Resolved Wanting to add to XDocument to make more than one "entry" on a single write...

[Program4Food]

Wanting to add to XDocument to make more than one "entry" on a single write...

I think I am missing something here, not sure I understand how to do this.

I have some snippit code I massaged and got working fine, but when I add line ??? I get:

Severity Code Description Project File Line Suppression State
Error BC30452 Operator '+' is not defined for types 'XDocument' and 'XDeclaration'. vb-forms-dotnet 3.5 - xml 1 F:\VisualStudio\2015\vb-forms-dotnet 3.5 - xml 1\vb-forms-dotnet 3.5 - xml 1\Form1.vb 308 Active


I would appreciate insight on how to add another element with one write using LINQ, I had a hard enough time finding code that works just to write one element.

      ' used in original code, not used here  Dim empNM As XNamespace = "urn:lst-emp:emp"

        Dim xDoc As New XDocument(New XDeclaration("1.0", "UTF-16", Nothing), New XElement("Employees", New XElement("Employee", New XComment("Only 3 elements for demo purposes"), New XElement("EmpId", "5"), New XElement("Name", "Kimmy"), New XElement("Sex", "Female"))))

        ' try to add another element
        xDoc = xDoc + (New XDeclaration("1.0", "UTF-16", Nothing), New XElement("Employees", New XElement("Employee", New XComment("Only 3 elements for demo purposes"), New XElement("EmpId", "5"), New XElement("Name", "Kimmy"), New XElement("Sex", "Female"))))

        Dim sw As New System.IO.StringWriter()
        Dim xWrite As XmlWriter = XmlWriter.Create(sw)
        xDoc.Save(xWrite)
        xWrite.Close()

        ' Save to Disk
        xDoc.Save("F:\VisualStudio\DevResources\LINQxml-1.xml")
        Console.WriteLine("Saved")

 

[Program4Food]

I got this edited and resolved errors during edit, but generated run time error:

An unhandled exception of type 'System.InvalidOperationException' occurred in System.Xml.Linq.dll

Additional information: This operation would create an incorrectly structured document.

    ' try to add another element
        xDoc.Add(New XElement("Employees", New XElement("Employee", New XComment("This is my own comment"), New XElement("EmpId", "67"), New XElement("Name", "Shazam"), New XElement("Sex", "Male"))))

 

[jmcilhinney]

Can you give us an example of the XML structure that you're trying to achieve?

 

[Program4Food]

Here is what I am getting without adding line 6 in my original post, a well formed XML

<?xml version="1.0" encoding="utf-16"?>
<Employees>
  <Employee>
    <!--Only 3 elements for demo purposes-->
    <EmpId>5</EmpId>
    <Name>Kimmy</Name>
    <Sex>Female</Sex>
  </Employee>
</Employees>

This is what I was hoping to achieve with the addition of line 2 in the above post.

<?xml version="1.0" encoding="utf-16"?>
<Employees>
  <Employee>
    <!--Only 3 elements for demo purposes-->
    <EmpId>5</EmpId>
    <Name>Kimmy</Name>
    <Sex>Female</Sex>
  </Employee>
  <Employee>
    <!--This is my own comment-->
    <EmpId>67</EmpId>
    <Name>Shazam</Name>
    <Sex>Male</Sex>
  </Employee>
</Employees>

By the way, thank you for your time.

 

[Program4Food]

I am still fiddling with it but not resolved as of yet...

 

[JohnH]

These help pages should be useful: XML - Visual Basic
You'll see simpler ways to create, access and modify xml documents with literals. Browse through them to get a feel for working with xml using these tools.
Typically you create a new document and save it (or send it somewhere). Later load it (or get from womewhere), access some elements to modify them or add/remove them, then save again.
As remark in XDocument help page says, you don't typically create a document like you are trying, but instead build from XElement (with or without using xml literals).
In the case where you have the first document in post 4 and want to add another Employee you typically load the document, select the root (or whatever element(s) you want to manipulate) and add another XElement to it, then save.

 

[JohnH]

A quick sample how I would do this:

Dim id = 5, name = "Kimmy", sex = "Female"
Dim element = <Employees>
                  <Employee>
                      <EmpId><%= id %></EmpId>
                      <Name><%= name %></Name>
                      <Sex><%= sex %></Sex>
                  </Employee>
              </Employees>
Dim filename = "sample.xml"
element.Save(filename)

Note the xml is pure structural, I've used variables for the actual data.
The xml declaration with encoding is automatically added. Standard encoding is Utf-8. If I for some reason wanted Utf-16 (Unicode) I would save like this:

Using writer As New IO.StreamWriter(filename, False, System.Text.Encoding.Unicode)
    element.Save(writer)
End Using

Loading, adding a new element to root, saving again:

id = 67 : name = "Shazam" : sex = "Male"
Dim doc = XDocument.Load(filename)
doc.Root.Add(<Employee>
                 <EmpId><%= id %></EmpId>
                 <Name><%= name %></Name>
                 <Sex><%= sex %></Sex>
             </Employee>)
doc.Save(filename)

 

[Program4Food]

Ill take that and play with it! Thanks much!

 

[Program4Food]

That worked a treat!

The only thing I couldnt figure out was how to add a comment.

<?xml version="1.0" encoding="utf-16"?>
<Employees>
  <Employee>
    <!--Only 3 elements for demo purposes-->
    <EmpId>5</EmpId>
    <Name>Kimmy</Name>
    <Sex>Female</Sex>
  </Employee>
  <Employee>
    <EmpId>67</EmpId>
    <Name>Shazam</Name>
    <Sex>Male</Sex>
  </Employee>
</Employees>

using this code:

        Dim id As String = "67"
        Dim Name As String = "Shazam"
        Dim sex As String = "Male"
        'Dim comment As String = "This is a new comment"
        Dim filename As String = "F:\VisualStudio\DevResources\LINQxml-1.xml"

        Dim doc = XDocument.Load(filename)
        doc.Root.Add(<Employee>
                         <EmpId><%= id %></EmpId>
                         <Name><%= Name %></Name>
                         <Sex><%= sex %></Sex>
                     </Employee>)
        doc.Save(filename)

 

[Program4Food]

When I try to add a comment, I get this as the output:

  <Employee>
    <!-- <%= comment %> -->
    <EmpId>99</EmpId>
    <Name>Balto</Name>
    <Sex>Male</Sex>
  </Employee>
</Employees>

here is where I added the comment line, evidently I need to use an escape sequence??

        Dim id As String = "99"
        Dim Name As String = "Balto"
        Dim sex As String = "Male"
        Dim comment As String = "This is a new comment"
        Dim filename As String = "F:\VisualStudio\DevResources\LINQxml-1.xml"

        Dim doc = XDocument.Load(filename)
        doc.Root.Add(<Employee>
                         <!-- <%= comment %> -->
                         <EmpId><%= id %></EmpId>
                         <Name><%= Name %></Name>
                         <Sex><%= sex %></Sex>
                     </Employee>)
        doc.Save(filename)

 

[Program4Food]

Im looking at details on CDATA right now, not sure if Im going down the right rabbit hole yet...

 

[Program4Food]

Yup, I think Ive dead ended, Ive tried several things to try to add a COMMENT line with LINQ and getting no where.

 

[JohnH]

XML Comment Literal - Visual Basic

Learn more about: XML Comment Literal (Visual Basic)

docs.microsoft.com

Which means you can do this:

Dim element = <Employees>
                  <Employee>
                      <!-- comment -->
                      <EmpId><%= id %></EmpId>
                      <Name><%= name %></Name>
                      <Sex><%= sex %></Sex>
                  </Employee>
              </Employees>

Dynamic content (see remarks) means using XComment element, for example:

element...<Employee>.First().AddFirst(New XComment("dynamic comment"))

 

[Program4Food]

I tried that, just put it in the code as raw "<!-- This is a comment -->", but I would like to replace "This is a comment" with a string but I cant figure out how to do that

 

[JohnH]

I already showed you how to add comment with "dynamic content", that string is VB code that can be replaced with a variable.