How to Read JSON from LabVIEW Web Service HTTP VIs

[Anthony_L]

I am using this article to submit Web Server JSON Web Service response as 2D array.

However, the LabVIEW Web Service client gets an empty curly bracket {} result.

The article is here:

How to Send a Response as JSON Format From LabVIEW Web Service - NI

PNG of my Web Server VI and Web Service Client are attached. There is also a screen shot of Header and Body response.

Is there anything that I am doing wrong?

[rolfk]

The obvious question would be if the SQL query actually returns any data or just an empty array?

[Anthony_L]

• Here is the data returned by the SQL Query VI. See attached PNGs
• The data shown is already converted to JSON as per block diagram indicator.
• That data comes up as just  { } on the Web service client VI.

If I use a STRING indicator for result, and place it on the connector pane, I do get all the data but the format is messed up with ESCAPE characters and such.

Anthony

[Anthony_L]

Spoiler

Attached is the LabVIEW web service project files.

1. The Web Service Project
2. HTTP LabVIEW Client to access that Web Service

I see this error coming from the WRITE RESPONSE VI:

NI_WebServices.lvlib:Error Converter (ErrCode or Status).vi<APPEND>

[Anthony_L · Accepted solution]

OK, that error is now resolved!

The reason why it was happening was because, if you send anything via the WRITE RESPONSE Web Service VI as an output, you MUST set the METHOD VI Property to STREAM.

See setting in attached PNG.