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How to replace Extra.forbid with extra='forbid' in Pydantic v2

Migrate the Extra enum usage to string literal in model_config.

Start here

The safe first move

Replace Extra.forbid (and Extra.allow, Extra.ignore) with the string literal 'forbid', 'allow', or 'ignore' in model_config.

Stop before automation when: Dynamic extra config based on runtime logic. Files with other unsupported Config keys.

Target shape

from pydantic import BaseModel, ConfigDict

class Strict(BaseModel):
    model_config = ConfigDict(extra="forbid")

Repo fit check

Want to know if your repo has this pattern?

Run the matching scanner locally first. Read the free findings and manual alternatives; consider paid cleanup only if supported patterns repeat enough to justify the price.

  • Local scan; no repository upload.
  • Supported findings are separated from manual-review findings.
  • Buy only when the repeated pattern is worth automating.
Run the Pydantic scan first View example report See when to buy 
Example scan summary
supported_findings: 38
manual_review_findings: 6
files_uploaded: 0
confidence: reviewable

Why this page exists

How to replace Extra.forbid with extra='forbid' in Pydantic v2

The Extra enum is gone. Use string literals in model_config.

Direct answer

What changes

Replace Extra.forbid (and Extra.allow, Extra.ignore) with the string literal 'forbid', 'allow', or 'ignore' in model_config.

Example

Before and after

Before

from pydantic import BaseModel, Extra

class Strict(BaseModel):
    class Config:
        extra = Extra.forbid

After

from pydantic import BaseModel, ConfigDict

class Strict(BaseModel):
    model_config = ConfigDict(extra="forbid")

Decision path

If this repeats across the repo, open the evaluation pages next.

The cleanup pack is strongest when the repo still uses direct pydantic imports and a clean validator/settings/config subset.

  • The repo has direct pydantic or pydantic.v1 imports, BaseSettings usage, safe Config blocks, or simple validators.
  • The migration pain is repetitive v1-to-v2 cleanup, not a custom semantic rewrite.
  • If the scan output is ambiguous, review its findings and upstream guidance. Do not buy expecting unsupported cases to be resolved.

Typical symptoms

  • ImportError for Extra from pydantic.
  • Models still reference Extra.forbid in nested Config.
  • Teams want the Extra cleanup bundled with Config migration.

What the product covers

  • Extra.forbid/allow/ignore to string literal rewrites.
  • Nested Config to model_config conversion.
  • Cross-links to the Config migration page.

Manual-review boundary

  • Dynamic extra config based on runtime logic.
  • Files with other unsupported Config keys.
  • Alias imports of Extra.

Keep the migration narrow

Use the exact-problem guides as a triage layer, then decide whether the repo is inside the supported subset.

FAQ

Fast answers before you decide

What is the safest fix for Extra.forbid pydantic v2?

Replace Extra.forbid (and Extra.allow, Extra.ignore) with the string literal 'forbid', 'allow', or 'ignore' in model_config.

Can Extra.forbid pydantic v2 be automated?

Automate only the supported subset: Extra.forbid/allow/ignore to string literal rewrites. Nested Config to model_config conversion. Cross-links to the Config migration page. Keep these cases in manual review: Dynamic extra config based on runtime logic. Files with other unsupported Config keys. Alias imports of Extra.

When should I buy Pydantic v1 to v2 Migration Cleanup Pack?

Use Pydantic v1 to v2 Migration Cleanup Pack only when this pattern repeats across enough files that manual cleanup is still costly. Use the free report and upstream guide to evaluate fit. Buy only if repeated supported edits justify the price; no paid assessment is required.

Purchase fit

Choose the lowest-risk next step.

One matching page is not enough by itself. Run the local scan, then buy only when the same supported pattern appears often enough to matter.

Buy if

  • The repo has direct pydantic or pydantic.v1 imports, BaseSettings usage, safe Config blocks, or simple validators.
  • The migration pain is repetitive v1-to-v2 cleanup, not a custom semantic rewrite.
  • The team accepts manual-review findings for alias-heavy imports and signature-heavy validators.

What the workflow includes

  • Installable local CLI workflow, not a hosted black box.
  • Supported validator, settings, import, and config rewrites.
  • Demo report, public proof, coverage notes, rollback checklist, and buyer terms.

Before checkout

  • Stripe Checkout handles secure payment and receipts.
  • Download your purchased ZIP after payment.
  • Runs locally; no hosted API, repo upload, or production credentials needed.
  • The free report includes the evidence needed to evaluate fit. Paid summary and template add-ons are optional.
  • 14-day refund review for published-scope or delivery mismatches.
Run the Pydantic scan first

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