Refactor model call query params

[juandjara]

Following up on the conversation here: #34 (comment) I've created this PR with a refactor proposal of this internal part, to reduce the amount of type casting

[donmccurdy]

Much cleaner than we originally had, thank you!

[donmccurdy]

Minor – Let's use isPureObject from utils, instead of the typeof check here. Probably doesn't matter, but this way "null" falls through to the next case and we can do a null or undefined check.

[juandjara]

And will the isPureObject check catch arrays too?
Right now, checking for object types we are stringifying object and arrays, and converting null to "null".

However, we could separate these three cases in three conditionals to make it easier to read

[juandjara]

It would read as something like this

if (isPureObject(object[key])) {
  params.append(key, JSON.stringify(object[key]));
}
else if (Array.isArray(object[key])) {
  params.append(key, JSON.stringify(object[key]));
}
else if (object[key] === null) {
  params.append(key, 'null');
}
else if (object[key] !== undefined) {
  params.append(key, String(object[key]));
}

[juandjara]

Something Im not sure about is how we want to treat null values here