[mapguide-users] Layer Filter

[sairam]

I have managed code for Layer Filter task. 

I passing a filter condition as parameter for the selected layer and I get
the filtered layer on the map.
But the problem I persist is the layer definition xml is getting permanently
altered even though I make a copy to session repository before altering the
layer definition and use the session layer definition for altering it with
the filter condition.

I couldn't trace out where I have went wrong in my code.

Given below is the code:

public String SetFilter(MgResourceService resourceService,
MgResourceIdentifier ResID, String sNodeToFind, String QueryString)
 
    {
        String sNewFilter = "";
        
        // Load the mapguide resource into an xml DOM document
        XmlDocument doc = loadResourceXML(resourceService, ResID);
        XmlElement baseRootNode = doc.DocumentElement;

        //Select all nodes
        bool bChanged = false;

        XmlNodeList nodeList = baseRootNode.SelectNodes(sNodeToFind);

       //Update if it exists
        if (nodeList.Count != 0)
        {
            for (int i = 0; i < nodeList.Count; i++)
            {
                XmlNode node = nodeList.Item(i);
                String sOldString = node.FirstChild.Value;
                node.FirstChild.Value = sOldString.Replace(sOldString,
QueryString);
                sNewFilter = node.FirstChild.Value;
                bChanged = true;
            }
        }
       //Create a New Filter Node if it does not exists

        if (nodeList.Count == 0)
        {
           
         
           

            XmlNode FilterNode = doc.CreateNode(XmlNodeType.Element,
"Filter", string.Empty);
            FilterNode.InnerText = QueryString;
            XmlElement rootNode = doc.DocumentElement;

            XmlNodeList nodelist1 =
doc.DocumentElement.GetElementsByTagName("LegendLabel");


            for (int i = 0; i < nodelist1.Count; i++)
            {
                XmlNode node = nodelist1.Item(i);


                XmlNode FinalNode = node.ParentNode;
                FinalNode.InsertAfter(FilterNode, node);
                bChanged = true;
                sNewFilter = FilterNode.InnerText;

            }
        }





        
        if (bChanged)
        {
            MgByteSource byteSrc = ByteSourceFromXMLDoc(doc);
            resourceService.SetResource(ResID, byteSrc.GetReader(), null);
        }

        return sNewFilter;


    }

public XmlDocument loadResourceXML(MgResourceService resourceService,
MgResourceIdentifier ResID)
    {
        // Get the content of the resource
        string xmlDef =
resourceService.GetResourceContent(ResID).ToString();
        byte[] byteDef = new byte[xmlDef.Length];
        int iByteCount = Encoding.UTF8.GetBytes(xmlDef, 0, xmlDef.Length,
byteDef, 0);

        // Load the content into an XMLDOM object
        XmlDocument xmlDoc = new XmlDocument();
        xmlDoc.PreserveWhitespace = true;
        xmlDoc.LoadXml(xmlDef);
        return xmlDoc;
        //throw new System.NotImplementedException();
    }


public MgByteSource ByteSourceFromXMLDoc(XmlDocument xmlDoc)
    {
        //Save the amended DOM object to a memory stream
        MemoryStream XmlStream = new MemoryStream();
        xmlDoc.Save(XmlStream);

        //Now get the memory stream into a byte array that can be read into
an MgByteSource
        byte[] byteNewDef = XmlStream.ToArray();
        String sNewDef = new String(Encoding.UTF8.GetChars(byteNewDef));
        byte[] byteNewDef2 = new byte[byteNewDef.Length - 1];
        int iNewByteCount = Encoding.UTF8.GetBytes(sNewDef, 1,
sNewDef.Length - 1, byteNewDef2, 0);
        MgByteSource byteSource = new MgByteSource(byteNewDef2,
byteNewDef2.Length);
        byteSource.SetMimeType(MgMimeType.Xml);
        return byteSource;
    }


public void SetResourceValue(MgResourceService resourceService,
MgResourceIdentifier ResID, String sNodeToFind, String sNewValue)
    {
        // Load the mapguide resource into an xml DOM document
       
        XmlDocument doc = loadResourceXML(resourceService, ResID);
        XmlElement baseRootNode = doc.DocumentElement;

        //baseRootNode.SelectSingleNode(sNodeToFind).FirstChild.Value =
sNewValue;

        //Alternative to above, change all nodes
        bool bChanged = false;
        XmlNodeList nodeList = baseRootNode.SelectNodes(sNodeToFind);
        for (int i = 0; i < nodeList.Count; i++)
        {
            XmlNode node = nodeList.Item(i);
            String sOldString = node.FirstChild.Value;
                      

           //swap the session layer resource id for the original resource id
in the runtime map

            node.FirstChild.Value = sOldString.Replace(sOldString,
sNewValue);
            bChanged = true;
        }

        // create an MgByteSource from the XML DOM document and commit the
changes
        if (bChanged)
        {
           
            MgByteSource byteSrc = ByteSourceFromXMLDoc(doc);
            resourceService.SetResource(ResID, byteSrc.GetReader(), null);
           
        }
    }

public bool UpdateFiltersRes(MgResourceIdentifier mapResID, string
QueryString, MgResourceService res, String sessID, MgLayer LayerName)
    {
        bool bUpdated = false;
        string sFilterLayer = LayerName.Name;
        String sNewFilter;
        XmlDocument docMap = loadResourceXML(res, mapResID);
        XmlElement rootNode = docMap.DocumentElement;
        XmlNode node = rootNode.SelectSingleNode("//MapLayer[Name='" +
sFilterLayer + "']"); 
                                                                                             
     

     
            if (node != null)
            {
                // Get the resource identifier for each layer

                XmlNode resourceID = node.SelectSingleNode("ResourceId");
                String sLayerDef = resourceID.FirstChild.Value;
                MgResourceIdentifier layerResID = new
MgResourceIdentifier(sLayerDef);

                
		// Create a copy in the Session repository and update the filter

               MgResourceIdentifier sessionLayerResID =
CreateSessionResource(res, layerResID, sessID);
        

                ////Calling SetFilter Function here with Session
Copy(sessionLayerResID)

 

                sNewFilter = SetFilter(res, sessionLayerResID, "//Filter",
QueryString);

                if (sNewFilter != "" && sNewFilter != null)
                {
                  
                    bUpdated = true;

                    ////////////////////// save or Alter the map with the
amended session layer definition

                    String sXpath = String.Concat("//MapLayer/ResourceId[. =
\"", layerResID.ToString(), "\"]");
            
                   SetResourceValue(res, mapResID, sXpath,
sessionLayerResID.ToString());
         
                    
                }
           
               
            }

        
        return bUpdated;


    }













Please help me out on this regards.

Many Thanks,

Ram
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