How to get value from JSON list within Robot Framework?

Question

As part of verification in Robot Framework, I have following data (stored as ${response}) as get request response:

{
    "interfaces": [
        {
            "name": "eth0",
            "status": "ready",
            "macAddress": "xx:xx:xx:xx:xx:xx",
            "ipv4": {
                "mode": "DHCP",
                "address": "127.0.0.1",
                "mask": "255.255.255.0",
            },
            "ipv6": {
                "mode": "DISABLED",
                "addresses": [],
                "gateway": "",
            }
        }
    ],
    "result": 0
}

And I would like to get value of key ipv4 and compare it with predefined value. I tried to use it out of HttpLibrary.HTTP as this will be deprecated for Robot Framework 3.1 so I would like to use Evaluate. Will it be possible within Robot Framework?

Solution

If the variable ${response} is a response object - vs just a string, the content of the payload - the most straightforward way is to call its json() method, which returns the payload as parsed dictionary:

${the data}=    Evaluate    ${response.json()}

Another way is to parse the payload with json.loads() yourself, passing the .content attribute that stores it (this is pretty much what the .json() does internally):

${the data}=    Evaluate    json.loads(${response.content})    json

And if that variable ${response} is a string, the actual payload, then just pass it to json.loads():

${the data}=    Evaluate    json.loads($response)    json

Now that you have the data as a regular dictionary, do your verifications the normal way:

Should Be Equal    ${the data['interfaces'][0]['ipv4']}    ${your predefined dictionary}

Comments

[A. Kootstra]

Possible duplicate of Json handling in ROBOT

[Maxx]

I get "No keyword with 'Evaluate ...' found." It seems like everyone who gives an answer about robot framework leaves out the part that would make their answer work.

[Maxx]

Don't answer the question if you're not going to answer the question.

[Todor Minakov]

I'd be very surprised if Evaluate is not recognised, it's a built-in keyword, always available for usage. Are you sure you have 2 or more spaces between it & the 1st argument? If it's just one, the whole string will be parsed as the keyword name & will lead to such exception.