Hi all, Having trouble designing a Many to One xml class ... Currently accomplishing the requirements in a class with a switch statement, public class MyClass { public string FirstName { get; set; } public string LastName { get; set; } public bool Employee { get; set; } public int Location { get; set; } public string Description { get; set; } public MyClass(int id) { switch (id) { case 1: case 2: case 100: case 200: this.FirstName = "Joe"; this.LastName = "Dee"; this.Employee = true; this.Location = 11; this.Description = "Bla Bla Bla"; break; case 3: case 4: case 50: case 60: case 600: case 700: case 800: this.FirstName = "Jane"; this.LastName = "Doe"; this.Employee = false; this.Location = 11; this.Description = "Bla Bla Bla"; break; } } } I tried using two xml files linked by a unique id <IDS> <ID id="1">UniqueID1</ID> <ID id="2">UniqueID1</ID> <ID id="100">UniqueID1</ID> <ID id="200">UniqueID1</ID> <ID id="3">UniqueID2</ID> <ID id="4">UniqueID2</ID> <ID id="50">UniqueID2</ID> <ID id="60">UniqueID2</ID> <ID id="600">UniqueID2</ID> <ID id="700">UniqueID2</ID> <ID id="800">UniqueID2</ID> </IDS> and <USERS> <USER id="UniqueID1"> <FIRSTNAME>Joe</FIRSTNAME> <LASTNAME>Dee</LASTNAME> <EMPLOYEE>True</EMPLOYEE> <LOCATION>11</LOCATION> <DESCRIPTION>Bla Bla Bla</DESCRIPTION> </USER> <USER id="UniqueID2"> <FIRSTNAME>Jane</FIRSTNAME> <LASTNAME>Doe</LASTNAME> <EMPLOYEE>False</EMPLOYEE> <LOCATION>11</LOCATION> <DESCRIPTION>Bla Bla Bla</DESCRIPTION> </USER> </USERS> Don't really like the two file approach in the first place, I can live with it. However I was unable to pull it all together into a working package. Any guidance would be much appreciated. Thanks

I'm not really sure I understand what you're looking for exactly. You seem to have a data class that maps to the XML structure you have and that seems fine. I would remove any switch logic in the code though as you're mixing data with the class definition and that probably isn't what you want to do. public class MyClass { public string FirstName { get; set; } public string LastName { get; set; } public bool Employee { get; set; } public int Location { get; set; } public string Description { get; set; } } It sounds like the problem you're having is that you have an XML file that links the same "user" to multiple Ids. It is unclear to me what your first XML file is supposed to represent. I assume it is part of a larger XML that you'll have so I would argue you need to split your data type into 2 pieces as well. The first piece is the user data (your second XML) and the second piece is whatever the first XML represents. public class MyClass { public int Id { get; set; } public User User { get; set; } } public classs User { public string Id { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public bool Employee { get; set; } public int Location { get; set; } public string Description { get; set; } } Can this all be in the same XML file? I'm sure it can but without having a better understanding of the relationship it would be hard to model properly. <IDS> <ID id="1">userId1</ID> </IDS> <USERS> <USER id="userId1"> ... </USER> </USERS> It is up to the XML serializer to create the instances of your types based upon the XML. However object identification is beyond what it can do so you'll end up with multiple user objects for the same user. The only workaround that I'm aware of is to either write a custom ISerializable for your ids type that looks up a user in a list of already generated users. Alternatively just let the serializer do its thing and then after it has produced the objects in memory then go through and clean them up by using a dictionary to map user IDs to the 1 User instance you want to use.

C# class with Many to One XML data

Accepted answer

Michael Taylor 51,346 Reputation points

2022-04-08T15:07:46.87+00:00
I'm not really sure I understand what you're looking for exactly. You seem to have a data class that maps to the XML structure you have and that seems fine. I would remove any switch logic in the code though as you're mixing data with the class definition and that probably isn't what you want to do.

public class MyClass { public string FirstName { get; set; } public string LastName { get; set; } public bool Employee { get; set; } public int Location { get; set; } public string Description { get; set; } }

It sounds like the problem you're having is that you have an XML file that links the same "user" to multiple Ids. It is unclear to me what your first XML file is supposed to represent. I assume it is part of a larger XML that you'll have so I would argue you need to split your data type into 2 pieces as well. The first piece is the user data (your second XML) and the second piece is whatever the first XML represents.

public class MyClass { public int Id { get; set; } public User User { get; set; } } public classs User { public string Id { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public bool Employee { get; set; } public int Location { get; set; } public string Description { get; set; } }

Can this all be in the same XML file? I'm sure it can but without having a better understanding of the relationship it would be hard to model properly.

<IDS> <ID id="1">userId1</ID> </IDS> <USERS> <USER id="userId1"> ... </USER> </USERS>

It is up to the XML serializer to create the instances of your types based upon the XML. However object identification is beyond what it can do so you'll end up with multiple user objects for the same user. The only workaround that I'm aware of is to either write a custom ISerializable for your ids type that looks up a user in a list of already generated users. Alternatively just let the serializer do its thing and then after it has produced the objects in memory then go through and clean them up by using a dictionary to map user IDs to the 1 User instance you want to use.
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Csick 21 Reputation points

2022-04-08T15:43:23.453+00:00

I need to replicate exactly how MyClass works, except with the case statement values and data in XML.

The goal is to make the case statement values and data changeable without recompiling!

Simply, all the following should fill the class properties with the Joe Dee values
MyClass(1);
MyClass(2);
MyClass(100);
MyClass(200);

EXACTLY like the above MyClass does ...

Michael Taylor 51,346 Reputation points

2022-04-08T16:18:37.087+00:00

Please use the Comment button to respond to answers so we can more easily relate your response. Thanks.

Do you care about the XML format at all? If not then this becomes quite a bit simpler to solve.

Michael Taylor 51,346 Reputation points

2022-04-08T16:51:51.603+00:00

Here's a first pass at what your original XML might look like given the existing type definition. Note that you need an extra type because XML requires a root item.

public class MyClass { [XmlAttribute] public int Id { get; set; } [XmlAttribute] public string FirstName { get; set; } [XmlAttribute] public string LastName { get; set; } [XmlAttribute] public bool Employee { get; set; } [XmlAttribute] public int Location { get; set; } public string Description { get; set; } } [XmlRoot("Root")] public class MyClassRoot { [XmlArray] [XmlArrayItem(ElementName = "User")] public List<MyClass> Users { get; set; } }

And the reading code.

var serializer = new XmlSerializer(typeof(MyClassRoot)); using (var reader = new StreamReader(xmlFile)) { var users = serializer.Deserialize(reader); };

Michael Taylor 51,346 Reputation points

2022-04-08T16:51:59.02+00:00

And the corresponding XML file.

<?xml version="1.0" encoding="utf-8" ?> <Root> <Users> <User Id="1" FirstName="Joe" LastName="Dee" Employee="true" Location="11"> <Description>Bla Bla Bla</Description> </User> <User Id="2" FirstName="Joe" LastName="Dee" Employee="true" Location="11"> <Description>Bla Bla Bla</Description> </User> <User Id="3" FirstName="Jane" LastName="Doe" Employee="false" Location="11"> <Description>Bla Bla Bla</Description> </User> <User Id="3" FirstName="Jane" LastName="Doe" Employee="false" Location="11"> <Description>Bla Bla Bla</Description> </User> </Users> </Root>

Csick 21 Reputation points

2022-04-08T19:00:27.247+00:00

Yes sir, Sorry, didn't know about the comment option.

If I read your suggestion correctly, it would have many records of the same data with different id's ;) ??
And I could not figure out how to use it, how do I pass in the ID I want ??

I need to go the other way, many id's to one data record!
And it could be hundreds or thousands of ID's for the one record.

That is the purpose of IDS, it is an ID lookup table that shares a unique id with a single USER record.
Lookup up the ID in IDS, use the UniqueID from IDS to lookup the one USER record with matching UniqueID and load the values into the class properties.
That is just a thought of mine on how to get it done ...

I need EXACTLY how the posted current technique 'MyClass' works ... It does not use xml, I want it to!

I do not care what the xml file format is as long as it does not have hundreds of records of the same data with different id's.

I only need one record at a time, not an array or the whole file ... Linq like maybe, that's what I've been trying.

Michael Taylor 51,346 Reputation points

2022-04-08T20:12:44.153+00:00

Unfortunately the existing XML serialization support in .NET does not support the concept of object identification and hence it'll create a separate object for each element. The generally recommended way of working around that is to do the mapping post-deserialization using a dictionary. You have to write all this code yourself though as there is nothing in the framework that would help you.

But you've changed the requirements a little bit on me so now it sounds like you want to load only a single ID and not the entire dataset. In that case XML serialization is a mute point as it'll load everything. If you want to stick with XML then you'll need to switch to using an XML reader (or LINQ to XML as you mentioned). In this case you are going to have to map the XML yourself so identity is not really relevant here.

var doc = XDocument.Load(xmlFile); var id = 2; var users = from i in doc.Root.Descendants("Id") join u in doc.Root.Descendants("User") on i.Value equals u.Attribute("Id")?.Value where i.Attribute("id").Value == id.ToString() select new { Id = i, User = new MyClass { Id = u.Attribute("Id").Value, FirstName =u.Attribute("FirstName").Value, LastName =u.Attribute("LastName").Value } }; var user = users.FirstOrDefault(); var name = user?.User;

Note this kind of XML parsing needs lots of error handling.

Michael Taylor 51,346 Reputation points

2022-04-08T20:13:02.273+00:00

XML file.

<?xml version="1.0" encoding="utf-8" ?> <Root> <Ids> <Id id="1">user1</Id> <Id id="2">user2</Id> </Ids> <Users> <User Id="user1" FirstName="Joe" LastName="Dee" Employee="true" Location="11"> <Description>Bla Bla Bla</Description> </User> <User Id="user2" FirstName="Jane" LastName="Doe" Employee="false" Location="11"> <Description>Bla Bla Bla</Description> </User> </Users> </Root>

Csick 21 Reputation points

2022-04-09T16:35:18.587+00:00

Nothing about my question has changed, I still want EXACTLY what is written in my original question.
An XML technique that mimics MyClass.
Maybe how I've said it has, but the end results are exactly the same.

What has changed is your understanding of my question ... There is clearly a misunderstanding.

May I recommend you start a new form project, add a button to the form, add the buttons implementation, open Form1.cs and place using System.Diagnostics; at the top, then just inside the namespace, copy/paste MyClass from my question, then in button_click(...) add the following code, build and run ... take note of the output in the Debug console!

MyClass myclass= new MyClass(1); Debug.WriteLine($"FirstName: {myclass.FirstName}"); Debug.WriteLine($"LastName: {myclass.LastName}"); myclass = new MyClass(2); Debug.WriteLine($"FirstName: {myclass.FirstName}"); Debug.WriteLine($"LastName: {myclass.LastName}"); myclass = new MyClass(3); Debug.WriteLine($"FirstName: {myclass.FirstName}"); Debug.WriteLine($"LastName: {myclass.LastName}"); myclass = new MyClass(4); Debug.WriteLine($"FirstName: {myclass.FirstName}"); Debug.WriteLine($"LastName: {myclass.LastName}");

Michael Taylor 51,346 Reputation points

2022-04-09T19:48:17.44+00:00

The first code block I gave allows you to load your class from XML if you wanted to load all the data. The second code block does the same thing except it allows a LINQ-style query to load just the record(s) you want.

If neither of these solve your problem then perhaps someone else can respond and provide you better suggestions. I'm out of additional suggestions for you. Good luck.

Csick 21 Reputation points

2022-04-09T20:56:26.497+00:00

Your first bit of code does not provide the requested results, to mimic MyClass in operation, and I'll add without creating hundreds if not thousands of the same records with different id's.

Your second bit of code does not work, maybe I am not using it correctly ... The example is not clear.
I get null and or the object name.

The xml is a copy/paste of your example.

Csick 21 Reputation points

2022-04-09T21:31:37.427+00:00

I think I figured out how to use your last bit ... At least I got an expected result, I can at least work with it and see if it does the job for me ...

I will respond with further details after I work with it a bit.

Thank you.

Csick 21 Reputation points

2022-04-10T14:52:29.09+00:00

This is what I came up with, please tell me there is a better way.

public class MyClass { public string FirstName { get; private set; } public string LastName { get; private set; } private class MyClassInfo { public string Id { get; set; } public string FirstName { get; set; } public string LastName { get; set; } public bool Employee { get; set; } public int Location { get; set; } public string Description { get; set; } } public MyClass(int id) { string filename = @"..\..\Xml\Users.xml"; var doc = XDocument.Load(filename); var users = from i in doc.Root.Descendants("Id") join u in doc.Root.Descendants("User") on i.Value equals u.Attribute("Id")?.Value where i.Attribute("id").Value == id.ToString() select new { Id = i, User = new MyClassInfo { Id = u.Attribute("Id").Value, FirstName = u.Attribute("FirstName").Value, LastName = u.Attribute("LastName").Value, } }; var user = users.FirstOrDefault(); var name = user?.User; FirstName = user.User.FirstName; LastName = user.User.LastName; } }

Of course I need to add the rest of the attributes and value.

Csick 21 Reputation points

2022-04-10T14:55:15.553+00:00

And because this ignorant site has a 1600 byte limitation ...

It's test case usage ...

private void button1_Click(object sender, EventArgs e) { int id = 2; MyClass myclass = new MyClass(id); Debug.WriteLine($"FirstName: {myclass.FirstName}"); Debug.WriteLine($"LastName: {myclass.LastName}"); }

Jack J Jun 24,496 Reputation points Microsoft Vendor

2022-04-14T10:10:07.927+00:00

@Csick ,
This is what I came up with, please tell me there is a better way.

I would like to know what aspects of your code you currently want to optimize.

Csick 21 Reputation points

2022-04-17T10:16:33.423+00:00

It would be nice to get rid of MyClassInfo if possible and just assign the values to the properties of MyClass.

Also is it possible to change the XML format to,

<Root> <Ids> <Id id="1">user1</Id> <Id id="2">user2</Id> </Ids> <Users> <User Id="user1"> <FirstName>Joe</FirstName> <LastName>Dee</LastName> <Employee>True</Employee> <Location>11</Location> <Description>Bla Bla Bla</Description> </User> <User Id="user2"> <FirstName>Jane</FirstName> <LastName>Doe</LastName> <Employee>false</Employee> <Location>11</Location> <Description>Bla Bla Bla</Description> </User> </Users> </Root>

I have tried without success.

Something I only eluded to in the original question and I probably should have been more clear about, is it needs to be a drop in replacement for my MyClass example in my original question.

I apologize for that oversight ...

Thank you.

Csick 21 Reputation points

2022-04-19T04:51:43.217+00:00

Much better, still would like to see MyClassInfo gone ...
@Michael Taylor Thank you for getting me going!

public class MyClass { public string FirstName { get { return userInfo.FirstName; } private set { userInfo.FirstName = value; } } public string LastName { get { return userInfo.LastName; } private set { userInfo.LastName = value; } } private MyClassInfo userInfo = new MyClassInfo(); private class MyClassInfo { public string FirstName { get; set; } public string LastName { get; set; } } public MyClass(int id) { string filename = @"..\..\Xml\Users.xml"; var doc = XDocument.Load(filename); var users = from i in doc.Root.Descendants("Id") join u in doc.Root.Descendants("User") on i.Value equals u.Attribute("Id")?.Value where i.Attribute("id").Value == id.ToString() select new { User = new MyClassInfo { FirstName = u.Element("FirstName")?.Value, LastName = u.Element("LastName")?.Value, } }; userInfo = users.FirstOrDefault()?.User; } }
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C# class with Many to One XML data

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