User can create routing regular expression without pattern param input

[dpham692]

I'm submitting a ...

• bug report

Traffic Control components affected ...

• Traffic Ops

Current behavior:

The POST handler of the deliveryservices/{{ID}}/regexes endpoint let user create routing regular expression for a Delivery Service when the request payload have a blank pattern.

Expected / new behavior:

It should not let user create regexes and return 400 Bad Request with response message like

{
    "alerts": [
        {
            "text": "malformed JSON",
            "level": "error"
        }
    ]
}

Minimal reproduction of the problem with instructions:

Do a POST https://{{TO_BASE_URL}}/api/3.0/deliveryservices/1/regexes with this payload:

{
    "pattern": "",
    "type": 33,
    "setNumber": 20
}

Pattern input is empty and user can still create a regrexes.

Anything else:

[mitchell852]

@dpham692 - just curious. can you do a blank pattern in TP?

[rimashah25]

@mitchell852: No, TP has it as a required field.