Modified from pouchdb-upsert.

A tiny plugin for PouchDB that provides convenience methods:

• upsert() - update a document, or insert a new one if it doesn't exist ("upsert"). Will keep retrying (default is 6 times) if it gets 409 conflicts.
• upsertEx() -
• putIfNotExists() - create a new document if it doesn't exist. Does nothing if it already exists.
• postEx() - create a new document if it doesn't exist. throw 409 error if it already exists.

So basically, if you're tired of manually dealing with 409s or 404s in your PouchDB code, then this is the plugin for you.

npm install pouchdb-upsertex

Then attach it to the PouchDB object:

var PouchDB = require('pouchdb');
PouchDB.plugin(require('pouchdb-upsertex'));

• async db.upsert(doc [, options])
• async db.upsertEx(docId, diffFunc [, options])
• async db.putIfNotExists([docId, ] doc [, options])
• async db.postEx(doc [, options])

async perform an insert operation. It will throw error if doc already exists.

• options: optional options which pass to db.put .
  • retry: the keep retry number, defaults to 6.

async perform an upsert (update or insert) operation.

• doc: the upserted document.
• options: optional options which pass to db.put .
  • retry: the keep retry number, defaults to 6.

async perform an upsert (update or insert) operation.

• docId - the _id of the document.
• diffFunc - function that takes the existing doc as input and returns an updated doc.
  • If this diffFunc returns falsey, then the update won't be performed (as an optimization).
  • If the document does not already exist, then {} will be the input to diffFunc.
• options: optional options which pass to db.put .
  • retry: the keep retry number, defaults to 6.

A doc with a basic counter:

db.upsertEx('myDocId', function (doc) {
  if (!doc.count) {
    doc.count = 0;
  }
  doc.count++;
  return doc;
}).then(function (res) {
  // success, res is {rev: '1-xxx', updated: true, id: 'myDocId'}
}).catch(function (err) {
  // error
});

Resulting doc (after 1 upsert):

{
  _id: 'myDocId',
  _rev: '1-cefef1ec19869d9441a47021f3fd4710',
  count: 1
}

Resulting doc (after 3 upserts):

{
  _id: 'myDocId',
  _rev: '3-536ef59f3ed17a181dc683a255caf1d9',
  count: 3
}

A diffFunc that only updates the doc if it's missing a certain field:

db.upsertEx('myDocId', function (doc) {
  if (!doc.touched) {
    doc.touched = true;
    return doc;
  }
  return false; // don't update the doc; it's already been "touched"
}).then(function (res) {
  // success, res is {rev: '1-xxx', updated: true, id: 'myDocId'}
}).catch(function (err) {
  // error
});

Resulting doc:

{
  _id: 'myDocId',
  _rev: '1-cefef1ec19869d9441a47021f3fd4710',
  touched: true
}

The next time you try to upsert, the res will be {rev: '1-xxx', updated: false, id: 'myDocId'}. The updated: false indicates that the upsert function did not actually update the document, and the rev returned will be the previous winning revision.

You can also return a new object. The _id and _rev are added automatically:

db.upsertEx('myDocId', function (doc) {
  return {thisIs: 'awesome!'};
}).then(function (res) {
  // success, res is {rev: '1-xxx', updated: true, id: 'myDocId'}
}).catch(function (err) {
  // error
});

Resulting doc:

{
  _id: 'myDocId',
  _rev: '1-cefef1ec19869d9441a47021f3fd4710',
  thisIs: 'awesome!'
}

async put a new document with the given docId, if it doesn't already exist.

• docId - the _id of the document. Optional if you already include it in the doc
• doc - the document to insert. Should contain an _id if docId is not specified

If the document already exists, then the Promise will just resolve immediately.

Put a doc if it doesn't exist

db.putIfNotExists('myDocId', {yo: 'dude'}).then(function (res) {
  // success, res is {rev: '1-xxx', updated: true, id: 'myDocId'}
}).catch(function (err) {
  // error
});

Resulting doc:

{
  _id: 'myDocId',
  _rev: '1-cefef1ec19869d9441a47021f3fd4710',
  yo: 'dude'
}

If you call putIfNotExists multiple times, then the document will not be updated the 2nd, 3rd, or 4th time (etc.).

If it's not updated, then the res will be {rev: '1-xxx', updated: false, id: 'myDocId'}, where rev is the first revision and updated: false indicates that it wasn't updated.

You can also just include the _id inside the document itself:

db.putIfNotExists({_id: 'myDocId', yo: 'dude'}).then(function (res) {
  // success, res is {rev: '1-xxx', updated: true, id: 'myDocId'}
}).catch(function (err) {
  // error
});

Resulting doc (same as example 1):

{
  _id: 'myDocId',
  _rev: '1-cefef1ec19869d9441a47021f3fd4710',
  yo: 'dude'
}