Python Error when referencing yang variable with multiple keys

[BasharAziz]

Hi All, 

I am trying to reference an xpath of service A in service B. In service B will first lookup for devicename(key) and prefix id(key)

the third key is static [public='true']:

Service A:

/services/test:test[devicename='ww']/prefixes[prefix='6000'][public='true']/ipv4Address 200.1.1.1
/services/test:test[devicename='ww']/prefixes[prefix='6000'][public='false']/ipv4Address 172.1.1.1

Service B:

vars.add('ipv4Address', f'{root.services.devicename[service.Service_B_devicename].prefixes[service.prefix][public == "true"].ipv4Address}')

template.apply('netaccessevc-prefix-ipv4-template', vars)

 I am getting this error:

errors: reason: Python cb_create error. badly formatted or nonexistent path (8): Bad key "6000" (wrong number of identifiers) at: /services/test/prefixes

[vleijon · Accepted solution]

The syntax for multi-key lists in the python api is [(key1, key2)]. So slightly different from xpath.

[baziz1]

prefixes Is a list with two keys: prefix and public.

prefix is will be selected in service B, while public is always true. 

[gmuloche · Accepted solution]

Hello,

Looks like you are trying to get the value of the leaf

root.services.devicename["ww"].prefixes[6000,"true"].ipv4Address 

 inside the variable for your templates.

Couple of points here:

* As @vleijon mentioned the correct way to reference the leaf should use the python syntax for multi key list (you can look it up there: https://developer.cisco.com/docs/nso/guides/#!python-api-overview/maagic-api - subsection List and List Elements - there is no anchor at this hierarchy level so cannot point you to it directly)

* You actually don't need the f string

From what I understand from your model, a possible resolution in service B would be:

vars.add('ipv4Address', root.services.devicename[service.Service_B_devicename].prefixes[service.prefix,"true"].ipv4Address)

which *SHOULD* put the value of the leaf ipv4Address for (6000, "true") inside the variable you are then using in your template.