refactor(gateway): extract from_model classmethods for response models (#925)

## Description

Extracts `from_model` classmethods on `UserResponse`,
`UsageLogResponse`, and `KeyInfo` to centralize ORM-to-Pydantic field
mapping. Replaces 9 copy-pasted construction sites across
`routes/users.py` and `routes/keys.py` with single-line
`Model.from_model(obj)` calls.

Also reuses `KeyInfo.from_model` in `CreateKeyResponse` construction via
`model_dump(exclude={"last_used_at"})` to avoid duplicating the shared
fields.

Net: **-109 lines, +56 lines** — eliminates ~80 lines of duplicated
mapping code.

## PR Type

- 💅 Refactor

## Relevant issues

Fixes #914

## Checklist

- [x] I understand the code I am submitting.
- [x] I have added unit tests that prove my fix/feature works
- [x] I have run this code locally and verified it fixes the issue.
- [x] New and existing tests pass locally
- [x] Documentation was updated where necessary
- [x] I have read and followed the [contribution
guidelines](https://github.com/mozilla-ai/any-llm/blob/main/CONTRIBUTING.md)
- **AI Usage:**
    - [ ] No AI was used.
    - [ ] AI was used for drafting/refactoring.
    - [x] This is fully AI-generated.

## AI Usage Information

- AI Model used: Claude Opus 4.6
- AI Developer Tool used: Claude Code

- [x] I am an AI Agent filling out this form (check box if true)

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: njbrake

src/any_llm/gateway/routes/keys.py

@@ -46,6 +46,19 @@ class KeyInfo(BaseModel):
     is_active: bool
     metadata: dict[str, Any]
 
+    @classmethod
+    def from_model(cls, key: APIKey) -> "KeyInfo":
+        return cls(
+            id=str(key.id),
+            key_name=str(key.key_name) if key.key_name else None,
+            user_id=str(key.user_id) if key.user_id else None,
+            created_at=key.created_at.isoformat(),
+            last_used_at=key.last_used_at.isoformat() if key.last_used_at else None,
+            expires_at=key.expires_at.isoformat() if key.expires_at else None,
+            is_active=bool(key.is_active),
+            metadata=dict(key.metadata_) if key.metadata_ else {},
+        )
+
 
 class UpdateKeyRequest(BaseModel):
     """Request model for updating a key."""
@@ -107,15 +120,10 @@ async def create_key(
     db.commit()
     db.refresh(db_key)
 
+    key_info = KeyInfo.from_model(db_key)
     return CreateKeyResponse(
-        id=str(db_key.id),
+        **key_info.model_dump(exclude={"last_used_at"}),
         key=api_key,
-        key_name=str(db_key.key_name) if db_key.key_name else None,
-        user_id=str(db_key.user_id) if db_key.user_id else None,
-        created_at=db_key.created_at.isoformat(),
-        expires_at=db_key.expires_at.isoformat() if db_key.expires_at else None,
-        is_active=bool(db_key.is_active),
-        metadata=dict(db_key.metadata_) if db_key.metadata_ else {},
     )
 
 
@@ -131,19 +139,7 @@ async def list_keys(
     """
     keys = db.query(APIKey).offset(skip).limit(limit).all()
 
-    return [
-        KeyInfo(
-            id=str(key.id),
-            key_name=str(key.key_name) if key.key_name else None,
-            user_id=str(key.user_id) if key.user_id else None,
-            created_at=key.created_at.isoformat(),
-            last_used_at=key.last_used_at.isoformat() if key.last_used_at else None,
-            expires_at=key.expires_at.isoformat() if key.expires_at else None,
-            is_active=bool(key.is_active),
-            metadata=dict(key.metadata_) if key.metadata_ else {},
-        )
-        for key in keys
-    ]
+    return [KeyInfo.from_model(key) for key in keys]
 
 
 @router.get("/{key_id}", dependencies=[Depends(verify_master_key)])
@@ -163,16 +159,7 @@ async def get_key(
             detail=f"API key with id '{key_id}' not found",
         )
 
-    return KeyInfo(
-        id=str(key.id),
-        key_name=str(key.key_name) if key.key_name else None,
-        user_id=str(key.user_id) if key.user_id else None,
-        created_at=key.created_at.isoformat(),
-        last_used_at=key.last_used_at.isoformat() if key.last_used_at else None,
-        expires_at=key.expires_at.isoformat() if key.expires_at else None,
-        is_active=bool(key.is_active),
-        metadata=dict(key.metadata_) if key.metadata_ else {},
-    )
+    return KeyInfo.from_model(key)
 
 
 @router.patch("/{key_id}", dependencies=[Depends(verify_master_key)])
@@ -205,16 +192,7 @@ async def update_key(
     db.commit()
     db.refresh(key)
 
-    return KeyInfo(
-        id=str(key.id),
-        key_name=str(key.key_name) if key.key_name else None,
-        user_id=str(key.user_id) if key.user_id else None,
-        created_at=key.created_at.isoformat(),
-        last_used_at=key.last_used_at.isoformat() if key.last_used_at else None,
-        expires_at=key.expires_at.isoformat() if key.expires_at else None,
-        is_active=bool(key.is_active),
-        metadata=dict(key.metadata_) if key.metadata_ else {},
-    )
+    return KeyInfo.from_model(key)
 
 
 @router.delete("/{key_id}", status_code=status.HTTP_204_NO_CONTENT, dependencies=[Depends(verify_master_key)])

src/any_llm/gateway/routes/users.py

@@ -36,6 +36,21 @@ class UserResponse(BaseModel):
     updated_at: str
     metadata: dict[str, Any]
 
+    @classmethod
+    def from_model(cls, user: User) -> "UserResponse":
+        return cls(
+            user_id=user.user_id,
+            alias=user.alias,
+            spend=float(user.spend),
+            budget_id=user.budget_id,
+            budget_started_at=user.budget_started_at.isoformat() if user.budget_started_at else None,
+            next_budget_reset_at=user.next_budget_reset_at.isoformat() if user.next_budget_reset_at else None,
+            blocked=bool(user.blocked),
+            created_at=user.created_at.isoformat(),
+            updated_at=user.updated_at.isoformat(),
+            metadata=dict(user.metadata_) if user.metadata_ else {},
+        )
+
 
 class UpdateUserRequest(BaseModel):
     """Request model for updating a user."""
@@ -63,6 +78,24 @@ class UsageLogResponse(BaseModel):
     status: str
     error_message: str | None
 
+    @classmethod
+    def from_model(cls, log: UsageLog) -> "UsageLogResponse":
+        return cls(
+            id=log.id,
+            user_id=log.user_id,
+            api_key_id=log.api_key_id,
+            timestamp=log.timestamp.isoformat(),
+            model=log.model,
+            provider=log.provider,
+            endpoint=log.endpoint,
+            prompt_tokens=log.prompt_tokens,
+            completion_tokens=log.completion_tokens,
+            total_tokens=log.total_tokens,
+            cost=log.cost,
+            status=log.status,
+            error_message=log.error_message,
+        )
+
 
 @router.post("", dependencies=[Depends(verify_master_key)])
 async def create_user(
@@ -113,18 +146,7 @@ async def create_user(
     db.commit()
     db.refresh(user)
 
-    return UserResponse(
-        user_id=user.user_id,
-        alias=user.alias,
-        spend=float(user.spend),
-        budget_id=user.budget_id,
-        budget_started_at=user.budget_started_at.isoformat() if user.budget_started_at else None,
-        next_budget_reset_at=user.next_budget_reset_at.isoformat() if user.next_budget_reset_at else None,
-        blocked=bool(user.blocked),
-        created_at=user.created_at.isoformat(),
-        updated_at=user.updated_at.isoformat(),
-        metadata=dict(user.metadata_) if user.metadata_ else {},
-    )
+    return UserResponse.from_model(user)
 
 
 @router.get("", dependencies=[Depends(verify_master_key)])
@@ -136,21 +158,7 @@ async def list_users(
     """List all users with pagination."""
     users = db.query(User).filter(User.deleted_at.is_(None)).offset(skip).limit(limit).all()
 
-    return [
-        UserResponse(
-            user_id=user.user_id,
-            alias=user.alias,
-            spend=float(user.spend),
-            budget_id=user.budget_id,
-            budget_started_at=user.budget_started_at.isoformat() if user.budget_started_at else None,
-            next_budget_reset_at=user.next_budget_reset_at.isoformat() if user.next_budget_reset_at else None,
-            blocked=bool(user.blocked),
-            created_at=user.created_at.isoformat(),
-            updated_at=user.updated_at.isoformat(),
-            metadata=dict(user.metadata_) if user.metadata_ else {},
-        )
-        for user in users
-    ]
+    return [UserResponse.from_model(user) for user in users]
 
 
 @router.get("/{user_id}", dependencies=[Depends(verify_master_key)])
@@ -167,18 +175,7 @@ async def get_user(
             detail=f"User with id '{user_id}' not found",
         )
 
-    return UserResponse(
-        user_id=user.user_id,
-        alias=user.alias,
-        spend=float(user.spend),
-        budget_id=user.budget_id,
-        budget_started_at=user.budget_started_at.isoformat() if user.budget_started_at else None,
-        next_budget_reset_at=user.next_budget_reset_at.isoformat() if user.next_budget_reset_at else None,
-        blocked=bool(user.blocked),
-        created_at=user.created_at.isoformat(),
-        updated_at=user.updated_at.isoformat(),
-        metadata=dict(user.metadata_) if user.metadata_ else {},
-    )
+    return UserResponse.from_model(user)
 
 
 @router.patch("/{user_id}", dependencies=[Depends(verify_master_key)])
@@ -221,18 +218,7 @@ async def update_user(
     db.commit()
     db.refresh(user)
 
-    return UserResponse(
-        user_id=user.user_id,
-        alias=user.alias,
-        spend=float(user.spend),
-        budget_id=user.budget_id,
-        budget_started_at=user.budget_started_at.isoformat() if user.budget_started_at else None,
-        next_budget_reset_at=user.next_budget_reset_at.isoformat() if user.next_budget_reset_at else None,
-        blocked=bool(user.blocked),
-        created_at=user.created_at.isoformat(),
-        updated_at=user.updated_at.isoformat(),
-        metadata=dict(user.metadata_) if user.metadata_ else {},
-    )
+    return UserResponse.from_model(user)
 
 
 @router.delete("/{user_id}", status_code=status.HTTP_204_NO_CONTENT, dependencies=[Depends(verify_master_key)])
@@ -278,21 +264,4 @@ async def get_user_usage(
         .all()
     )
 
-    return [
-        UsageLogResponse(
-            id=log.id,
-            user_id=log.user_id,
-            api_key_id=log.api_key_id,
-            timestamp=log.timestamp.isoformat(),
-            model=log.model,
-            provider=log.provider,
-            endpoint=log.endpoint,
-            prompt_tokens=log.prompt_tokens,
-            completion_tokens=log.completion_tokens,
-            total_tokens=log.total_tokens,
-            cost=log.cost,
-            status=log.status,
-            error_message=log.error_message,
-        )
-        for log in usage_logs
-    ]
+    return [UsageLogResponse.from_model(log) for log in usage_logs]