[8.x] Add castAsJson method for database assertions

[browner12]

database fields of type 'json' cannot be evaluated using strings, they must be cast to a database specific JSON type.

$this->assertDatabaseHas('users', [
    'name' => 'Peter Parker',
    'email' => 'spidey@yahoo.com',
    'skills' => $this->castAsJson(json_encode(['web slinging', 'spidey-sense', 'sticky feet'])),
]);

[taylorotwell]

It feels like this should be more automatic maybe?

[browner12]

that would be nice, but I'm not sure that would be reasonably possible. you'd have to know/query the field type prior.

even if you had the Model, you couldn't base it off that, because some people use the 'json' cast, but still use a 'longtext' or similar as the database type, and we don't need to do this for those field types.

If you have a thought on how to accomplish this, I'm definitely open to it.

[laurencei]

If you are calling the function castAsJson - why do you need to call json_encode for the string you are passing it?

i.e.

- $this->castAsJson(json_encode(['web slinging', 'spidey-sense', 'sticky feet'])),
+ $this->castAsJson(['web slinging', 'spidey-sense', 'sticky feet']),

And then have the function do the json_encoding() itself?

[browner12]

PHP JSON encoding is different than database type casting.

I'm passing in an array, so first that needs to be encoded as a string, and then that string needs to be cast to JSON in the database query.

[laurencei]

Sorry - I was not very clear - I meant then do the json_encoding in the other function. Something like this:

    public function castAsJson($value)
    {
+        $value = json_encode($value);
         return DB::raw("CAST('$value' AS JSON)");
    }

[browner12]

Ah, I see. I go back and forth on if that's the responsibility of this method. I'm not sure if there'd be a scenario where someone already has a value as JSON, so then they would need to decode it prior to passing it to the function, so it doesn't get double encoded.

Honestly, I could go either way on this, so would be open to hearing other people's opinions.

[halloei]

What's still missing here is escaping. $this->castAsJson(['\Some\Class']) will fail.
I am using the solution of talentia, which you can find in this answer: https://laracasts.com/discuss/channels/testing/how-to-assert-that-the-database-contains-a-value-stored-as-json?page=1#reply=416476
Here, addslashes() and null checks are used.

[vlakoff]

Refs #37619