VB.Net GPX to Datatable

Question

I am trying to convert a GPX file to a datatable but seem to be really struggling with the basics of this. A GPX file is just an XML for GPS data. I have managed to put the URI of the file into a variable with a dialog box.

Here is the GPX file I am trying to load (albeit with a reduced number of points):

<?xml version="1.0" encoding="UTF-8" standalone="no" ?>
<gpx xmlns="http://www.topografix.com/GPX/1/1"
xmlns:gpxx="http://www.garmin.com/xmlschemas/GpxExtensions/v3"
xmlns:gpxtpx="http://www.garmin.com/xmlschemas/TrackPointExtension/v1"
xmlns:badelf="http://bad-elf.com/xmlschemas"
version="1.1"
creator="Bad Elf GPS Pro+ 2.1.50"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.topografix.com/GPX/1/1 http://www.topografix.com/GPX/1/1/gpx.xsd http://www.garmin.com/xmlschemas/GpxExtensions/v3 http://www.garmin.com/xmlschemas/GpxExtensionsv3.xsd http://www.garmin.com/xmlschemas/TrackPointExtension/v1 http://www.garmin.com/xmlschemas/TrackPointExtensionv1.xsd http://bad-elf.com/xmlschemas http://bad-elf.com/xmlschemas/GpxExtensionsV1.xsd">
    <metadata>
    <extensions>
    <badelf:modelNickname>BE021</badelf:modelNickname>
    <badelf:modelSerialNumber>011215</badelf:modelSerialNumber>
    <badelf:modelName>Bad Elf GPS Pro+</badelf:modelName>
    <badelf:modelNumber>BE-GPS-2300</badelf:modelNumber>
    <badelf:modelHardwareRevision>8.0.0</badelf:modelHardwareRevision>
    <badelf:modelFirmwareRevision>2.1.50</badelf:modelFirmwareRevision>
    <badelf:elevationSource>gps</badelf:elevationSource>
    </extensions>
    </metadata>
    <wpt lat="50.650192" lon="-1.186149">
    <ele>10.3</ele>
    <time>2021-07-24T14:47:40Z</time>
    <name>START (2021-07-24T14:47:40Z)</name>
    </wpt>
    <trk>
    <name>2021-07-24T14:47:40Z</name>
    <trkseg>
    <trkpt lat="50.650192" lon="-1.186149"><ele>10.3</ele><time>2021-07-24T14:47:40Z</time><hdop>0.9</hdop><extensions><badelf:speed>0.00</badelf:speed><badelf:baroEle>52.4</badelf:baroEle><badelf:baroPress>1005.81</badelf:baroPress></extensions></trkpt>
    <trkpt lat="50.650195" lon="-1.186144"><ele>8.8</ele><time>2021-07-24T14:47:41Z</time><hdop>0.9</hdop><extensions><badelf:speed>0.00</badelf:speed><badelf:baroEle>52.4</badelf:baroEle><badelf:baroPress>1005.81</badelf:baroPress></extensions></trkpt>
    <trkpt lat="50.650193" lon="-1.186146"><ele>8.9</ele><time>2021-07-24T14:47:41Z</time><hdop>0.9</hdop><extensions><badelf:speed>0.00</badelf:speed><badelf:baroEle>52.4</badelf:baroEle><badelf:baroPress>1005.81</badelf:baroPress></extensions></trkpt>
    </trkseg>
    </trk>
    <wpt lat="50.650168" lon="-1.186119">
    <ele>13.4</ele>
    <time>2021-07-24T15:52:30Z</time>
    <name>END (2021-07-24T15:52:30Z)</name>
    </wpt>
    </gpx>

What I would like is to extract the badelf:modelNickname to a variable and then make a datatable with column headings "lat" "lon" "ele" "time" "hdop" "badelf:speed" and "badelf:baropressure"

Can someone help me do this in VB.Net please? Or even C# as I can probably translate.

When you say datatable, do you mean, in-memory (without a database) `DataTable` so you can attach it to a grid, or do you want to insert this into a database? — tgolisch, Sep 28 '21 at 14:34
Yes, in-memory datatable. I will write it to SQL Express later when I trimmed the data. I have managed to readxml into a dataset but this feels messy and will presumably only work with this exact schema. A different GPS would probably produce different results. — mbs485184, Sep 29 '21 at 07:21

score 0 · Answer 1 · answered Sep 29 '21 at 14:00

If you want to do this without a library to help you extract the XML, you could use Dmitry Bychenko's recommendation in this SO post that shows how to take a substring between two "words".

Since your parameters will always have the same name, you could just replace the words in his example with the beginnings and endings of each parameter line.

This is how you could extract your badelf:modelNickname to a variable.

As for your datatable, I'm not sure what you're filling it with but if you just need a datatable with those columns, you can do so like @RKK's answer on this SO Post:

Dim dt As New DataTable

dt.Columns.Add("Id", GetType(Integer))
dt.Columns.Add("FirstName", GetType(String))
dt.Columns.Add("LastName", GetType(String))

dt.Rows.Add(1, "Test", "data")
dt.Rows.Add(15, "Robert", "Wich")
dt.Rows.Add(18, "Merry", "Cylon")
dt.Rows.Add(30, "Tim", "Burst")

Let me know if that gets you closer to your goal or not.

score 0 · Answer 2 · answered Sep 29 '21 at 14:07

There aren't any open-source projects that already do this. So I can offer some good examples that you can consider and extract code from. Both will require some development.

Jim Jackson from Microsoft had a good blog post on March 11, 2009 which was loaded with good source code showing how to use LINQ, to query various elements from a GPX file.

GpxReader is an open-source library from DLC. It has some good examples for extracting elements from a gpx file. Comments at the bottom had some good ideas for next-steps.

You could use either of those to extract the elements that you want and insert them into a datatable, etc. The code examples are in C#, but can be converted to VB.NET with one of the popular (online) code converters. LINQ in VB.NET can be a little awkward sometimes. It depends on your skills/experience.

Hi. Thanks for getting back to me. I'm very much an amateur so LINQ may not be the best solution for me. I will have a look at GpxReader and see if that helps. Since posting, I have managed to readxml the file into a dataset and then extracted the data from the dataset into a single data table. Only downside of this is I am sure the table number that the data ends up in will vary depending on the schema so my solution will probably only work with this exact schema. — mbs485184, Oct 01 '21 at 08:19

VB.Net GPX to Datatable

2 Answers2