  using System Text  using System Xml Serialization    XmlRoot  dictionary    public class SerializableDictionary lt TKey  TValue gt        Dictionary lt TKey  TValue gt   IXmlSerializable       public SerializableDictionary           public SerializableDictionary IDictionary lt TKey  TValue gt  dictionary    base dictionary          public SerializableDictionary IDictionary lt TKey  TValue gt  dictionary  IEqualityComparer lt TKey gt  comparer    base dictionary  comparer          public SerializableDictionary IEqualityComparer lt TKey gt  comparer    base comparer          public SerializableDictionary int capacity    base capacity          public SerializableDictionary int capacity  IEqualityComparer lt TKey gt  comparer    base capacity  comparer            region IXmlSerializable Members     public System Xml Schema XmlSchema GetSchema                 return null             public void ReadXml System Xml XmlReader reader                XmlSerializer keySerializer   new XmlSerializer typeof TKey            XmlSerializer valueSerializer   new XmlSerializer typeof TValue             bool wasEmpty   reader IsEmptyElement          reader Read             if  wasEmpty              return           while  reader NodeType    System Xml XmlNodeType EndElement                        reader ReadStartElement  item                 reader ReadStartElement  key                TKey key    TKey keySerializer Deserialize reader               reader ReadEndElement                 reader ReadStartElement  value                TValue value    TValue valueSerializer Deserialize reader               reader ReadEndElement                 this Add key  value                reader ReadEndElement                reader MoveToContent                      reader ReadEndElement               public void WriteXml System Xml XmlWriter writer                XmlSerializer keySerializer   new XmlSerializer typeof TKey            XmlSerializer valueSerializer   new XmlSerializer typeof TValue             foreach  TKey key in this Keys                        writer WriteStartElement  item                 writer WriteStartElement  key                keySerializer Serialize writer  key               writer WriteEndElement                 writer WriteStartElement  value                TValue value   this key               valueSerializer Serialize writer  value               writer WriteEndElement                 writer WriteEndElement                         endregion

User · Answer

There is a solution at Paul Welter s Weblog - XML Serializable Generic Dictionary      For some reason  the generic Dictionary in  net 2 0 is not XML serializable   The following code snippet is a xml serializable generic dictionary   The dictionary is serialzable by implementing the IXmlSerializable interface     using System  using System Collections Generic  using System Text  using System Xml Serialization    XmlRoot  dictionary    public class SerializableDictionary lt TKey  TValue gt        Dictionary lt TKey  TValue gt   IXmlSerializable       public SerializableDictionary           public SerializableDictionary IDictionary lt TKey  TValue gt  dictionary    base dictionary          public SerializableDictionary IDictionary lt TKey  TValue gt  dictionary  IEqualityComparer lt TKey gt  comparer    base dictionary  comparer          public SerializableDictionary IEqualityComparer lt TKey gt  comparer    base comparer          public SerializableDictionary int capacity    base capacity          public SerializableDictionary int capacity  IEqualityComparer lt TKey gt  comparer    base capacity  comparer            region IXmlSerializable Members     public System Xml Schema XmlSchema GetSchema                 return null             public void ReadXml System Xml XmlReader reader                XmlSerializer keySerializer   new XmlSerializer typeof TKey            XmlSerializer valueSerializer   new XmlSerializer typeof TValue             bool wasEmpty   reader IsEmptyElement          reader Read             if  wasEmpty              return           while  reader NodeType    System Xml XmlNodeType EndElement                        reader ReadStartElement  item                 reader ReadStartElement  key                TKey key    TKey keySerializer Deserialize reader               reader ReadEndElement                 reader ReadStartElement  value                TValue value    TValue valueSerializer Deserialize reader               reader ReadEndElement                 this Add key  value                reader ReadEndElement                reader MoveToContent                      reader ReadEndElement               public void WriteXml System Xml XmlWriter writer                XmlSerializer keySerializer   new XmlSerializer typeof TKey            XmlSerializer valueSerializer   new XmlSerializer typeof TValue             foreach  TKey key in this Keys                        writer WriteStartElement  item                 writer WriteStartElement  key                keySerializer Serialize writer  key               writer WriteEndElement                 writer WriteStartElement  value                TValue value   this key               valueSerializer Serialize writer  value               writer WriteEndElement                 writer WriteEndElement                         endregion

User · Answer

You should explore Json Net  quite easy to use and allows Json objects to be deserialized in Dictionary directly   james newtonking  example   string json        key1     value1     key2     value2      Dictionary lt string  string gt  values   JsonConvert DeserializeObject lt Dictionary lt string  string gt  gt  json    Console WriteLine values Count      2 Console WriteLine values  key1        value1

User · Answer

You can use ExtendedXmlSerializer   If you have a class   public class ConfigFile       public String guiPath   get  set        public string configPath   get  set        public Dictionary lt string  string gt  mappedDrives  get set         public ConfigFile                 mappedDrives   new Dictionary lt string  string gt               and create instance of this class   ConfigFile config   new ConfigFile    config guiPath    guiPath   config configPath    configPath   config mappedDrives Add  Mouse    Logitech MX Master    config mappedDrives Add  keyboard    Microsoft Natural Ergonomic Keyboard 4000      You can serialize this object using ExtendedXmlSerializer   ExtendedXmlSerializer serializer   new ExtendedXmlSerializer    var xml   serializer Serialize config     Output xml will look like    lt  xml version  1 0  encoding  utf-8   gt   lt ConfigFile type  Program ConfigFile  gt       lt guiPath gt guiPath lt  guiPath gt       lt configPath gt configPath lt  configPath gt       lt mappedDrives gt           lt Item gt               lt Key gt Mouse lt  Key gt               lt Value gt Logitech MX Master lt  Value gt           lt  Item gt           lt Item gt               lt Key gt keyboard lt  Key gt               lt Value gt Microsoft Natural Ergonomic Keyboard 4000 lt  Value gt           lt  Item gt       lt  mappedDrives gt   lt  ConfigFile gt    You can install ExtendedXmlSerializer from nuget or run the following command   Install-Package ExtendedXmlSerializer   Here is online example

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the Dictionary class implements ISerializable  The definition of Class Dictionary given below    DebuggerTypeProxy typeof Mscorlib DictionaryDebugView lt   gt      DebuggerDisplay  Count    Count      Serializable   System Runtime InteropServices ComVisible false   public class Dictionary lt TKey TValue gt   IDictionary lt TKey TValue gt   IDictionary  IReadOnlyDictionary lt TKey  TValue gt   ISerializable  IDeserializationCallback     I don t think that is the problem  refer to the below link  which says that if you are having any other data type which is not serializable then Dictionary will not be serialized  http   forums asp net t 1734187 aspx Is Dictionary serializable

User · Answer

You should explore Json Net  quite easy to use and allows Json objects to be deserialized in Dictionary directly   james newtonking  example   string json        key1     value1     key2     value2      Dictionary lt string  string gt  values   JsonConvert DeserializeObject lt Dictionary lt string  string gt  gt  json    Console WriteLine values Count      2 Console WriteLine values  key1        value1

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Create a serialization surrogate   Example  you have a class with public property of type Dictionary   To support Xml serialization of this type  create a generic key-value class   public class SerializeableKeyValue lt T1 T2 gt        public T1 Key   get  set        public T2 Value   get  set        Add an XmlIgnore attribute to your original property        XmlIgnore      public Dictionary lt int  string gt  SearchCategories   get  set      Expose a public property of array type  that holds an array of SerializableKeyValue instances  which are used to serialize and deserialize into the SearchCategories property       public SerializeableKeyValue lt int  string gt    SearchCategoriesSerializable               get                       var list   new List lt SerializeableKeyValue lt int  string gt  gt                 if  SearchCategories    null                                list AddRange SearchCategories Keys Select key   gt  new SerializeableKeyValue lt int  string gt     Key   key  Value   SearchCategories key                                return list ToArray                      set                       SearchCategories   new Dictionary lt int  string gt                 foreach  var item in value                                SearchCategories Add  item Key  item Value

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Instead of using XmlSerializer you can use a System Runtime Serialization DataContractSerializer  This can serialize dictionaries and interfaces no sweat   Here is a link to a full example  http   theburningmonk com 2010 05 net-tips-xml-serialize-or-deserialize-dictionary-in-csharp

User · Answer

Dictionaries and Hashtables are not serializable with XmlSerializer  Therefore you cannot use them directly  A workaround would be to use the XmlIgnore attribute to hide those properties from the serializer and expose them via a list of serializable key-value pairs   PS  constructing an XmlSerializer is very expensive  so always cache it if there is a chance of being able to re-use it

User · Answer

Instead of using XmlSerializer you can use a System Runtime Serialization DataContractSerializer  This can serialize dictionaries and interfaces no sweat   Here is a link to a full example  http   theburningmonk com 2010 05 net-tips-xml-serialize-or-deserialize-dictionary-in-csharp

User · Answer

Dictionaries and Hashtables are not serializable with XmlSerializer  Therefore you cannot use them directly  A workaround would be to use the XmlIgnore attribute to hide those properties from the serializer and expose them via a list of serializable key-value pairs   PS  constructing an XmlSerializer is very expensive  so always cache it if there is a chance of being able to re-use it

User · Answer

Create a serialization surrogate   Example  you have a class with public property of type Dictionary   To support Xml serialization of this type  create a generic key-value class   public class SerializeableKeyValue lt T1 T2 gt        public T1 Key   get  set        public T2 Value   get  set        Add an XmlIgnore attribute to your original property        XmlIgnore      public Dictionary lt int  string gt  SearchCategories   get  set      Expose a public property of array type  that holds an array of SerializableKeyValue instances  which are used to serialize and deserialize into the SearchCategories property       public SerializeableKeyValue lt int  string gt    SearchCategoriesSerializable               get                       var list   new List lt SerializeableKeyValue lt int  string gt  gt                 if  SearchCategories    null                                list AddRange SearchCategories Keys Select key   gt  new SerializeableKeyValue lt int  string gt     Key   key  Value   SearchCategories key                                return list ToArray                      set                       SearchCategories   new Dictionary lt int  string gt                 foreach  var item in value                                SearchCategories Add  item Key  item Value

User · Answer

Dictionaries and Hashtables are not serializable with XmlSerializer  Therefore you cannot use them directly  A workaround would be to use the XmlIgnore attribute to hide those properties from the serializer and expose them via a list of serializable key-value pairs   PS  constructing an XmlSerializer is very expensive  so always cache it if there is a chance of being able to re-use it

User · Answer

This article explains exactly how to handle this  How do I    Serialize a hash table in C  when the application requires it   I hope this is helpful

[c#] Serialize Class containing Dictionary member

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