Question

I have the following xml file:

<Object type="User">
    <Attribute name="Name">usernameExample</Attribute>
    <Attribute name="Title">FHen</Attribute>
    <Attribute name="AdministratedBy">Admin</Attribute>
    <Attribute name="Password">123</Attribute>
    <Attribute name="TimeOut">00:20:00</Attribute>
    <Object type="AreasFolder">
        <Attribute name="Name">Areas</Attribute>
        <Attribute name="Comment">This folder contains ...</Attribute>
        <Object type="Area">
            <Attribute name="Name">RootArea</Attribute>
            <Attribute name="AccessLevel">None</Attribute>
        </Object>
        <Object type="Area">
            <Attribute name="Name">FRF</Attribute>
            <Attribute name="AccessLevel">Admin</Attribute>
        </Object>
    </Object>
</Object>

and my goal is to get the name of the Areas which have AccessLevel != None by the user name. I already can get the Areas inside the user and I can filter them using c# logic but I would like to do that with a Linq Xml query.

Right now I've done the following:

In my main:

logic.tryXdoc("usernameExample");

In my Logic.cs:

public void tryXdoc(string username)
    {
        List<string> lista = new List<string>();

        XElement ConfigData = XElement.Load(UsersXmlPath);

        XElement scadaUsers =
            (from xElement in ConfigData.Elements("Object")
                 //where (string)xElement.Element("type") == "User"
             select xElement).First();

        XElement usersFolder =
            (from xElement in scadaUsers.Elements("Object")
             where (string)xElement.Attribute("type") == "UsersFolder"
             select xElement).First();

        IEnumerable<XElement> users =
             from xElement in usersFolder.Elements("Object")
             where (string)xElement.Attribute("type") == "User"
             select xElement;

        XElement user =
             (from xElement in users
              where (string)xElement.Element("Attribute").Attribute("name") == "Name"
              && (string)xElement.Element("Attribute") == username
              select xElement).First();

        XElement areasFolder =
             (from xElement in user.Elements("Object")
              where (string)xElement.Attribute("type") == "AreasFolder"
              select xElement).First();

        IEnumerable<XElement> areas =
             from xElement in areasFolder.Elements("Object")
             where (string)xElement.Attribute("type") == "Area"
             select xElement;        
    }

Now, I would like something like this:

        IEnumerable<XElement> visibleAreas =
             from xElement in areas.Elements("Attribute")
             where 
             (string)xElement.Attribute("name") == "AccessLevel"
             && (string)xElement.Attribute("name").Value != "None"
             select xElement;

And I would like to get only one Area, because there is just one with AccessLevel != "None" but I get the same result as areas. I don't know how to tell my program that the xElement.Attribute("name").Value that I want it to compare to "None" it the Value of the xElement.Attribute("name") that I compared with AccessLevel.

I have already tried to use Descendants().Where( something ) but I get the same. I tried to use Descendants().Where(something.Where( something else )) but I can't compile.

I can get the areas that I want using:

        List<List<XElement>> listAreaAttributes = new List<List<XElement>>();

        foreach (XElement xElement in areas)
        {
            List<XElement> areaAttributes = new List<XElement>();

            foreach (XElement xEl in xElement.Elements("Attribute"))
            {
                areaAttributes.Add(xEl);
            }

            listAreaAttributes.Add(areaAttributes);
        }

and then comparing the areaAttributes but I know it is possible to make this with a query so I don't want to use processment making this.

Answer 1

How about modifying this to fit your user, if you want to do it on a per-user bases. This assumes that the order of your XML is exact, and that the AccessLevel Name is always the node immediately previous to the AccessLevel.

List<string> visibleAreas = ConfigData.Descendants("Attribute")
    .Where(x => x.Attribute("name").Value == "AccessLevel")
    .Where(x => x.Value != "None")
    .Select(x => ((XElement)x.PreviousNode).Value)
    .ToList();

Xml Linq Query (get Element by Attribute and Attribute value)

1 个答案: