How to use pouchdb-merge - 10 common examples

txn.objectStore(DOC_STORE).get(id).onsuccess = function (e) {
      metadata = decodeMetadata(e.target.result);
      // we can determine the result here if:
      // 1. there is no such document
      // 2. the document is deleted and we don't ask about specific rev
      // When we ask with opts.rev we expect the answer to be either
      // doc (possibly with _deleted=true) or missing error
      if (!metadata) {
        err = createError(MISSING_DOC, 'missing');
        return finish();
      }

      var rev;
      if (!opts.rev) {
        rev = metadata.winningRev;
        var deleted = isDeleted(metadata);
        if (deleted) {
          err = createError(MISSING_DOC, "deleted");
          return finish();
        }
      } else {
        rev = opts.latest ? getLatest(opts.rev, metadata) : opts.rev;
      }

      var objectStore = txn.objectStore(BY_SEQ_STORE);
      var key = metadata.id + '::' + rev;

      objectStore.index('_doc_id_rev').get(key).onsuccess = function (e) {
        doc = e.target.result;
        if (doc) {
          doc = decodeDoc(doc);
        }

rootIsMissing(doc)) {
        newDoc = createError(REV_CONFLICT);

      // Update the existing document
      } else if (oldDocs.hasOwnProperty(doc.id)) {
        newDoc = update(txn, doc, oldDocs[doc.id]);
        // The update can be rejected if it is an update to an existing
        // revision, if so skip it
        if (newDoc == false) {
          return;
        }

      // New document
      } else {
        // Ensure new documents are also stemmed
        var merged = merge([], doc.rev_tree[0], docsRevsLimit(doc));
        doc.rev_tree = merged.tree;
        doc.stemmedRevs = merged.stemmedRevs;
        newDoc = doc;
        newDoc.isNewDoc = true;
        newDoc.wasDeleted = doc.revs[doc.rev].deleted ? 1 : 0;
      }

      if (newDoc.error) {
        results[i] = newDoc;
      } else {
        oldDocs[newDoc.id] = newDoc;
        lastWriteIndex = i;
        write(txn, newDoc, i);
      }
    });
  }

// Ignore updates to existing revisions
    if ((doc.rev in oldDoc.revs) && !opts.new_edits) {
      return false;
    }

    var isRoot = /^1-/.test(doc.rev);

    // Reattach first writes after a deletion to last deleted tree
    if (oldDoc.deleted && !doc.deleted && opts.new_edits && isRoot) {
      var tmp = doc.revs[doc.rev].data;
      tmp._rev = oldDoc.rev;
      tmp._id = oldDoc.id;
      doc = convertDocFormat(parseDoc(tmp, opts.new_edits, dbOpts));
    }

    var merged = merge(oldDoc.rev_tree, doc.rev_tree[0], docsRevsLimit(doc));
    doc.stemmedRevs = merged.stemmedRevs;
    doc.rev_tree = merged.tree;

    // Merge the old and new rev data
    var revs = oldDoc.revs;
    revs[doc.rev] = doc.revs[doc.rev];
    doc.revs = revs;

    doc.attachments = oldDoc.attachments;

    var inConflict = opts.new_edits && (((oldDoc.deleted && doc.deleted) ||
       (!oldDoc.deleted && merged.conflicts !== 'new_leaf') ||
       (oldDoc.deleted && !doc.deleted && merged.conflicts === 'new_branch') ||
       (oldDoc.rev === doc.rev)));

    if (inConflict) {

stores.docStore.get(id, function (err, metadata) {

      if (err || !metadata) {
        return callback(createError(MISSING_DOC, 'missing'));
      }

      var rev;
      if (!opts.rev) {
        rev = getWinningRev(metadata);
        var deleted = getIsDeleted(metadata, rev);
        if (deleted) {
          return callback(createError(MISSING_DOC, "deleted"));
        }
      } else {
        rev = opts.latest ? getLatest(opts.rev, metadata) : opts.rev;
      }

      var seq = metadata.rev_map[rev];

      stores.bySeqStore.get(formatSeq(seq), function (err, doc) {
        if (!doc) {
          return callback(createError(MISSING_DOC));
        }
        /* istanbul ignore if */
        if ('_id' in doc && doc._id !== metadata.id) {
          // this failing implies something very wrong
          return callback(new Error('wrong doc returned'));
        }
        doc._id = metadata.id;
        if ('_rev' in doc) {
          /* istanbul ignore if */

// doc (possibly with _deleted=true) or missing error
      if (!metadata) {
        err = createError(MISSING_DOC, 'missing');
        return finish();
      }

      var rev;
      if (!opts.rev) {
        rev = metadata.winningRev;
        var deleted = isDeleted(metadata);
        if (deleted) {
          err = createError(MISSING_DOC, "deleted");
          return finish();
        }
      } else {
        rev = opts.latest ? getLatest(opts.rev, metadata) : opts.rev;
      }

      var objectStore = txn.objectStore(BY_SEQ_STORE);
      var key = metadata.id + '::' + rev;

      objectStore.index('_doc_id_rev').get(key).onsuccess = function (e) {
        doc = e.target.result;
        if (doc) {
          doc = decodeDoc(doc);
        }
        if (!doc) {
          err = createError(MISSING_DOC, 'missing');
          return finish();
        }
        finish();
      };

txn.txn.objectStore(DOC_STORE).get(id).onsuccess = function (e) {
    var doc = e.target.result;
    var rev;
    if (!opts.rev) {
      rev = (doc && doc.rev);
    } else {
      rev = opts.latest ? getLatest(opts.rev, doc) : opts.rev;
    }

    if (!doc || (doc.deleted && !opts.rev) || !(rev in doc.revs)) {
      callback(createError(MISSING_DOC, 'missing'));
      return;
    }

    var result = doc.revs[rev].data;
    result._id = doc.id;
    result._rev = rev;

    // WARNING: expecting possible old format
    // TODO: why are we passing the transaction in the context?
    //       It's not clear we ever thread these txns usefully
    callback(null, {
      doc: result,

var conflicts = collectConflicts(metadata);
      if (conflicts.length) {
        doc._conflicts = conflicts;
      }
    }

    if (isDeleted(metadata, doc._rev)) {
      doc._deleted = true;
    }

    if (opts.revs || opts.revs_info) {
      var splittedRev = doc._rev.split('-');
      var revNo       = parseInt(splittedRev[0], 10);
      var revHash     = splittedRev[1];

      var paths = rootToLeaf(metadata.rev_tree);
      var path = null;

      for (var i = 0; i < paths.length; i++) {
        var currentPath = paths[i];
        var hashIndex = currentPath.ids.map(function (x) { return x.id; })
          .indexOf(revHash);
        var hashFoundAtRevPos = hashIndex === (revNo - 1);

        if (hashFoundAtRevPos || (!path && hashIndex !== -1)) {
          path = currentPath;
        }
      }

      /* istanbul ignore if */
      if (!path) {
        err = new Error('invalid rev tree');

function insertDoc(docInfo, resultsIdx, callback) {
    // Cant insert new deleted documents
    var winningRev = calculateWinningRev(docInfo.metadata);
    var deleted = isDeleted(docInfo.metadata, winningRev);
    if ('was_delete' in opts && deleted) {
      results[resultsIdx] = createError(MISSING_DOC, 'deleted');
      return callback();
    }

    // 4712 - detect whether a new document was inserted with a _rev
    var inConflict = newEdits && rootIsMissing(docInfo);

    if (inConflict) {
      var err = createError(REV_CONFLICT);
      results[resultsIdx] = err;
      return callback();
    }

    var delta = deleted ? 0 : 1;

cursor.onsuccess = function (e) {
      var cursor = e.target.result;
      if (!cursor) {
        return; // done
      }
      var metadata = decodeMetadataCompat(cursor.value);

      metadata.winningRev = metadata.winningRev ||
        calculateWinningRev(metadata);

      function fetchMetadataSeq() {
        // metadata.seq was added post-3.2.0, so if it's missing,
        // we need to fetch it manually
        var start = metadata.id + '::';
        var end = metadata.id + '::\uffff';
        var req = bySeqStore.index('_doc_id_rev').openCursor(
          IDBKeyRange.bound(start, end));

        var metadataSeq = 0;
        req.onsuccess = function (e) {
          var cursor = e.target.result;
          if (!cursor) {
            metadata.seq = metadataSeq;
            return onGetMetadataSeq();
          }

function allDocsInner(data) {
          var doc = {
            id: metadata.id,
            key: metadata.id,
            value: {
              rev: winningRev
            }
          };
          if (opts.include_docs) {
            doc.doc = data;
            doc.doc._rev = doc.value.rev;
            if (opts.conflicts) {
              doc.doc._conflicts = collectConflicts(metadata);
            }
            for (var att in doc.doc._attachments) {
              if (doc.doc._attachments.hasOwnProperty(att)) {
                doc.doc._attachments[att].stub = true;
              }
            }
          }
          if (opts.inclusive_end === false && metadata.id === opts.endkey) {
            return next();
          } else if (deleted) {
            if (opts.deleted === 'ok') {
              doc.value.deleted = true;
              doc.doc = null;
            } else {
              /* istanbul ignore next */
              return next();