Validation Groups vs. Serialization Groups
Validation Groups vs. Serialization Groups
~12 Min. Lesezeit Zuletzt aktualisiert am August 8, 2026
Two SIMILAR-sounding but COMPLETELY different concepts become important from here on – this short chapter creates conceptual clarity BEFORE the next ones (serialization, chapters 23-26).
Validation groups: WHICH constraints apply when
EXACTLY as in the Symfony course (chapter 24), validation groups allow checking constraints ONLY in certain situations, e.g. a password field ONLY during registration, NOT when editing an existing user:
#[Assert\NotBlank(groups: ['registration'])]
private ?string $plainPassword = null;Serialization groups: WHICH fields are visible
Serialization groups (chapter 23), by contrast, control WHICH properties even APPEAR in the JSON – an internalNotes field could, for instance, be visible ONLY to admin users, completely ABSENT for everyone else.
| Concept | Effect |
|---|---|
| Validation group | Controls WHETHER a constraint gets checked – applies ONLY to writing (POST/PUT/PATCH) |
| Serialization group | Controls WHETHER a field appears in the JSON – applies to READING (GET) AND writing (which fields get accepted) |
Achtung: The MOST COMMON beginner mistake: HIDING a field via a serialization group, assuming it's thereby ALSO protected from being WRITTEN – serialization groups affect VISIBILITY, NOT automatically WRITABILITY. For REAL write protection, additional access controls are needed (security attribute, block 6).
Both concepts combined
In practice, BOTH are used together: a project:write serialization group determines which fields a POST request ACCEPTS, while a validation group additionally controls WHICH constraints apply to those accepted fields.
Tipp: When in doubt, this mnemonic helps: validation asks "Is the value VALID?", serialization asks "Should the field be visible/acceptable AT ALL?" – TWO FUNDAMENTALLY DIFFERENT questions.