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All BackAnt routes return JSON using Flask’s jsonify() function.

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Basic JSON response

from flask import jsonify

@users_bp.get("")
def get_users():
    response = myUsersService.get_users()
    return jsonify(response)
jsonify() accepts dicts, lists, strings, numbers, booleans, and None. It sets the Content-Type header to application/json automatically.

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Returning SQLAlchemy models

SQLAlchemy models in BackAnt are @dataclass classes, which means they serialize to dicts automatically when passed to jsonify(): 
@dataclass
class Users(Base):
    __tablename__ = "users"
    id: int = Column(Integer, primary_key=True)
    name: str = Column(String)

user = myUsersRepository.get_by_id(1)
return jsonify(user)
# {"id": 1, "name": "Alice"}
For lists of models: 
users = myUsersRepository.get_all_users()
return jsonify(users)
# [{"id": 1, "name": "Alice"}, {"id": 2, "name": "Bob"}]

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HTTP status codes

Pass the status code as the second return value: 
return jsonify(response), 200   # OK (default)
return jsonify(response), 201   # Created
return jsonify({}), 204         # No Content
return jsonify(response), 400   # Bad Request
return jsonify(response), 404   # Not Found

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Error responses

Do not construct error responses manually in routes. Raise APIException from the service layer and the registered error handler in app.py converts it to JSON automatically: 
# In the service:
raise APIException(status_code=404, message="User not found")

# Automatically becomes:
# HTTP 404
# {"message": "User not found"}
See Error Handling for the full APIException API.

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Adding response headers

response = jsonify(data)
response.headers["X-Total-Count"] = str(total)
return response

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Returning empty responses

For DELETE endpoints that return no body: 
return jsonify({}), 204
Or with a confirmation message: 
return jsonify({"deleted": True, "id": user_id}), 200