使用req.body通过Mongoose更新和/或添加数组元素属性？

Question

我有以下文件：

{
    "_id" : ObjectId("503b83dfad79cc8d26000004"),
    "pdfs" : [
        {
            "title" : "Test document",
            "pdf_id" : ObjectId("504f6793ce351a595d000004"),
            "created_at" : ISODate("2012-09-11T16:32:19.276Z")
        },
        {
            "title" : "Some other doc",
            "pdf_id" : ObjectId("502bf124b4642341230003f0"),
            "created_at" : ISODate("2012-09-11T11:34:19.276Z")
        }
    ]
}

现在通过req.body传入表单，我有两个字段：title和description。

我想更新title并为指定的pdf_id插入description，我该怎么做？

所以最后，我的文档现在看起来像：

{
    "_id" : ObjectId("503b83dfad79cc8d26000004"),
    "pdfs" : [
        {
            "title" : "This is an UPDATED title",
            "description" : "It has an ALL NEW description",
            "pdf_id" : ObjectId("504f6793ce351a595d000004"),
            "created_at" : ISODate("2012-09-11T16:32:19.276Z")
        },
        {
            "title" : "Some other doc",
            "pdf_id" : ObjectId("502bf124b4642341230003f0"),
            "created_at" : ISODate("2012-09-11T11:34:19.276Z")
        }
    ]
}

为了清楚起见，我真的只是在寻找Mongoose update语法。

Answer 1

您可以使用$ positional operator来引用pdfs中匹配的$set数组元素：

Model.update(
    { 'pdfs.pdf_id': pdf_id }, 
    { $set: { 
        'pdfs.$.title': title, 
        'pdfs.$.description': description 
    }}, function (err, numAffected) { ... }
);