MongoDB查询-限制名称与模式匹配的字段 [英] MongoDB Query - limit fields where name matches pattern

问题描述

我已经阅读了有关MongoDB中Projection的所有内容.我希望这很简单，但是由于Mongo查询具有压倒性的灵活性，我只是想念它.

I've read everything I can find about Projection in MongoDB. I'm hoping this is simple and I just missed it due to the overwhelming flexibility of Mongo queries.

在MySql数据库中，我们采用了一种商业惯例，即隐藏"字段以下划线作为前缀.我们的应用程序知道如何隐藏这些字段.

In our MySql database, we've adopted a business practice of having "hidden" fields be prefixed with an underscore. Our application knows how to hide these fields.

将一些数据移动到mongo，我需要检索文档，所有下划线前缀字段均省略.当然，这应该在查询中完成，而不要在检索后进行文档处理.

Moving some data to mongo, I need to retrieve the documents, with ALL underscore prefixed fields omitted. Of course this should be done in the query rather than document manipulation after retrieval.

$ regex，$ in，$ all之类的所有运算符似乎都适用于 values .我需要建立一个基于其名称而忽略未知数量字段的投影.像这样:

All the operators like $regex, $in, $all seem to apply to values. I need to build a projection that ignores an unknown number of fields based on their name. Something like:

db.coll.find({}, {"_*": 0})

当然不行，但是可以解释这个想法.

Of course that doesn't work, but explains the idea.

我应该注意:这是必要的，因为文档可以由我们的应用程序用户编辑，因此我不知道该架构是什么样的.我确实知道我们的内部"字段以_作为前缀，并且需要通过省略编辑器来保护这些字段.

I should note: this is necessary because the documents are editable by our application users, so I have no idea what the schema might look like. I do know our "internal" fields are prefixed with an _, and those need to be protected by omission from the editor.

希望这很简单...

推荐答案

您可以使用hidden_fields之类的单独字段.请参阅以下架构.

You can have a separate field as hidden_fields or something. See the following schema.

{_id: 'myid1', hidden_fields: {"_foo": "bar", "_foo2": "bar2"}, key1: value1 ...}

现在在上述模式的基础上就可以了，

Now on the basis of above schema just do,

db.collection.find({ ... }, {hidden_fields: 1})

这将显示隐藏的字段.此外，您还可以在子文档中的字段上建立索引，因此也不会损失性能.

This will display hidden fields. Also you can have indexes on fields within sub documents so no loss in terms of performance as well.

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