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writing an entity with child to xml
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Dominique View Drop Down
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Joined: 28-Jun-2007
Location: Norway
Posts: 44 		Post Options Post Options   Quote Dominique Quote  Post ReplyReply Direct Link To This Post Topic: writing an entity with child to xml
    Posted: 18-Sep-2007 at 12:22am
Hi,
I want to write a parent-childs hierarchy as an xml-file. I am wondering if there is a trivial way to achieve this with Ideablade?
I actually don't know the dotnet xml-API. I saw yesterday that datatable had method to do that but I didn't achieve my goal wich is basically 

sub WriteEntitty(anEntity as MyType)

anEntity = persistMng.getEntity(..)

anEntity.MagicMethodToXML(path, encoding)

the following structure for the xml file would be perfect: 

<parent>

<tblColumnname>value<\tblColumnname>

<tblColumnname>value<\tblColumnname>

  <evt- childtype1s> 

    <child type1>

      <tblColumnname>value<\tblColumnname>

    </child type1>

    <child type1>

      <tblColumnname>value<\tblColumnname>

    </child type1>

  </evt- childtype1s> 

  <evt- childtype2s> 

    <child type2>

      <tblColumnname>value<\tblColumnname>

      <tblColumnname>value<\tblColumnname>

    </child type2>

    <child type2>

      <tblColumnname>value<\tblColumnname>

      <tblColumnname>value<\tblColumnname>

    </child type2>

  </evt- childtype2s> 

</parent>


Dominique
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davidklitzke View Drop Down
IdeaBlade
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Joined: 14-Jun-2007
Posts: 715 		Post Options Post Options   Quote davidklitzke Quote  Post ReplyReply Direct Link To This Post Posted: 18-Sep-2007 at 8:55am

I would think that you would be able to use the DataSet.WriteXml method.
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Dominique View Drop Down
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Joined: 28-Jun-2007
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Posts: 44 		Post Options Post Options   Quote Dominique Quote  Post ReplyReply Direct Link To This Post Posted: 18-Sep-2007 at 12:18pm
Hi,
I tried the ado.Net writeXml one more time. :-)
I managed to somehow serialize the entities to a xml file.
The solution I found to pick up wich entities will be written to the file is to:
* create a dataset and clone the myEntity.dataset to get the structure
* make a list of datarows that I will fill by iterating the child collections of the entities
* merge the rows in the dataset
* call the writeXml method

The result would require a fair amount of Xquerying because the elements are all under the rotelement "newDataset" (no structure)

It wasn't so much work to write my own serializer, and the resulting file is much easier to parse, so I will stick with it. It also make it easier to not expose columns that should remain private.

That was the code I wrote, if of any interest... I wouldn't be surprised if it is a very wrong way to do it :). (example with 2 levels of nexting). 

Dim path As String = <thePath>

        Dim wrSettings As New XmlWriterSettings()

        With wrSettings

            .Indent = True

            .Encoding = Text.Encoding.UTF8

            .CloseOutput = True

            .ConformanceLevel = ConformanceLevel.Auto ' must have that

        End With

        Dim writer As XmlWriter = XmlWriter.Create(path, wrSettings)

        Using writer

            Try

                Dim ds As DataSet = context.Table.DataSet.Clone

                Dim rowList As New List(Of DataRow)

                rowList.Add(context)

                For Each child As MyChild In context.Childs

                    rowList.Add(child)

                    For Each grandchild As grandchild In MyChild.Childs

                        rowList.Add(grandchild)

                    Next

                Next



                Dim theRows As DataRow() = rowList.ToArray()

                ds.Merge(theRows)

                ds.WriteXml(writer, XmlWriteMode.IgnoreSchema)

                writer.Close()

            Catch ex As Exception

                Diagnostics.Debug.Print("Exception from xmlWriter: " & ex.Message) 'to get a good message

                Throw ex   ' caller's work

            End Try

           

        End Using
Dominique
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