我是 MongoDB 世界的新手，现在我正在苦苦思索如何删除、更新文档的嵌套数组字段中的元素。这是我的示例文档:

{
    "_id" : ObjectId("55f354533dd61e5004ca5208"),
    "Name" : "Hand made products for real!",
    "Description" : "Products all made by hand",
    "Products" : [ 
        {
            "Identifier" : "170220151653",
            "Price" : 20.5,
            "Name" : "Leather bracelet",
            "Description" : "The bracelet was made by hand",
            "ImageUrl" : "https://encrypted-tbn1.gstatic.com/images?q=tbn:ANd9GcQii6JCvXtx0iJGWgpvSl-KrdZONKYzDwS0U8uDvUunjO6BO9Aj"
        }
    ]
} 

在我的方法中，我得到了文档的 id 和要删除的产品的 id(Identifier)。谁能告诉我如何从 Products 字段中删除具有标识符的元素:170220151653？

我试过了:

var query = Query.And(Query.EQ("_id", categoryId), Query.EQ("Products.Identifier", productId));
var update = Update.Pull("Products", new BsonDocument() { { "Identifier", productId } });
myDb.Applications().Update(query, update);

这里建议:MongoDB remove a subdocument document from a subdocument

但我在

myDb.Applications()

就是找不到。

已解决:

var pull = Update<Category>.Pull(x => x.Products, builder => builder.EQ(q => q.Identifier, productId));
collection.Update(Query.And(Query.EQ("_id", ObjectId.Parse(categoryId)), Query.EQ("Products.Identifier", productId)), pull);

最佳答案

您正在调用方法 Pull(string name, MongoDB.Bson.BsonValue value) 并根据文档

Removes all values from the named array element that are equal to some value (see $pull)

并且您提供 { "Identifier", productId } 作为值。我猜 mongo 没有找到那个 exact 值。

尝试将 Pull 的第二个重载与查询条件一起使用而不是精确值

Removes all values from the named array element that match some query (see $pull).

var update = Update.Pull("Products", Query.EQ("Identifier", productId));

更新

既然你提到了 Category 实体，所以我可以建议使用 lambda 而不是 Query.EQ:

var pull = Update<Category>.Pull(x => x.Products, builder =>
builder.Where(q => q.Identifier == productId));

https://stackoverflow.com/questions/28585206/