Contents
Exercise outline
The goal of this exercise is to create and register a WaterML2 importer class. In the end it should be possible to import WaterML2 files (containing time series data) into a Delta Shell project.
Information on WaterML2, a global standard for hydrological time series, can be found here: http://www.waterml2.org/
Create a new importer class
Add a new folder to the plugin project named Importers. In this folder, create a new class named DemoAppApplicationPlugin.cs and add the following code:
using System;
using System.Collections.Generic;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Xml.Linq;
using DelftTools.Functions;
using DelftTools.Functions.Generic;
using DelftTools.Shell.Core;
using log4net;
namespace DeltaShell.Plugin.DemoApp.Importers
{
/// <summary>
/// Importer for importing WaterML2 data to time series objects
/// </summary>
public class WaterML2TimeSeriesImporter : IFileImporter
{
private static readonly ILog Log = LogManager.GetLogger(typeof(WaterML2TimeSeriesImporter)); // Handle for writing log messages
/// <summary>
/// The name of the importer
/// </summary>
/// <remarks>Used in importer selection dialogs</remarks>
public string Name
{
get { return "WaterML2 time series importer"; }
}
/// <summary>
/// The category of the importer
/// </summary>
/// <remarks>Used in importer selection dialogs</remarks>
public string Category
{
get { return "Volume model importers"; }
}
/// <summary>
/// The image of the importer
/// </summary>
/// <remarks>Used in importer selection dialogs</remarks>
public Bitmap Image
{
get { return new Bitmap(16, 16);}
}
/// <summary>
/// The data types supported by the importer
/// </summary>
public IEnumerable<Type> SupportedItemTypes
{
get { yield return typeof(TimeSeries); }
}
/// <summary>
/// Indicates that the importer can import at root level (folder/project). In other
/// words, indicates that the <see cref="ImportItem"/> method can be called without
/// specifying a time series target...
/// </summary>
public bool CanImportOnRootLevel
{
get { return true; }
}
/// <summary>
/// The file filter of the importer
/// </summary>
/// <remarks>Used in file selection dialogs</remarks>
public string FileFilter
{
get { return "WaterML2 files|*.XML"; }
}
/// <summary>
/// Path where external data files can be copied into
/// </summary>
/// <remarks>Not relevant in this tutorial</remarks>
public string TargetDataDirectory { get; set; }
/// <summary>
/// Whether or not an import task should be cancelled
/// </summary>
/// <remarks>Not part of this tutorial</remarks>
public bool ShouldCancel { get; set; }
/// <summary>
/// Fired when progress has been changed
/// </summary>
/// <remarks>Not part in this tutorial</remarks>
public ImportProgressChangedDelegate ProgressChanged { get; set; }
/// <summary>
/// Imports WaterML2 data from the file with path <paramref name="path"/> to the
/// time series <paramref name="target"/>
/// </summary>
/// <remarks>
/// The target parameter is optional. If a target time series is specified, the
/// importer should import the WaterML2 data to this existing time series. When
// no target is set, the importer should create a new time series during the import.
/// </remarks>
public object ImportItem(string path, object target = null)
{
// Check the file path
if (!File.Exists(path))
{
Log.Error("File does not exist");
return null;
}
// Obtain a new time series or check the provided target for being a time series
var timeSeries = target == null
? new TimeSeries { Name = Path.GetFileNameWithoutExtension(path), Components = { new Variable<double>() } }
: target as TimeSeries;
if (timeSeries == null)
{
Log.Error("Target is of the wrong type (should be time series)");
return null;
}
// Load the WaterML2 XML document
var doc = XDocument.Load(path);
// Obtain the document elements
var xElements = doc.Descendants();
// Obtain the measurement TVP tags
var measurements = xElements.Where(element => element.Name.LocalName == "MeasurementTVP");
// Get the corresponding time and value for each measurement tag
foreach (var measurement in measurements)
{
var time = DateTime.Parse(measurement.Elements().First(e => e.Name.LocalName == "time").Value);
var value = double.Parse(measurement.Elements().First(e => e.Name.LocalName == "value").Value);
timeSeries[time] = value;
}
// Return the time series
return timeSeries;
}
}
}
The importer class derives the IFileImporter interface so that it can be registered in the application plugin (see the next step).
Furthermore, the comments in the code should explain the different parts of the importer implementation.
Register the importer in the application plugin
Register the importer in the application plugin by adding the following code to VolumeModelApplicationPlugin.cs:
using DeltaShell.Plugin.DemoApp.Importers;
and
public override IEnumerable<IFileImporter> GetFileImporters()
{
yield return new WaterML2TimeSeriesImporter();
}
Delta Shell should now be able to find the importer when it comes to importing data on new or existing time series objects.
Exercise results
First of all, obtain the following WaterML2 XML file: WaterML2_precipitation_data.XML
Then run the application and start importing a new project item (right click on project | Import...). Ensure the new importer is visible in the importer selection dialog like shown in the following image:
[TODO]
After selecting the WaterML2 importer, a file selection dialog pops up. Select the obtained WaterML2 XML file.
After finishing the import action, a new time series item should be added to the project which holds data like shown in the following image:
[TODO]
In the steps above, a project level import is performed which results in the creation of a new time series item. The importer is, however, able to import WaterML2 data into existing time series too. Altough this feature will be used in some of the upcoming exercises, it can allready be tested now by sequentially:
- clearing (a part of) the imported time series data via the table view;
- importing the obtained WaterML2 XML file directly on the added time series item (right click on the time series item | Import ...).
