Function migrateMetadata

lib/index-browser.js:6049–6115

(txn)

  // - metadata.seq
  // - stringify the metadata when storing it
  function migrateMetadata(txn) {

    function decodeMetadataCompat(storedObject) {
      if (!storedObject.data) {
        // old format, when we didn't store it stringified
        storedObject.deleted = storedObject.deletedOrLocal === '1';
        return storedObject;
      }
      return decodeMetadata(storedObject);
    }

    // ensure that every metadata has a winningRev and seq,
    // which was previously created on-the-fly but better to migrate
    var bySeqStore = txn.objectStore(BY_SEQ_STORE);
    var docStore = txn.objectStore(DOC_STORE);
    var cursor = docStore.openCursor();
    cursor.onsuccess = function (e) {
      var cursor = e.target.result;
      if (!cursor) {
        return; // done
      }
      var metadata = decodeMetadataCompat(cursor.value);

      metadata.winningRev = metadata.winningRev ||
        winningRev(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();
          }
          var seq = cursor.primaryKey;
          if (seq > metadataSeq) {
            metadataSeq = seq;
          }
          cursor.continue();
        };
      }

      function onGetMetadataSeq() {
        var metadataToStore = encodeMetadata(metadata,
          metadata.winningRev, metadata.deleted);

        var req = docStore.put(metadataToStore);
        req.onsuccess = function () {
          cursor.continue();
        };
      }