How would you implement scope-based authorization with FastAPI dependencies?

Uses FastAPI Security dependencies to combine declared scopes with current application authorization.

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FastAPI's Security dependency can declare required OAuth2 scopes for a route and expose them through SecurityScopes to the validating dependency. I validate the token first, read its granted scopes, and reject the request when any required scope is missing. The route declares the capability it needs instead of repeating string checks in its body. Resource ownership or tenant access is still checked separately.

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Uses FastAPI Security dependencies to combine declared scopes with current application authorization.

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Uses FastAPI Security dependencies to combine declared scopes with current application authorization.
FastAPI's Security dependency can declare required OAuth2 scopes for a route and expose them through SecurityScopes to the validating dependency. I validate the token first, read its granted scopes, and reject the request when any required scope is missing. The route declares the capability it needs instead of repeating string checks in its body. Resource ownership or tenant access is still checked separately.
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Scopes work well for coarse delegated capabilities such as orders:read or , and they also appear in OpenAPI. I keep a centralized vocabulary and avoid encoding resource ids or every product role into scope names. The dependency returns for invalid authentication and for an authenticated principal lacking access, with the appropriate challenge behavior. Nested dependencies can accumulate required scopes, so I review the complete dependency tree.

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Checking scopes only inside route bodies
Encoding every resource id into a scope
Treating a scope as resource ownership

How would you implement scope-based authorization with FastAPI dependencies?

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