Collectives on Stack Overflow. Learn more. Reading and writing to an xml file with VB. Net Ask Question. Asked 8 years, 9 months ago. Active 8 years, 9 months ago. Viewed 10k times. My first question: Is this XML valid? XmlDocument dom. Load "test. Empty For Each node As Xml. XmlNode In dom. InnerText ComboBox1. Add monitorid Next This is now where I am stuck. ReadXml "test. Improve this question. The naming of the XML elements is by default based on class names and property names but this can be separated from the model, if we decorate items accordingly [6].
A pit-fall to avoid here are direct references to parent items, because these would result into a circular structure, which cannot be serialized in XML this is a limitation of the XML format.
But this does not mean that we cannot have a parent pointer in the model, if we feel like we need one. We can simply apply the [XmlIgnore] [6] tag to the Parent property and get away with that because the Parent property is not needed for XML serialization or we can resolve the parent relationship by using a ParentId as shown in the code below assuming that Ids are unique over the complete tree structure.
The ParentId can be converted into a parent reference upon loading by using the foreach loop at the bottom of the second last listing together with a dictionary as previously explained for the Level-Order conversion.
The above serialization and de-serialization code requires the class of the root to be known and can be done between different "storage types", such as, string, file etc. So, that's the easy solution and it should be applicable as long as the structure is rather small a few thousand objects and public access to the objects that make up the model is not a problem. This is where the IXmlSerializable interface and the DataContractSerializer come to the rescue as we will see in the developments of the next sections.
The IXmlSerializable interface [7] must be implemented by the classes that represent the data model. There are then service classes, such as, the XMLSerializer or the DataContractSerializer , which use the defined interface methods to drive the serialization process for each object.
The interface requires 3 methods to be implemented:. The GetSchema method is required, but is already implemented, if it returns null. The other two methods require an implementation and are not so straight forward, especially when reading XML, because the read process should be flexible enough to handle different situations, but still be good enough to read everything correctly. A well known class that has been around since. Net 1.
XML is a self describing language and it gives the data as well as the rules to extract what the data it contains. In the previous program we create an XML file and named it as products. The following program read that file and extract the contents inside the XML tag. We can read an XML file in several ways depends on our requirement.
This program read the content in Node wise. In this program it search the Node and its child Nodes and extract the data in child nodes. Click here to download the input file : product. XmlReader is a faster and less memory consuming alternative. It provides a lower-level abstraction over the XML file structure. The XmlReader class allows you run through the XML string one element at a time, while allowing you to look at the value, and then moves on to the next XML element.
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