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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"idField on valueChanges doesn't work as expected.","articleBody":"### Version info\r\n\r\n**Angular: 11**\r\n\r\n**Firebase: 8**\r\n\r\n**AngularFire: 6**\r\n\r\n**Other: MacOS Big Sur**\r\n\r\n### Issue\r\n\r\nWhen you call valueChanges on a document you know doesn't exist, it emits undefined. However if you specify idField, for example, as id, then it will return an object with the field id. I expected that it would still return undefined. It returning causes problems, as the object then isn't in the shape you expect (if you specify a type of the result) but also you get a result when a document doesn't actually exist.\r\n\r\nI think the issue is simply in the valueChanges function:\r\n\r\n```\r\nvalueChanges\u003cK extends string\u003e(options: { idField?: K } = {}): Observable\u003cT | undefined\u003e {\r\n  return this.snapshotChanges().pipe(\r\n    map(({ payload }) =\u003e\r\n      options.idField ? {\r\n        ...payload.data(),\r\n        ...{ [options.idField]: payload.id }\r\n      } as T \u0026 { [T in K]: string } : payload.data()\r\n    )\r\n  );\r\n}\r\n```\r\n\r\nAs you can see, if payload.data() is undefined, this function will create an object with id field. I think a simple fix would be:\r\n\r\n```\r\nvalueChanges\u003cK extends string\u003e(options: { idField?: K } = {}): Observable\u003cT | undefined\u003e {\r\n  return this.snapshotChanges().pipe(\r\n    map(({ payload }) =\u003e\r\n      options.idField \u0026\u0026 payload.data() ? {\r\n        ...payload.data(),\r\n        ...{ [options.idField]: payload.id }\r\n      } as T \u0026 { [T in K]: string } : payload.data()\r\n    )\r\n  );\r\n}\r\n```\r\n\r\nI don't actually know much about the underlying firebase apis, but I'm assuming that payload.data() is undefined if there is no document.","author":{"url":"https://github.com/ammaarpatel99","@type":"Person","name":"ammaarpatel99"},"datePublished":"2021-02-07T12:06:01.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":5},"url":"https://github.com/2753/angularfire/issues/2753"}