topic Accessing Spatial Functionality from Plugin SDK in Dev Space

Accessing Spatial Functionality from Plugin SDK

SigIsaac — Thu, 10 May 2018 23:10:02 GMT

Hello Alteryx Developers,

I'm testing Alteryx Designer 2018.1 x64 to see if our company can integrate functionality from our software systems with Alteryx Designer as plug-in tools.

I've looked at the C++ and C# Custom Tools samples and have a basic idea of how the interface works. What I can't figure out is how to read and write spatial fields in a record. For example, our tools would have to be able to create polygons based on some input values based on the tool configuration and record values and then store them in the record as a spatial field. Looking through the C++ .h files and the .NET object browser for the AlteryxRecordInfo.NET and AlteryxGuiToolkit assemblies, I don't see anything that would allow me to do this.

I am new to the Alteryx world, so maybe I am looking in the wrong places. I would greatly appreciate anyone steering me in the right direction on this.

Many thanks in advance,

Sig Isaac

Re: Accessing Spatial Functionality from Plugin SDK

TashaA — Wed, 16 May 2018 15:06:05 GMT

Really great question @SigIsaac!

I'm reaching out to some of our architects to see what spatial capabilities (if any) can be accessed through the SDKs.

Re: Accessing Spatial Functionality from Plugin SDK

SigIsaac — Wed, 16 May 2018 22:49:15 GMT

Great! Look forward to any information you can provide.

Re: Accessing Spatial Functionality from Plugin SDK

RobertB — Thu, 17 May 2018 16:43:46 GMT

@SigIsaac -

In either the C++ or C# SDKs, you can read and write data to spatial fields using GetAsString() and SetFromString() and passing the object in GeoJSON format. These will do the same conversion that you get by switching a string to a spatial object (or vice-versa) using a Select tool in the Designer, so that's a good way to get an example of the string it is looking for.

In c++ you can also get/set spatial fields as blobs, but you can't do much of anything with the blob besides store it or set it to another field. So GeoJSON is the way to go if you want to create the spatial objects in the first place or crack open existing ones and manipulate them.

-Rob Bryan

Re: Accessing Spatial Functionality from Plugin SDK

SigIsaac — Thu, 17 May 2018 18:41:13 GMT

Thanks, Robert, I'll do some research on GeoJSON and give that a try.

Re: Accessing Spatial Functionality from Plugin SDK

SigIsaac — Fri, 25 May 2018 21:13:48 GMT

So I'm getting back to my work in developing a custom Alteryx tool and I'm taking Rob's advice of using GeoJSON strings to work with spatial fields. However, I find that when I try to set the value of a spatial field with FieldBase.SetFromString() an exception is thrown.

Here is a test code snippet from my II_PushRecord(AlteryxRecordInfoNet.RecordData pRecord) implementation:

AlteryxRecordInfoNet.FieldBase spatialField = m_recordInfoOut[inFieldCount]; // Previously created spatial field
spatialField.SetFromString(recordOut, "{ \"type\": \"Point\", \"coordinates\": [ -119.561378, 47.307156 ] }"); // THROWS EXCEPTION.

The exception error is pretty generic and does not provide much info: "External component has thrown an exception."

I got the GeoJSON string by looking at an existing point spatial record, so the format should be correct.

Is there perhaps a problem with the quotation marks in the GeoJSON string? Any suggestions would be appreciated.

Re: Accessing Spatial Functionality from Plugin SDK

TashaA — Thu, 14 Jun 2018 20:47:03 GMT

@RobertB, tagging you.

Re: Accessing Spatial Functionality from Plugin SDK

PaulN — Mon, 02 Jul 2018 18:45:37 GMT

Hey @SigIsaac,

From my experience, it's not possible to translate a string into a blob (or spatial blob directly).

SrcLib.dll provides ConvertFromGeoJSON (void ConvertFromGeoJSON(const char* pszJson, unsigned char **pSpatialObj, unsigned int *pLen)) that can convert a GeoJSON string into a spatial object. Then SetFromSpatialBlob() should help you to achieve your goals.

Unfortunately I don't have an example ready in C#/C++...

Thanks,

Paul Noirel

Sr Customer Support Engineer, Alteryx

Re: Accessing Spatial Functionality from Plugin SDK

SigIsaac — Mon, 16 Jul 2018 19:02:38 GMT

Thanks, Paul Noirel, tapping into the SrcLib.dll was the key to solving this problem. Many thanks for that suggestion. (It is a bit of a hack, though, and having that functionality available in the SDK would be preferable for the future.)

For anyone else needing similar functionality, here is a simplified version of my code.

bool ConvertFromGeoJSON(const std::string& geoJSON, unsigned char** spatialObj, unsigned int* blobSize)
{

typedef int(__cdecl *FunctionConvertGeoJSON)(const char* pszJson, unsigned char **pSpatialObj, unsigned int *pLen);

std::wstring pathSrcDll = L"C:\\Program Files\\AlteryxServer\\bin\\SrcLib.dll"; // Hard-coded for now

*spatialObj = nullptr;
*blobSize = 0;
bool success = false;

HINSTANCE hinstLib = LoadLibrary(pathSrcDll.c_str());
if (hinstLib != NULL)
{
ProcConvertGeoJSON = (FunctionConvertGeoJSON)GetProcAddress(hinstLib, "ConvertFromGeoJSON");
if (NULL != ProcConvertGeoJSON)
{
(ProcConvertGeoJSON)(geoJSON.c_str(), spatialObj, blobSize);
success = true;
}
FreeLibrary(hinstLib);
}

return success;

}

// Calling code in OutputDetailRecord()

...

const FieldBase* pFieldSpatialBlob = m_recordInfoOut.GetFieldByName(DriveTimeSpatialField.c_str(), true);

...

unsigned char* spatialBlob = nullptr;
unsigned int blobSize = 0;
if (ConvertFromGeoJSON(geoJSON, &spatialBlob, &blobSize))
{
SRC::BlobVal blobVal;
blobVal.pValue = spatialBlob;
blobVal.nLength = blobSize;

pFieldSpatialBlob->SetFromSpatialBlob(currentRecordOut.Get(), blobVal);
}

else

{

pFieldSpatialBlob->SetNull(currentRecordOut.Get());

}

Re: Accessing Spatial Functionality from Plugin SDK

PaulN — Tue, 17 Jul 2018 07:15:55 GMT

Great job @SigIsaac!!! Many thanks for sharing your code!

I will let @TashaA taking note of your point for the future of the SDK(s).

Have a nice day,

Paul Noirel

Sr Customer Support Engineer, Alteryx

Re: Accessing Spatial Functionality from Plugin SDK

SigIsaac — Tue, 17 Jul 2018 14:50:37 GMT

I don't know if this email will get to Paul Noirel, but if it does there is one small follow up point:

What is the signature for ConvertToGeoJSON, also in SrcLib.dll?

I ask this because FieldBase.GetAsString() does not provide the GeoJSON string for a spatial object, it just returns "SpatialObj" in the C++ SDK. In the .NET SDK, however, it does return the GeoJSON string. Since I've already committed to the C++ SDK, I need a workaround and ConvertToGeoJSON should do it if I can get the function parameter list.

Thanks,

Sig Isaac

Sig Isaac | Chief Software Architect
Tetrad | Geographic Business Intelligence
US: 1465 Slater Road, PO Box 5007 | Ferndale WA 98248
Canada: 1788 West 5th Ave, Suite 318 | Vancouver BC V6J 1P2
T 800 663 1334 | www.tetrad.com

Re: Accessing Spatial Functionality from Plugin SDK

PaulN — Tue, 17 Jul 2018 16:25:09 GMT

Hey @SigIsaac,

Thank you for the update.

The signature is the following:

(char *) ConvertToGeoJSON(const void *pSpatialObj, unsigned int pLen);

If I am remember correctly, GetAsString() actually calls ConvertToGeoJson when field type is a spatial object.

Thanks,

Paul Noirel (@PaulN)

Sr Customer Support Engineer, Alteryx