Laravel Invalid Parameter Number with whereIn()

I’m posting this so that I remember in a few years when this happens again…

We had a very interesting error that simply said- SQLSTATE[HY093]: Invalid parameter number. The query that it showed looked fine and so I spent a significant amount of time scratching my head wondering if I was losing my marbles.

Here was the query-

select * from posts where uuid in (random-uuid-here)

Looks fine right? Well turns out we were passing an array of an array into this whereIn- something that looked similar to this-

[
  [
    'uuid_1',
    'uuid_2',
    'uuid_3',
  ]
]

And this generated a query that looked like this-

select * from posts where uuid in (?)

It was attempting to bind each uuid to that one parameter so it gave the invalid parameter number error. What we needed was something closer to this-

select * from posts where uuid in (?, ?, ?)

The solution was to flatten the array down to a single depth so whereIn would know to bind the correct number of parameters.

Future me- if you ever read this, make sure you pass flat arrays into whereIn. Pretty please?