使用mongo C＃驱动程序，如何序列化自定义对象数组以便存储它？

Question

I have a product document that contains an array of documents. For example

{
 id: 1,
 name: "J-E-L-L-O",
 store:[{id: 1,
    name: "Store X"},
    {id: 2,
    name: "Store Y"}]
}

I would like to change the name of "Store Y" to Store Z", for instance. At the time, I don't know the index of the object. So, I pull the entire array, find the object to update, change the name, and then attempt to set the value of "store" with the updated array.

productCollection.Update(query, Update.Set("store", storeList.ToBsonDocument()));

However, I am getting an error: "An Array value cannot be written to the root level of a BSON document."

I think I just need to know how to serialize the array of custom objects to an array of BsonDocuments.

Thanks in advance for your help.

Answer 1

Unfortunately I had the same problem and ended up making an extension method to help me get around it.

    public static BsonArray ToBsonDocumentArray(this IEnumerable list)
    {
        var array = new BsonArray();
        foreach (var item in list)
        {
            array.Add(item.ToBson());
        }
        return array;
    }

so you should be able to do:

productCollection.Update(query, Update.Set("store", storeList.ToBsonDocumentArray()));

Answer 2

The exception says that you cannot convert an array/list into a BsonDocument. I think that you are looking to convert storeList to a [BsonArray][1] .

If storeList is already an array of BsonDocument or some IEnumerable<T> where to can be converted to a BsonDocument , the you should not need to cast the storeList variable at all.

Answer 3

you should use

BsonDocument.Parse(storeList);

instead of

storeList.ToBsonDocument()

Answer 4

Little edit for the accepted answer function:

public static BsonArray ToBsonDocumentArray(this IEnumerable list)
    {
        var array = new BsonArray();
        foreach (var item in list)
        {
            array.Add(item);
        }
        return array;
    }

we don't need to convert item.ToBson(). There is already an implicit conversion from string to bson.Thats the reason i was getting an error message " A String value cannot be written to the root level of a BSON document. "