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Use async/await and for..of in Cloud Firestore
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| // In a Firestore standard example, we quickly create a 'xmas tree' of nested stuff | |
| // We use Promises directly: get().then(callback) and use snapshot.forEach() to iterate | |
| let campaignsRef = db.collection('campaigns'); | |
| let activeCampaigns = campaignsRef.where('active', '==', true).select().get() | |
| .then(snapshot => { | |
| snapshot.forEach(campaign => { | |
| console.log(campaign.id); | |
| let allTasks = campaignsRef.doc(campaign.id).collection('tasks').get().then( | |
| snapshot => { | |
| snapshot.forEach(task => { | |
| console.log(task.id, task.data()) | |
| }); | |
| } | |
| ) | |
| }); | |
| }) | |
| .catch(err => { | |
| console.log('Error getting documents', err); | |
| }); |
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| // In the async/await example, we need to wrap our code inside a function | |
| // and mark it as 'async'. This allows us to 'await' on a Promise. | |
| async function process_tasks() { | |
| let campaignsRef = db.collection('campaigns') | |
| let activeRef = await campaignsRef.where('active', '==', true).select().get(); | |
| for (campaign of activeRef.docs) { | |
| console.log(campaign.id); | |
| let tasksRef = await campaign.collection('tasks').get(); | |
| for(task of tasksRef.docs) { | |
| console.log(task.id, task.data()) | |
| } | |
| } | |
| } | |
| // Call our async function in a try block to catch connection errors. | |
| try { | |
| process_tasks(); | |
| } | |
| catch(err) { | |
| console.log('Error getting documents', err) | |
| } |
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