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Exercise outline
The goal of this exercise is to create and register a WaterML2 importer class. At the end, it should be possible to import WaterML2 files (containing time series data) into a Delta Shell project.
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Information on WaterML2, a global standard for hydrological time series, can be found at http://www.waterml2.org/. |
Create a new importer class
Add to the plugin project a new folder named Importers. In this folder, create a new class named WaterML2TimeSeriesImporter.cs and adapt the contents as shown below.
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In order to successfully build the code below, references need to be added to:
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\\ 1. Add a new folder to the project named "Importers" 2. Create a new class named "WaterML2TimeSeriesImporter" 3. Add the following contents to this class: {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.PluginPlugins.DemoAppVolumeModel.Importers { /// <summary> /// Importer for importing WaterML2 data to time series objects /// </summary> public class WaterML2TimeSeriesImporter : IFileImporter { private static readonly ILog logLog = 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 "DemoAppVolume 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. /// </remarks> public object ImportItem(string path, object target = null) { // Check the file path if (!File.Exists(path)) { logLog.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) { logLog.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; } } } {code} 4. Register the importer in the application plugin class by adding the following code to DemoAppApplicationPlugin: {code} |
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The importer class is derived from the IFileImporter interface so that it can be registered in the application plugin (see the next step). The comments in the code explain the different parts of the importer implementation. |
Register the importer in the application plugin class
Register the importer in the application plugin by adding the following code to VolumeModelApplicationPlugin.cs:
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using System.Collections.Generic;
using DeltaShell.Plugins.VolumeModel.Importers;
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public override IEnumerable<IFileImporter> GetFileImporters() { yield return new WaterML2TimeSeriesImporter(); } {code}5. Run the application, right click on Project and click Import. Select the newly implemented importer and press OK. \[TODO: Image\] 6. Select a file bla bla bla \[TODO:Image\] \\ } |
Delta Shell should now be able to find the importer when importing data on new or existing time series objects.
Exercise results
First of all, download the following WaterML2 XML: WaterML2_precipitation_data.XML.
Then, run the application and start importing a new project item (right click on project | Import...). Make sure that the new importer is selected in the dialog:
If you next click on OK, a file selection dialog pops up. Select the previously downloaded WaterML2 XML file and continue with the wizard.
After finishing the import, a new time series item, containing the data as shown in the following image, should be added to the project (double click the precipitation item in the Project window):
In the steps above, a project level import has been performed which creates a completely new time series item. The importer, however, is also able to import WaterML2 data into existing time series. Although this feature will be further used in some of the upcoming exercises, it can already be tested by sequentially:
- clearing (a part of) the imported time series data via the table view;
- importing the downloaded WaterML2 XML file directly onto this just modified time series item (right click on the time series item | Import ...).
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