使用MongoDB C#驱动程序从所有文档中删除数组元素 [英] Remove array element from ALL documents using MongoDB C# driver

问题描述

给出以下内容:

{
    "_id" : 1,
    "name" : "Nature",
    "area": [
        {
            "place": "Some place",
            "discoveredBy": ""
        },
        {
            "place": "Some place 2",
            "discoveredBy": ""
        }
    ],
    "_id" : 2,
    "name" : "Tropics",
    "area": [
        {
            "place": "Some place",
            "discoveredBy": ""
        },
        {
            "place": "Some place 2",
            "discoveredBy": ""
        }
    ]
}

在代码中，我删除了createdBy属性.现在如何使用C#驱动程序更新(取消设置)我的ENTIRE数据库，从而也删除了createdBy?生成的数据库应如下所示:

In code, I deleted the discoveredBy property. How do I now update (unset) my ENTIRE db using the C# driver so that discoveredBy is also deleted? The resulting db should look like:

{
    "_id" : 1,
    "name" : "Nature",
    "area": [
        {
            "place": "Some place"
        },
        {
            "place": "Some place 2"
        }
    ],
    "_id" : 2,
    "name" : "Tropics",
    "area": [
        {
            "place": "Some place"
        },
        {
            "place": "Some place 2"
        }
    ]
}

当前，在我更改代码后尝试执行查找"时，此操作失败，因为DiscoverBy属性不再存在于代码中，并且序列化过程无法找到存储仍存在于db中的已删除属性的位置.因此，需要从数据库中完全删除该字段.

Currently when trying to perform a Find after my code change, it's failing because the discoveredBy property is no longer in code and the serialization processes can't find a place to store the removed property which still exists in the db. Hence the need to delete that field from the db in its entirety.

已更新解决方案:

感谢所有输入专家，但这并不是重复的，因为当我尝试使用新驱动程序在C#中运行时，我尝试过的一切似乎都已被弃用.无论哪种方式，这都是我最终确定的解决方案.这里的键是使用"$ []" ，根据MongoDB，它是3.6版以来的新功能.请参见 https://docs.mongodb. com/manual/reference/operator/update/positional-all/#up. S [] 了解更多信息.

Thanks for all the input guys but this isn't a duplicate as everything I tried seemed to be deprecated when I tried running in C# with the new driver. Either way, here's the fix I eventually settled on. The key here is using "$[]" which according to MongoDB is new as of version 3.6. See https://docs.mongodb.com/manual/reference/operator/update/positional-all/#up.S[] for more information.

代码如下:

{
   var filter = Builders<Scene>.Filter.Where(i => i.ID != null);
   var update = Builders<Scene>.Update.Unset("area.$[].discoveredBy");
   var result = collection.UpdateMany(filter, update, new UpdateOptions { IsUpsert = true});
}

推荐答案

在您的情况下，请执行以下操作:

In your case do something like this:

db.collectionname.find({}).forEach(function(item) {
var ar = item.area;
for(var i = 0; i < ar.length; ++i) { 
    var x = ar[i];
    delete (x["discoveredBy"]);

}
db.collectionname.save(item);});

这篇关于使用MongoDB C#驱动程序从所有文档中删除数组元素的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！