donglu9978 2014-02-15 17:03
浏览 23
已采纳

如何建立mgo查询?

I'm doing a tiny project(practice) with revel and mgo, but I got something wrong with search function when I build the queries. The code seems like this:

conditions := make(bson.M, 0)
conditions["status"] = bson.M{"$ne": "delete"}

if item, ok := paramsPost["title"]; ok {
    if item[0] != "" {
        conditions["title"] = bson.RegEx{Pattern: item[0]}
    }
}
if item, ok := paramsPost["from_date"]; ok {
    if item[0] != "" {
        conditions["publishdate"] = bson.M{}
        fromDate, _ := time.Parse("2006-01-02", item[0])
        conditions["publishdate"]["$gte"] = fromDate.Unix()
    }
}

if item, ok := paramsPost["to_date"]; ok {
    if _, ok := conditions["publishdate"]; !ok {
        conditions["publishdate"] = bson.M{}
    }
    if item[0] != "" {
        toDate, _ := time.Parse("2006-01-02", item[0])
        conditions["publishdate"]["$lte"] = toDate.Unix()
    }
}

And I got some error info:

invalid operation: conditions["publishdate"]["$gte"] (index of type interface {})

I know I make something wrong, but I don't know why, and how to resolve. Anybody can help me? Thanks

  • 写回答

1条回答 默认 最新

  • doujing3896 2014-02-15 22:45
    关注

    bson.M is a map[string]interface{} (http://godoc.org/labix.org/v2/mgo/bson#M)

    So, in

    conditions["publishdate"]["$gte"] = fromDate.Unix()
    

    You need to do a type assertion from interface{} to bson.M when looking up publishdate in the map.

    Instead, you could refactor the code to something like

    publishdate:= bson.M{}
    // ... your logic goes here
    conditions["publishdate"] = publishDate
    

    to save on unnecessary map lookups and type assertions.

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论

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