Craft 3 plugin - how to update entry with field of Entries type

Question

Using PHP, I want to update a field of Entries type of an existing entry.

Fields of type Text and Number will update with the following code:

$entry = Entry::find()->id($entryId)->one();
$entry->textField = 20; // works
$entry->entriesField = Entry::find()->id($relatedEntryIds)->all(); // doesn't work
Craft::$app->elements->saveElement($entry);

I looked into the source code and it seems to be expecting a craft\elements\db\EntryQuery object but I can't get it to work.

Can anyone please help?

Answer 1

Ok this was easy. Tried it at first but didn't work and was successful after another go. All it needed was a array of Entry IDs.

Working code:

$entry = Entry::find()->id($entryId)->one();
$entry->textField = 20; // works
$entry->entriesField = [$relatedEntryId1, $relatedEntryId2]; // works
Craft::$app->elements->saveElement($entry);

Answer 2

As per the docs at https://craftcms.com/docs/3.x/extend/element-types.html#saving-custom-field-values

When saving values on a custom field, always use the setFieldValue() or setFieldValues() methods rather than directly accessing the field handle as a property on the element object. This ensures the value is normalized and marked as dirty for delta saves.

$entry->setFieldValue('testField', 'foo');
$entry->setFieldValue('entriesField', [$relatedEntryId1, relatedEntryId2]);

Craft::$app->elements->saveElement($entry);