conflict.js

conflict.js

db.changes({
  since: 'now',
  live: true,
  include_docs: true,
  conflicts: true
}).on('change', function (change) {
  let doc = change.doc;
  if(doc._conflicts) {
    let conflicts = doc._conflicts.concat();
    let promises = [doc._rev].concat(conflicts).map(function(rev){
      return db.get(doc._id, {rev: rev, revs_info: true});
    });

    Promise.all(promises).then(function(leafs){
      var ancestors = findCommonAncestors(leafs);

      if(ancestors.length) {
        return db.get(doc._id, {rev: ancestors[0]}).then(function(root){
          return diffAndMergeDocs(leafs, root);
        });
      } else {
        return diffAndMergeDocs(leafs);
      }
    }).then(function(merged){

      function putDoc(newDoc, conflicts){
        var bulk = conflicts.map(function(revid){
          return {
            _id: newDoc._id,
            _rev: revid,
            _deleted: true
          };
        });

        if(!deepEquals(newDoc.data, doc.data)) {
          // create new version only if old winning is different
          // it should avoid infinite loops between clients
          bulk = bulk.concat(newDoc);
        }

        db.bulkDocs(bulk).then(function(res){
          // success
        }).catch(function(res){
          if(res.status === 409) {
            // new conflicts
          } else{
            // handle error
          }
        });
      }

      putDoc(merged, conflicts);

    }).catch(function(res){
      console.log('change conflict resolution : get error', res);
    });
  }
});