获取具有多个条件的 MongoDB 集合记录

Question

我想获取具有多个条件的 mongodb 集合，但出现错误：

panic: Failed to parse: filter: [ { visibility: { $eq: "4" } }, { 
discontinued: { $ne: "1" } }, { status: { $eq: "1" } } ]. 'filter' field 
must be of BSON type Object.

代码如下：

package main

import (
    "fmt"
    "gopkg.in/mgo.v2/bson"
)

func GenerateFeed(headers, attributes interface{}, conditions 
[]interface{}) {
    var operations = []bson.M{}

    for _, val := range conditions {
        var attr, operator, value interface{}
        cons := val.(map[interface{}]interface{})
        for range cons {
            attr     = cons["attribute"]
            operator = cons["operator"]
            value    = cons["value"]

            switch operator {
                case "==":
                    operator = "$eq"
                case "!=":
                    operator = "$ne"
                case "()":
                    operator = "$in"
            }
        }
        operations = append(operations, bson.M{attr.(string): 
        bson.M{operator.(string): value}})
    }

    var products []Prod

    session := Connect()
    collection := session.DB("rfgv2").C("catalog_product_entity_1")
    err := collection.Find(operations).All(&products)
    CheckError(err)

    fmt.Println(products)
}

type Prod struct {
    EntityId                string  `bson:"entity_id"`
    Name                    string  `bson:"name"`
    TypeId                  string  `bson:"type_id"`
    Sku                     string  `bson:"sku"`
    Manufacturer            int32   `bson:"manufacturer"`
    Status                  int32   `bson:"status"`
    Visibility              int32   `bson:"visibility"`
    EnableGoogleCheckout    int32   `bson:"enable_google_checkout"`
    Delivery                string  `bson:"delivery"`
    MetaTitle               string  `bson:"meta_title"`
    MetaDescription         string  `bson:"meta_description"`
    Image                   string  `bson:"image"`
    SmallImage              string  `bson:"small_image"`
    Thumbnail               string  `bson:"thumbnail"`
    Gallery                 string  `bson:"gallery"`
    UrlKey                  string  `bson:"url_key"`
    UrlPath                 string  `bson:"url_path"`
    Mpn                     string  `bson:"mpn"`
    ProductListingAds       string  `bson:"product_listing_ads"`
    Color                   string  `bson:"color"`
    Price                   float32 `bson:"price"`
    Cost                    float32 `bson:"cost"`
    TierPriceForBundle      float32 `bson:"tier_price_for_bundle"`
    RegularPrice            float32 `bson:"regular_price"`
    SpecialFromDate         string  `bson:"special_from_date"`
    Description             string  `bson:"description"`
    MetaKeyword             string  `bson:"meta_keyword"`
    Dimensions              string  `bson:"dimensions"`
    Features                string  `bson:"features"`
    DeliveryPopupMessage    string  `bson:"delivery_popup_message"`
    CreatedAt               string  `bson:"created_at"`
    UpdatedAt               string  `bson:"updated_at"`
}

我正在尝试使用 go 从 mongodb 获取基于多个聚合函数的记录。基本上如果我们删除方括号并尝试使用 mongo 命令它可以工作，但是如何在 go 中解决这个问题？

谢谢。

Answer 1

问题在于您将operations 声明为[]bson.M{}，因此您获得了一组地图。

如果您检查 bson.M{} 的 definition，它是一个 map[string]interface{} 您只需要向地图添加元素（在您的情况下是您想要的操作）。为此，语法为yourMap[yourKey] = yourValue。

尝试以下代码生成操作循环：

operations := bson.M{}
for _, val := range conditions {
    var attr, operator, value interface{}
    cons := val.(map[interface{}]interface{})
    for range cons {
        attr     = cons["attribute"]
        operator = cons["operator"]
        value    = cons["value"]

        switch operator {
            case "==":
                operator = "$eq"
            case "!=":
                operator = "$ne"
            case "()":
                operator = "$in"
        }
    }
        operations[attr.(string)] = bson.M{operator.(string): value}
}