March 28, 2023

Any developer who has used Doctrine query caching to improve the performance of queries may have run into an “Invalid parameter number” error when trying to execute queries that use an “IN ?” clause. This issue can be caused by a few different factors, all of which can be traced back to a common source.

At the core of the issue is the fact that Doctrine query caching utilizes a certain format for storing and retrieving query related information, and this format may not always be able to handle IN clauses. Because of this, when caching is enabled, some queries with IN clauses will receive this error when being executed.

Fortunately, there are a few possible solutions to this issue. The first and most obvious is to simply disable cache in areas where IN clauses are being used. Caching can easily be disabled on a line-by-line basis in the code, allowing only specific queries to remain cached and still understand the IN parameter.

The second solution is to use eager fetching for any queries using IN clauses. This allows the query to bypass internal caching and should eliminate any related errors. However, eager fetching can also cause other issues if not used carefully, so this solution should only be employed after careful consideration has been given.

Finally, if neither of these two solutions can be implemented for whatever reason, it may be beneficial to implement custom caching rules for any queries using an IN clause. This allows greater control over how queries are cached, reducing the likelihood of this error occurring again in the future.

For many web applications, Doctrine is the open-source ORM (Object-Relational Mapping) of choice. Developers who use it to create their project’s persistence layer know that it comes with some helpful query caching options, including query result caching and query DQL caching. Unfortunately, however, it appears these features combined can lead to an “Invalid parameter number” error when using “IN ?” queries.

Although developers often find the error message infuriatingly unhelpful, this clue provides an indication of what’s happening at a technical level. It means that the number of parameters in the query is greater than the number of values in the array parameter being passed to the prepared statement. When using queries with IN ? expressions with Doctrine and query caching on, this error can occur because Doctrine will cache each combination of different-length variable parameters and re-use them without checking if they still apply. In other words, if a variable array parameter is longer than the number of parameters in the original query, then it will crash when executed a second time attempting to match together more parameters than the cached version contained.

The good news is that there are two potential solutions for this issue. If your application doesn’t need result caching at all or if you’re confident you won’t be sending variable array parameters of different lengths to the same query, then you can easily turn off query result caching entirely by making a configuration change. On the other hand, you may find yourself unable to switch off result caching entirely but still want to leverage query caching safely. If that’s the case, then take a look at the Doctrine documentation which explains how to set up parameterYieldMap, which allows you to manually make sure compatible parameters are used when running multiple versions of the same query.

Whether you’re new to Doctrine or have used it successfully in your projects for years, it’s important to remember that even a seemingly simple issue can have a complex resolution. In this case, doctrine query caching can cause “Invalid parameter number” errors for queries that use “IN ?”. Fortunately there are solutions available if you know where to look — so make sure you check out both your configuration options and parameterYieldMap before giving up on finding a solution!