example of how to handle a non-standard payload

[nealwp]

Generally, we might expect a JSON payload that nicely maps to our model, like this:

{
    prop1: "foo",
    prop2: "bar",
    prop3: "baz",
    array1: [thing1, ...],
    array2: [thing1, ...]
}

where we have columns that map to scalar values, and arrays that map to @HasMany(), foreign keys, etc. But what if our incoming payload looked like this, while our model structure stays the same:

{
    mainProp: {
        prop1: "foo",
        prop2: "bar",
        prop3: "baz",
    },
    array1: [thing1, ...],
    array2: [thing1, ...]
}

Add an example model that can deal with this.