Meteor 1.0 - MinimongoError: 无法使用字符串字段名 [-1] 附加到数组

Question

Meteor 1.0 是为 MongoDB v2.4 构建的，它没有 Mongo 2.6 中引入的 $position API。因此，我无法将数组项添加到 MongoDB 数组的开头：

{
  $push: {
    <field>: {
       $each: [ <value1>, <value2>, ... ],
       $position: 0
    }
  }
}

我尝试通过解决方法将项目添加到 MongoDB 数组的前面...

collectionName.update(
  {_id: 'Xjfb2bbsyj2maFu'},
  {$set:
    {'field.-1': data}
  }
);

...但这仅适用于服务器端代码，MiniMongo 无法解释：

I20141109-23:32:42.382(-5)? Error in oplog callback MinimongoError: can't append to array using string field name [-1]
I20141109-23:32:42.382(-5)?     at MinimongoError (packages/minimongo/minimongo.js:53)
I20141109-23:32:42.383(-5)?     at findModTarget (packages/minimongo/modify.js:133)
I20141109-23:32:42.383(-5)?     at packages/minimongo/modify.js:56
I20141109-23:32:42.383(-5)?     at Function._.each._.forEach     (packages/underscore/underscore.js:113)
I20141109-23:32:42.383(-5)?     at packages/minimongo/modify.js:43
I20141109-23:32:42.383(-5)?     at Function._.each._.forEach (packages/underscore/underscore.js:113)
I20141109-23:32:42.383(-5)?     at Function.LocalCollection._modify (packages/minimongo/modify.js:36)
I20141109-23:32:42.383(-5)?     at packages/mongo/oplog_observe_driver.js:597
I20141109-23:32:42.384(-5)?     at Object.Meteor._noYieldsAllowed (packages/meteor/fiber_helpers.js:11)
I20141109-23:32:42.384(-5)?     at _.extend._handleOplogEntrySteadyOrFetching (packages/mongo/oplog_observe_driver.js:545)

有什么解决方法可以将项目添加到与 Meteor 1.0 / MiniMongo 兼容的 MongoDB 数组的开头？

Answer 1

你需要原子性吗？如果没有，只需修改然后$set整个数组。

var doc = collectionName.findOne();
doc.arr.unshift('newElement');
collectionName.update(doc._id, {$set: {'arr': doc.arr}});

否则，听起来您现在需要在服务器端代码中执行此操作。