Adding data to existing XML file?

Unity Engine
1

Hi,

I’m trying to add new elements to my XML file in which I store strings. The user can look up these strings in a search panel, but also can add a new element if it’s not in the list.
I’ve tried adding a String but it doesn’t seem to be working. Here’s the code:

AXML.Load(Application.persistentDataPath + "/" + "XML" + "/ActivitiesDatabase.xml");

public void AddActivity(string act)
{
	Debug.Log ("Adding activity to XML");
	XmlElement elmNew = AXML.CreateElement("activityData");
	XmlElement elmDesc = AXML.CreateElement("Activity_Description");
	elmDesc.InnerText = act;
	AXML.Save(Application.persistentDataPath + "/" + "XML" + "/ActivitiesDatabase.xml");
}

And a snippet of the XML file:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<!DOCTYPE Activites [
   <!ATTLIST activityData id ID #REQUIRED>
]>
<Activities xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<activityData id="Aerobics">
		<Activity_Description>Aerobics</Activity_Description>
	</activityData>
</Activities>

This is just the basic XML file, there could be more information added to it in the future. The idea is to add new activityData to the XML file and save that file overwriting the original file.

2

anyone?

3

Hi!
You create new element, but forget to add it to the xml document (with AppendChild(elmNew) method)
See example of using CreateElement() method it the MSDN help - XmlDocument.CreateElement Method (System.Xml) | Microsoft Learn

Good luck!

4

Hi Patico,

Thanks for your reply! I’ve added the following code:

public void AddActivity(string act)
{
		Debug.Log ("Adding activity to XML");
		XmlElement elmNew = AXML.CreateElement("activityData");
		XmlElement elmDesc = AXML.CreateElement("Activity_Description");
		elmDesc.InnerText = act;
		AXML.AppendChild(elmNew);
                AXML.AppendChild(elmDesc);
		AXML.Save(Application.persistentDataPath + "/" + "XML" + "/ActivitiesDatabase.xml");
}

Getting the following error:

5

Yes, almost correct. You tried to add ‘elmNew’ to the root of the xml document, but this is prohibited. You should before get an element where you want to place ‘elmNew’ and append ‘elmNew’ to it.

I don’t test, but finil code should e like this:

    public void AddActivity(string act)
    {
            Debug.Log ("Adding activity to XML");
            XmlElement elmNew = AXML.CreateElement("activityData");
            XmlElement elmDesc = AXML.CreateElement("Activity_Description");
            elmDesc.InnerText = act;

            XmlElement elem = AXML.GetElementById("Aerobics"); // or you can use GetElementsByTagName(String) method 
            elem.AppendChild(elmNew);
            elem.AppendChild(elmDesc);
            AXML.Save(Application.persistentDataPath + "/" + "XML" + "/ActivitiesDatabase.xml");
    }

Whole list of methods and examples see here: XmlDocument Class (System.Xml) | Microsoft Learn

6

Hi Patico,

Thanks for your reply! But this way i’m adding a new element to the Aerobics activity right? I want to add a new activity to the Activities section.

7

Just to make my question a bit clearer, let’s say I want to add the code below to my existing XML.

<activityData id="Soccer">

        <Activity_Description>Soccer</Activity_Description>

</activityData>

I think I know how to add this, except for he <activityData id="Soccer"> part. I don’t know how to add the id=“” to the element.

EDIT
Fixed it here’s my code:

public void AddActivity(string act)
{
	string temp = char.ToUpper(act[0]) + act.Substring(1);		//Sets the first char in the string to Upper case
	searchFor = temp;
	foundActivities = ReadActivitiesNode("Activities/activityData/Activity_Description");

        //Check if activity does not exist in the XML
	if(!foundActivities.Contains(temp))
	{
			Debug.Log ("No activity found! Adding activity to XML");
			XmlElement root = AXML.DocumentElement;
			XmlElement elmNew = AXML.CreateElement("activtyData");
			elmNew.SetAttribute("id", temp);
			XmlElement elmDesc = AXML.CreateElement("Activity_Description");
			elmDesc.InnerText = temp;
			root.AppendChild(elmNew);
			elmNew.AppendChild(elmDesc);
			AXML.Save(Application.persistentDataPath + "/" + "XML" + "/ActivitiesDatabase.xml");
	}
	else
	{
			Debug.Log ("Activity already exists!");
	}
}
8

Fixed it :slight_smile:

Here’s the final code:

public void AddActivity(string act)
	{
		string temp = char.ToUpper(act[0]) + act.Substring(1);		//Sets the first char in the string to Upper case
		searchFor = temp;
		foundActivities = ReadActivitiesNode("Activities/activityData/Activity_Description");

		if(!foundActivities.Contains(temp))
		{
			Debug.Log ("No activity found! Adding activity to XML");

			XmlElement root = AXML.DocumentElement;
			XmlElement elmNew = AXML.CreateElement("activtyData");
			XmlElement elmDesc = AXML.CreateElement("Activity_Description");

			elmNew.SetAttribute("id", temp);
			elmDesc.InnerText = temp;

			root.AppendChild(elmNew);
			elmNew.AppendChild(elmDesc);

			AXML.Save(Application.persistentDataPath + "/" + "XML" + "/ActivitiesDatabase.xml");
		}
		else
		{
			Debug.Log ("Activity already exists!");
		}
	}

Edit:
There seems to be one problem now. The XML is created and the new activitydata is added. But when i’m searching for it, there’s no item with the name added to the XML :frowning: seems like the XML is not reloaded.
I’ve added this code but that doesn’t seem to work:

Which basically just reloads the XML to the AXML variable. But this doesn’t seem to work. Also when I restart the app the added string still isn’t findable.

Edit2:
The only thing i’m thinking of what can cause this, is that the XML is not sorted because the node will be added at the end of the root element.
Is there a way to simply sort an XML file?

Edit3:
Fixed it made a typo in the element name :smile: