Se genera cuando se intenta establecer un valor o borrar una propiedad calculada.
exceptionInvalidPropertyError()
Se genera cuando una propiedad no es aplicable a determinado uso. Por ejemplo, una propiedad debe existir y estar indexada para utilizarse en la proyección de una consulta o en una cláusula por grupo.
exceptionReadonlyPropertyError()
Se genera cuando se intenta establecer un valor de propiedad que es de solo lectura.
exceptionUnprojectedPropertyError()
Se genera cuando se obtiene un valor de propiedad que no está en la proyección.
[[["Fácil de comprender","easyToUnderstand","thumb-up"],["Resolvió mi problema","solvedMyProblem","thumb-up"],["Otro","otherUp","thumb-up"]],[["Difícil de entender","hardToUnderstand","thumb-down"],["Información o código de muestra incorrectos","incorrectInformationOrSampleCode","thumb-down"],["Faltan la información o los ejemplos que necesito","missingTheInformationSamplesINeed","thumb-down"],["Problema de traducción","translationIssue","thumb-down"],["Otro","otherDown","thumb-down"]],["Última actualización: 2025-09-04 (UTC)"],[[["\u003cp\u003eThis page explains the usage of legacy bundled services and APIs, which are exclusive to first-generation runtimes in the App Engine standard environment.\u003c/p\u003e\n"],["\u003cp\u003eA migration guide is available for those updating to the App Engine Python 3 runtime, offering options for migrating legacy bundled services.\u003c/p\u003e\n"],["\u003cp\u003eThe NDB datastore offers several unique exception classes, including \u003ccode\u003eComputedPropertyError\u003c/code\u003e, \u003ccode\u003eInvalidPropertyError\u003c/code\u003e, \u003ccode\u003eReadonlyPropertyError\u003c/code\u003e, and \u003ccode\u003eUnprojectedPropertyError\u003c/code\u003e.\u003c/p\u003e\n"],["\u003cp\u003eThese exceptions deal with scenarios like attempting to set or delete a computed property, improper usage of a property, setting a read-only property, or accessing an unprojected property.\u003c/p\u003e\n"]]],[],null,["# Exceptions\n\n| This page describes how to use the legacy bundled services and APIs. This API can only run in first-generation runtimes in the App Engine standard environment. If you are updating to the App Engine Python 3 runtime, refer to the [migration guide](/appengine/migration-center/standard/migrate-to-second-gen/python-differences) to learn about your migration options for legacy bundled services.\n\nIn addition to the [DB datastore exceptions](/appengine/docs/legacy/standard/python/datastore/exceptions), the NDB datastore provides the following exception classes:\n\nexception ComputedPropertyError()\n: Raised when attempting to set a value to or delete a computed property.\n\nexception InvalidPropertyError()\n: Raised when a property is not applicable to a given use. For example, a property must exist and be indexed to be used in a query's projection or group by clause.\n\nexception ReadonlyPropertyError()\n: Raised when attempting to set a property value that is read-only.\n\nexception UnprojectedPropertyError()\n: Raised when getting a property value that's not in the projection."]]
