mongodb-go-driver/bson结构转换为bson.Document编码 [英] mongodb-go-driver/bson struct to bson.Document encoding

问题描述

我正在使用 https://github.com/mongodb/mongo-go-driver 和 当前正在尝试对该结构进行部分更新

I'm working with https://github.com/mongodb/mongo-go-driver and currently trying to implement a partial update of such struct

type NoteUpdate struct {
    ID        string `json:"id,omitempty" bson:"_id,omitempty"`
    Title     string `json:"title" bson:"title,omitempty"`
    Content   string `json:"content" bson:"content,omitempty"`
    ChangedAt int64  `json:"changed_at" bson:"changed_at"`
}

例如，如果我有

noteUpdate := NoteUpdate{ Title: "New Title" }

然后，我希望存储文档中唯一的标题"字段将被更改.

Then I expect that the only "title" field in the stored document will be changed.

我需要写一些类似的东西

I need to write something like

collection.FindOneAndUpdate(context.Background(),
    bson.NewDocument(bson.EC.String("_id", noteUpdate.ID)),
    // I need to encode non-empty fields here
    bson.NewDocument(bson.EC.SubDocument("$set", bson.NewDocument(...)))
)

问题是我不想用bson.EC.String(...)或bson.EC.Int64(...)手动编码每个非空字段.我尝试使用bson.EC.InterfaceErr(...)但出现错误

The problem is that I don't want to manually encode each non-empty field with bson.EC.String(...) or bson.EC.Int64(...). I tried to use bson.EC.InterfaceErr(...) but got an error

无法为* models.NoteUpdate类型创建元素，请尝试使用bsoncodec.ConstructElementErr

Cannot create element for type *models.NoteUpdate, try using bsoncodec.ConstructElementErr

不幸的是，bsoncodec中没有这样的功能.我发现的唯一方法是创建包装器

Unfortunately, there is no such function in bsoncodec. The only way I found is to create wrapper

type SetWrapper struct {
    Set interface{} `bson:"$set,omitempty"`
}

并像使用它

partialUpdate := &NoteUpdate{
    ID: "some-note-id", 
    Title: "Some new title",
 }
updateParam := SetWrapper{Set: partialUpdate}
collection.FindOneAndUpdate(
    context.Background(),
    bson.NewDocument(bson.EC.String("_id", noteUpdate.ID)),
    updateParam,
)

它可以工作，但是可以使用bson/bsoncodec文档构建器实现相同的功能吗?

It works, but is it possible to achieve the same with bson/bsoncodec document builders ?

UPD.我的问题的全部内容: 我编写了REST端点，用于部分更新"Note"文档(存储在MongoDB中).我现在拥有的代码:

UPD. The full context of my question: I wrote the REST endpoint for partially updating "Note" documents(stored in MongoDB). Code that I have now:

var noteUpdate models.NoteUpdate
ctx.BindJSON(&noteUpdate)    
//omit validation and errors handling
updateParams := services.SetWrapper{Set: noteUpdate}
res := collection.FindOneAndUpdate(
context.Background(),
bson.NewDocument(bson.EC.String("_id", noteUpdate.ID)),
    updateParams,
    findopt.OptReturnDocument(option.After),
)

我想要的代码

var noteUpdate models.NoteUpdate
ctx.BindJSON(&noteUpdate)    
//omit validation and errors handling
res := collection.FindOneAndUpdate(
    context.Background(),
    bson.NewDocument(bson.EC.String("_id", noteUpdate.ID)),
    bson.NewDocument(
        //bsoncodec.ConstructElement doesn't exists
        bsoncodec.ConstructElement("$set", &noteUpdate)),
        ),
    findopt.OptReturnDocument(option.After),
)

我不想想要的代码

var noteUpdate models.NoteUpdate
ctx.BindJSON(&noteUpdate)
//omit validation and errors handling
bsonNote := bson.NewDocument()
if noteUpdate.Title != "" {
    bsonNote.Append(bson.EC.String("title", noteUpdate.Title))
}
if noteUpdate.Content != "" {
    bsonNote.Append(bson.EC.String("content", noteUpdate.Content))
}
//..setting the rest of the fields...
res := collection.FindOneAndUpdate(
    context.Background(),
    bson.NewDocument(bson.EC.String("_id", noteUpdate.ID)),
    bson.NewDocument(bson.EC.SubDocument("$set", bsonNote)),
    findopt.OptReturnDocument(option.After),
)

因此，确切的问题是-是否有任何方法可以基于bson标签(没有像我的SetWrapper这样的预定义包装器)动态地构建* bson.Document?

So, the precise question is - is there any way to build *bson.Document dynamically based on bson tags(without predefined wrappers like my SetWrapper)?

推荐答案

很遗憾，当前不支持此功能.

Unfortunately this is currently not supported.

您可以创建一个辅助函数，以将结构值转换"为

You may create a helper function which "converts" a struct value to a bson.Document like this:

func toDoc(v interface{}) (doc *bson.Document, err error) {
    data, err := bson.Marshal(v)
    if err != nil {
        return
    }

    err = bson.Unmarshal(data, &doc)
    return
}

然后可以像这样使用它:

Then it can be used like this:

partialUpdate := &NoteUpdate{
    Title: "Some new title",
}

doc, err := toDoc(partialUpdate)
// check error

res := c.FindOneAndUpdate(
    context.Background(),
    bson.NewDocument(bson.EC.String("_id", "some-note-id")),
    bson.NewDocument(bson.EC.SubDocument("$set", doc)),
)

希望 ElementConstructor.Interface() 将将来会有所改进，并允许直接将结构值或指针传递给结构值.

Hopefully ElementConstructor.Interface() will improve in the future and allow passing struct values or pointers to struct values directly.

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