I have a few API GETs that I am attempting to use for communication between our machines and an ERP. Using the Postman application I am able to send the GET request and receive a response (Only the names, locations and events have been changed while the structure is still intact):
resultJsonFromAPI.json (2.6 KB)
I plan on most of this information being useful to me in the future but for now this particular API has the "ItemNo" and "UOM" values that I need. I would like to store these values as a tag so I can use them elsewhere. I am able to perform HTTP bindings in Perspective on a TextField and then configure my transform to
{value}[0]["UOM"]
and it returns the expected value. I can also bind the http to a custom property and it will add all the objects in for me:
Unfortunately this does me no good apart from confirming that the API functions and it does seem to be a json.
I am struggling with trying to understand how to script this. I have seen several examples where people have mentioned dictionaries but I don't know what those are or how to make them, and I tried to modify this code but I have obviously butchered the formatting (this snippet is actually from a different API but the info is similar and the concept should be the same):
Header1="ProdOrderNo"
Header2="ProdOrderItemNo"
Header3="ItemNo"
Header4="ItemDesc"
##client = system.net.httpClient() wasnt working like i thought when i did client.get()
response = system.net.httpGet("http://apiroutehere")
data=[]
for key in response.json['ProdOrderComponentItemList']: #i thought this was the name of the primary header. pretty sure im wrong.
data.append([key['ProdOrderNo'],key['ProdOrderItemNo'],key['ItemNo'],key['ItemDesc']])
headers=[Header1,Header2,Header3,Header4]
listing=system.dataset.toDataSet(headers, data)
system.tag.writeAsync(["[default]TagImWritingTo"], [len(data),listing])
I tried to make an expression tag and use jsonGet() but I again could not figure out the headers and I'm not even sure that I was performing the GET correctly. I will only be setting this up once and wont have to do it again (I'm not saying never though) so if I have to manually set up the tags then so be it.
I would greatly appreciate some guidance with where I should even be starting and what the appropriate approach even is. My scripting/Python knowledge is limited, heck I didn't even know what an API was 2 months ago, so thanks for your patience.
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Edit: So I have marked this as solved however I wanted to add some additional information since my API query parameter will change depending on which line I'm currently communicating from. I added two reference tags to obtain this value and keep all my stuff in one place.
I used a Value Changed script event on the relevant tag:
srcTag="pathToTagA"
tarTag="pathToTagB"
srcVal=system.tag.readBlocking(srcTag)[0].value
##allows the parameter for the GET to be dynamic with srcVal as a substitute
addressAPI="APIhttpaddress"+srcVal
response=system.net.httpGet(addressAPI)
system.tag.writeAsync(tarTag,response)
As a result I think the GET only occurs when the value changes (I made an assumption that should reduce the network traffic?) and "tarTag" is a document tag as suggested.
I set up a bunch of expression tags within my UDT that use jsonGet({[.]0jsonFGPalletList},"[0].ProdOrderNo") and substituted [0].ProdOrderNo with the required header. I was having a huge roadblock because I could not wrap my head around how to translate the information from the User Manual example that had clearly defined headers to my data that had none. I don't know how I finally made the connection but I did. I tested this and if the value that is passed as a API query param is not valid it will give Error_ExpressionEval as the result. I am satisfied with how it is setup but would also accept critique. Thanks for all the help.