Generate MongoDB index creation commands from the console

generateIndexCreationCommands.js

// Reads indexes from a running db and prints out commands to create those
// indexes in another db, for use in those cases where you restored a dump with
// --noIndexRestore.
// Just copy & paste into the MongoDB shell.
db.getCollectionNames().forEach(function(collection) {
  var cleanIndexesBesidesId = []; 
  var indexes = db.getCollection(collection).getIndexes();

  indexes.forEach(function(i) {
    if (i.name === '_id_') {
       return;
    }
    if (i.sparse) {
      i.sparse = true; // might be int 1, let's conform
    }
    // let MongoDB set these
    delete(i.v);
    delete(i.ns);
    // prune invalid keys because they crash MongoDB 3.4
    delete(i.safe); // https://github.com/meteor/meteor/pull/4340
    delete(i.w); // ??
    cleanIndexesBesidesId.push(i);
  });

  if (cleanIndexesBesidesId.length) {
    cleanIndexesBesidesId.forEach(function(i) {
      var extraArgs = {};
      extraArgs.name = i.name;
      extraArgs.background = true;
      if (i.unique) {
        extraArgs.unique = true;
      }
      if (i.sparse) {
        extraArgs.sparse = true;
      }
      if (i.expireAfterSeconds) {
        extraArgs.expireAfterSeconds = i.expireAfterSeconds;
      }
      print("db['" + collection + "'].createIndex(" + JSON.stringify(i.key) + ',' + JSON.stringify(extraArgs) + ');');
    });
  }
});