在mongodb db中解析错误，插入到具有唯一索引的集合中 [英] Parsing error in mongodb db, insert to collection with unique index

问题描述

我在mongodb中有一个集合，其文件格式为:

I have a collection in mongodb with documents of the form:

{
    "user": "user1",
    "email: "[e-mail]",
}

其中用户"和电子邮件"字段是唯一的.我想在集合中插入新用户，同时检查两个值的唯一性.我可以使用mgo在golang中插入以下内容:

Where the fields "user" and "email" are unique. I want to insert a new user to the collection, while checking for uniqueness of both values. I can do an insert in golang with mgo like this:

session.SetSafe(&mgo.Safe{}) // ensure mgo waits for errors

user := struct{
    string `bson:"user"`
    string `bson:"email"`
}{
    "user1",
    "[e-mail]"
}

err := users.Insert(user) // where user is type *mgo.Collection

如果我打印err，它将输出insertDocument :: caused by :: 11000 E11000 duplicate key error index: kails.users.$name_1 dup key: { : "user1" }

If I print err it outputs insertDocument :: caused by :: 11000 E11000 duplicate key error index: kails.users.$name_1 dup key: { : "user1" }

是否有一种惯用的方式使用此错误来查找哪个值不是唯一的? (或者是否需要其他步骤?).使用正则表达式解析字符串感觉……是错误的.

Is there an idiomatic way to use this error to find which of the values wasn't unique?, if not both? (or are there other steps needed?). Parsing the string using a regexp feels... wrong.

如果无法使用该错误查找是否不是唯一的，那么"$ or"查询(检查唯一性)+插入是否有其他选择?

If it's not possible to use the error to find if not unique, are there any alternatives to an "$or" query (check for unique) + insert?

我已经阅读了 mgo文档，希望我不要错过任何重要的内容

I've read the mgo documentation, hope I didn't miss anything important.

推荐答案

http://godoc.org/labix .org/v2/mgo#IsDup

func IsDup(err error) bool

IsDup返回err是否通知重复的键错误，因为主键索引或辅助唯一索引已经具有具有给定值的条目.

IsDup returns whether err informs of a duplicate key error because a primary key index or a secondary unique index already has an entry with the given value.

例如

err := users.Insert(user) // where user is type *mgo.Collection
if err != nil {
    if mgo.IsDup(err) {
        // Is a duplicate key, but we don't know which one 
    }
    // Is another error
}

不幸的是，在可能存在多个唯一索引的情况下，似乎没有一种方法可以识别哪个值不是唯一的.

Unfortunately there does not appear to be a way to discern which value is not unique in the case where you might have several unique indexes in place.

尽管如此，您可以改为使用ID和Email而不是user和email的User结构. ID将在Mongo插入时自动生成，而Email将具有唯一索引.如果您不需要其他唯一索引，则可以放心地假设IsDup == true情况意味着只有重复的电子邮件地址.

You could instead have a User struct with ID and Email instead of user and email, though. ID would be auto-generated on insert by Mongo, and Email would have a unique index. Provided you didn't need any further unique indexes you could then safely assume that an IsDup == true case means that there's a duplicate email address only.

电子邮件地址是很好的用户名，因为它使用户无需记住;)

Email addresses are good usernames as it's one less thing for users to remember ;)

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