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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Passing an optional parameter to startAt() when querying FirebaseListObservable","articleBody":"Hey,\n\nI'm using a FirebaseListObservable to retrieve some messages from firebase and I was wondering how to use the firebase query startAt() method inside the query object. It's not a simple startAt(value) call, since I need to pass in the optional \"key\" parameter. However, it seems that there's no easy or straightforward way to accomplish that within the query object.\n\nI tried the following: \n\n``` javascript\n    this.af.database.list('/messages', { \n    query: { \n        orderByChild: 'date', \n        startAt: {value: 'Some date', key: 'some key'}, //key is the optional parameter \n        limitToFirst: 10\n        }\n        })\n```\n\nbut the firebase library (not angularfire2) complains: \n\nORIGINAL EXCEPTION: Error: Query: First argument passed to startAt(), endAt(), or equalTo() cannot be an object.\n\nThe startAt method can receive an optional parameter \"key\", as described in the firebase docs:\nhttps://firebase.google.com/docs/reference/js/firebase.database.Query#startAt\n\nI even tried $value and $key as the object properties, but firebase threw another Error.\n\nIs this impossible to do with angularfire or is there a different syntax to do it?\n\nThis is how the query looks like with vanilla firebase:\nfirebase.database().ref('/messages').orderByChild('date').startAt(startAtValue, someKey).limitToFirst(10);\n","author":{"url":"https://github.com/lf-alves","@type":"Person","name":"lf-alves"},"datePublished":"2016-07-16T23:03:43.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":11},"url":"https://github.com/362/angularfire/issues/362"}