Query Features with a filter

This page describes how to use the MaestroAPI from the MapGuide Maestro project in your own application.

This sample shows how to read geometry features from a FeatureSource using MaestroAPI.

(C#)

using OSGeo.MapGuide.MaestroAPI;
...

//Read the setup, either from QueryString, Form, Cookies or hardcoded values
string username = Request.Params("USERNAME") == null ? "Anonymous" : Request.Params("USERNAME");
string password = Request.Params("PASSWORD") == null ? "" : Request.Params("PASSWORD");
string layout = Request.Params("LAYOUT") == null ? "Library://MyLayout.WebLayout" : Request.Params("LAYOUT");
string locale = Request.Params("LOCALE") == null ? "en" : Request.Params("LOCALE");
string sessionid = Request.Params("SESSION");


//Variables that should be replaced
string serverUrl = "http://localhost/mapguide/mapagent/mapagent.fcgi";
string featureSourceId = "Library://my data source.FeatureSource";
string classname = "Default:Test";
string filter = "ID = 5 AND Y LIKE 'test*'";

//Setup connection
Uri host = new Uri(serverUrl);
ServerConnectionI con;

//Either use session id or explicit credentials
if (string.IsNullOrEmpty(sessionid))
    con = new HttpServerConnection(host, username , password, locale, true);
else
    con = new HttpServerConnection(host, sessionid, true);

//Get the featuresource
FeatureSource fs = con.GetFeatureSource(featureSourceId);
FeatureSourceDescription desc = fs.DescribeSource(classname);

//Find the geometry column
FeatureSetColumn geometryColumn = null;
foreach(FeatureSetColumn col in desc.Schemas[0].Columns)
    if (col.Type == MaestroAPI.Utility.GeometryType)
        geometryColumn = col; //TODO: If there are more than one?

//Add any extra columns that you need
string[] columns = new string[] { geometryColumn.Name };

//Prepare a list
List<Topology.IO.Geometry.IGeometry> features = new List<Topology.IO.Geometry.IGeometry>();

//Execute the query
using (FeatureSetReader rd = fs.SelectFeatures(classname, filter, columns))
    while (rd.Read())
        features.Add(rd.Row[geometryColumn.Name] as Topology.IO.Geometry.IGeometry);

//The list "features" is now a list of all geometry found by applying the filter.