Use query function for Naigara4 nHaystack Server

[Makorn-Nupakorn]

Problem

Example Code:

Code 1

• Prompt

from pyhaystack.client.niagara import Niagara4HaystackSession
from pyhaystack.client.http.auth import BasicAuthenticationCredentials
import hszinc

URI  = "server endpoint"
USERNAME  = "username"
PASSWORD  = "password"

authenticator = BasicAuthenticationCredentials(
                                                    USERNAME, 
                                                    PASSWORD
                                                )

json = hszinc.MODE_JSON

session = Niagara4HaystackSession(  
                                            uri = URI,
                                            username = authenticator.username,
                                            password = authenticator.password,
                                            pint = True,
                                            grid_format= json
                                        )

session

• Output

<pyhaystack.client.niagara.Niagara4HaystackSession at 0x12d8aa110>

---

Code 2

• Prompt

session.sites

---

• Output

HaystackError: java.lang.ClassCastException: org.projecthaystack.HStr cannot be cast to org.projecthaystack.HRef

---

Code 3

• Prompt

floor_2 = session.get_entity(
                                ids= "S.Floor_2"
                            )
floor_2.wait()
floor_2.result

• Output

<@S.Floor_2: {area=0.0, axSlotPath='slot:/HS_Ontology/Floor_2', axType='nhaystack:HSite', dis='Floor_2', geoAddr='', geoCity='', geoCoord......, navName='Floor_2', site, tz='Bangkok'}>

---

Question

I can get entity by get_entity function but can not find_entity

• Picture for tagging and ontology

---

• Picture for Resource Unit

---

• Picture for number of entity

[Makorn-Nupakorn]

But if i test on another JACE that have ~900+ points and ~250 equips and 3 sites.

It is well everything I can use every function in pyhaystack.

In this problem case, I test on real site that have ~20 in each modbus device(equip).

I don't know where is error from?

[sjlongland]

Okay, so java.lang.ClassCastException is a server-side exception… caused when you try to cast an object to the wrong sub-class. In this case, it seems to be expecting a HRef and got a HStr instead.

https://github.com/ChristianTremblay/pyhaystack/blob/master/pyhaystack/client/session.py#L405-L420 is pretty simple. So it's doing a find_entity call… unwisely it's not wait()-ing on the result, so this property will only work with the synchronous client (which is default)… but effectively in Haystack-land, it's doing a read?filter="site".

filter= in a read call is supposed to be a HStr, and from what I see in the code, it is a HStr.

If the JACE is expecting something else there, something is seriously wrong. I suspect a bug or misconfiguration in the server.

I'd do the following:

from pyhaystack.exception import HaystackError

try:
    print(session.sites)  # will most likely throw the exception as seen before
except HaystackError as e:
    print(e)
    print(e.traceback)

That'll show you the traceback from the server-side, which you can take up with nHaystack people if needed.

[Makorn-Nupakorn]

I use your script for testing an error

[sjlongland]

Right, so server is suppressing the stack trace (probably a good thing, you don't want to show it to an attacker, nHaystack used to reveal it by default)… but you'll have to look in Niagara Workbench (probably the platform manager if I recall correctly) to see what's going on server-side.