pouchdb-upsert/index.js

PouchDB upsert and putIfNotExists functions

'use strict';

var PouchPromise = require('pouchdb-promise');

// this is essentially the "update sugar" function from daleharvey/pouchdb#1388
// the diffFun tells us what delta to apply to the doc.  it either returns
// the doc, or false if it doesn't need to do an update after all
function upsertInner(db, docId, diffFun) {
  if (typeof docId !== 'string') {
    return PouchPromise.reject(new Error('doc id is required'));
  }

  return db.get(docId).catch(function (err) {
    /* istanbul ignore next */
    if (err.status !== 404) {
      throw err;
    }
    return {};
  }).then(function (doc) {
    // the user might change the _rev, so save it for posterity
    var docRev = doc._rev;
    var newDoc = diffFun(doc);

    if (!newDoc) {
      // if the diffFun returns falsy, we short-circuit as
      // an optimization
      return { updated: false, rev: docRev, id: docId };
    }

    // users aren't allowed to modify these values,
    // so reset them here
    newDoc._id = docId;
    newDoc._rev = docRev;
    return tryAndPut(db, newDoc, diffFun);
  });
}

function tryAndPut(db, doc, diffFun) {
  return db.put(doc).then(function (res) {
    return {
      updated: true,
      rev: res.rev,
      id: doc._id
    };
  }, function (err) {
    /* istanbul ignore next */
    if (err.status !== 409) {
      throw err;
    }
    return upsertInner(db, doc._id, diffFun);
  });
}

exports.upsert = function upsert(docId, diffFun, cb) {
  var db = this;
  var promise = upsertInner(db, docId, diffFun);
  if (typeof cb !== 'function') {
    return promise;
  }
  promise.then(function (resp) {
    cb(null, resp);
  }, cb);
};

exports.putIfNotExists = function putIfNotExists(docId, doc, cb) {
  var db = this;

  if (typeof docId !== 'string') {
    cb = doc;
    doc = docId;
    docId = doc._id;
  }

  var diffFun = function (existingDoc) {
    if (existingDoc._rev) {
      return false; // do nothing
    }
    return doc;
  };

  var promise = upsertInner(db, docId, diffFun);
  if (typeof cb !== 'function') {
    return promise;
  }
  promise.then(function (resp) {
    cb(null, resp);
  }, cb);
};


/* istanbul ignore next */
if (typeof window !== 'undefined' && window.PouchDB) {
  window.PouchDB.plugin(exports);
}