DBAL-1156: Doctrine assumes that PDO is available

[doctrinebot]

Jira issue originally created by user azielinski:

use PDO and references to PDO class are seen in following files:
Connection.php
Statement.php
Cache/ArrayStatement.php
Cache/ResultCacheStatement.php
Driver/PDOConnection.php
Driver/Mysqli/MysqliStatement.php
Driver/OCI8/OCI8Statement.php
Driver/SQLSrv/SQLSrvStatement.php
Driver/Portability/Statement.php

It's all about using constants like PDO::FETCH_COLUMN. No actual methods are invoked, no objects are instantiated. This could be easily abstracted out to a class included in doctrine-dbal.

I stumbled upon this because I tried to use mysqli driver specifically because my installation of PHP is compiled with --disable-pdo.

As a quick & dirty workaround I included a file PDO.php with a shim, but it would be nice if Doctrine did not assume PDO is installed.

I am more than happy to prepare a pull request to fix it if you confirm this is something that needs attention.

[doctrinebot]

Comment created by @Ocramius:

Seems rather like a missing dependency in composer.json to me: we rely on PDO's APIs, and we're not really interested in polyfilling it when it's not available, as it's actually a lot of code to write for a little achievement :-\

[doctrinebot]

Comment created by azielinski:

Why provide non-PDO drivers then? In doctrine-dbal not a single method or object from PDO is used (aside of PDOConnection.php), it's all about accessing constants like PDO::PARAM_STR. This particular thing could be polyfilled very easily.

[doctrinebot]

Comment created by @Ocramius:

Those drivers work as long as PDO is also installed.

[doctrinebot]

Comment created by azielinski:

Sure they do, my point is that with minimal effort (that I offer to provide) those drivers could work without PDO as well. In fact that would make more sense - I can imagine that one of typical use cases for e.g. Mysqli driver is a situation where PDO cannot be used for some reason.

Correct me if I'm wrong, but I believe there is no real reason for doctrine-dbal to depend on PDO. Aside of accessing constants, PDO is only used by PDOConnection (which is only used by PDO-based drivers). PDO constants can be shimmed extremely easily.

[doctrinebot]

Comment created by @Ocramius:

[~azielinski] if that's the minimal requirement, then a shim is fine

[chrisguitarguy]

Seems rather like a missing dependency in composer.json to me

I suspect this one can be closed as composer.json requires PDO explicitly now.

[lcobucci]

@chrisguitarguy thanks!

[lcobucci]

Fixed in #2709

[morozov]

This is a thing I still don't understand about the DBAL: as a user, why in order to use oci8 or ibm_db2 I should also install PDO? I understand that for some reason the DBAL it uses its contstants as part of its API but it looks like a design issue.

Would the community consider a patch which replaces the usage of PDO constants with its own ones?

[lcobucci]

@morozov we had that discussion already, right? maybe we can review this for v3.0?

[morozov]

@lcobucci #808 (comment) is the only discussion I'm aware of. The patch wasn't about fixing the real issue. v3.0 sounds reasonable to me.

[github-actions]

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