Field SQL storage does not correctly detect value changes with leading zeros

Created on 13 September 2021, about 3 years ago

Updated 16 April 2024, 7 months ago

Problem/Motivation

When the config field_sql_storage_skip_writing_unchanged_fields is enabled and a fieldable enttiy is saved, the field SQL storage will perform a check to see if any field values have changed. If it detects that nothing was changed, the SQL write query is skipped. This comparison is done in _field_sql_storage_write_compare(). Currently, there is a bug in this function due to PHP's type juggling when using == or (in this case) !=: In PHP, '01' == '001' is TRUE.
However, when updating a field value, one may need to specify leading zeroes. Changes to that field value should not be omitted just because of PHP's type juggling.

The same bug seems to be active in Drupal 8 & 9 at the moment, see this issue → .

Steps to reproduce

Have an entity (e.g. node) with a field (e.g. textfield).
Add an field value containing only numbers, e.g. 0012.
Save the entity; everything should work as expected.
Edit the entity again, prepend one or more zeros the previously added value (e.g. updating it to 00012), and save again.
Inspect the field value: it'll still be 0012 instead of the exacted 00012.

Proposed resolution

Recursively check nested arrays, use `===` for non-array values.

🐛 Bug report

Status

Needs work

Version

7.0 ⚰️

Component

Field →

Last updated about 13 hours ago

Maintained by
🇷🇴Romania @amateescu

Created by

🇦🇹Austria Bird-Kid

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Field SQL Storage

Needs tests
The change is currently missing an automated test that fails when run with the original code, and succeeds when the bug has been fixed.

Incomplete comments

Comments & Activities

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It's likely this issue predates Contrib.social: some issue and comment data are missing.

Comment 8 months ago →
🇸🇪Sweden kristofferwiklund
Fixes our problem with resaving 001. This fix also fixed problem with float values stored in string field. So that 0.01 => 0.0100 is saved.
Comment 7 months ago →
🇮🇹Italy apaderno Brescia, 🇮🇹
The patch still applies to the 7.x branch.
Status changed to Needs work 7 months ago6:12pm 16 April 2024
Comment 7 months ago →
🇸🇰Slovakia poker10
Thanks for reporting and working on this! It is a really unpleasent bug.

The D7 version of the array compare function is a bit different from the latest D9/10 patch here: #2925972: FieldItemList::equals() doesn't correctly compare textfield values with leading zeros → . I think we need to check if we are not missing any other possible conditions present in the D9 patch. Other than that, we need to add tests for this. So moving to Needs work. Thanks!

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