mgo find将单个值数组转换为字符串

This is part of my collection schema in mongodb:

{ "_id" : ObjectId("55e1eef5255da6d384754642"), "name" : [ "Web, Mobile & Software Dev", "Movil y desarrollo de software" ] } { "_id" : ObjectId("55e1f2d0255da6d38475464b"), "name" : [ "IT & Networking", "TI y Redes" ] } ...

Right now i can get the info like this:

 err := r.Coll.Find(bson.M{}).Select(bson.M{"name": bson.M{"$slice": []int{1, 1}}}).All(&result.Data)

but i want "name" to return a string instead of a single value array, so i dont have to index it inside my frontend if no need.

dpp80346 所以我将不得不循环并自己为所有记录更改它吗?是不是像一个带字符串的concat数组变成字符串或强制转换之类的东西,确定吗?
接近 5 年之前 回复


very limited comments i need 2000 poits for editing my post and add more things it seems, this is not answer but maybe, so i have to loop it?, isnt better way?

err := r.Coll.Find(bson.M{}).Select(bson.M{"name": bson.M{"$slice": []int{1, 1}}}).All(&result.Data)                                            
  if err != nil {                                                                                                                                 
      return result, err                                                                                                                          

  type skillnew struct {                                                                                                                          
      Id   bson.ObjectId `json:"id,omitempty" bson:"_id,omitempty"`                                                                               
      Name string        `bson:"name,omitempty" json:"name,omitempty"`                                                                            

  skillsallnew := make([]skillnew, len(result.Data))                                                                                              
  for i := range result.Data {                                                                                                                    
      skillsallnew[i] = skillnew{result.Data[i].Id, result.Data[i].Name[0]}                                                                       
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<div class="post-text" itemprop="text"> <p>I have an element that looks like this:</p> <pre><code>{"Name":"test name","DBType":0,"UserName":"test user","Password":"","Host":"test host","Port":"123","DBName":"test schema","Options":"test options","Groups":["test1"]} </code></pre> <p>I want to be able to query the cataloug of Datasources for those which are assigned to a particular group.</p> <p>My code for this is:</p> <pre><code>var d []Source q := bson.M{"Groups": bson.M{"$in": [1]string{groupName}}} findErr := c.Find(q).All(&amp;d) </code></pre> <p>However - I get no error and no results.</p> <p>I've also tried</p> <pre><code>q := bson.M{"Groups": groupName} </code></pre> <p>with the same result.</p> <pre><code>//Source describes a data source type Source struct { Name string DBType uint UserName string Password string Host string Port string DBName string Options string Groups []string } </code></pre> <p>I'm stuck - I am puzzled! Any help appreciated.</p> <p>Update - I tried</p> <pre><code>{"Name":"test name"} </code></pre> <p>and this returns 0 items. Yet if I set to nil I get stuff.</p> </div>


<div class="post-text" itemprop="text"> <p>I am having difficulty converting a MongoDB query to mgo bson. The Mongo record schema is as shown below. I want to find records that have topics with label "Education" and "Students".</p> <pre><code>db.questions.insert ( { "_id" : ObjectId("5cb4048478163fa3c9726fdf"), "questionText" : "why?", "createdOn" : new Date(), "createdBy": user1, "topics" : [ { "label": "Education", }, { "label": "Life and Living", }, { "label": "Students" } ] } ) </code></pre> <p>Using Robo 3T, the query looks like this:</p> <pre><code>db.questions.find({$and : [ {"topics": {"label": "Students"}}, {"topics": {"label": "Education"}} ]}) </code></pre> <p>I am having trouble modeling this with MGO. Currently, have tried this:</p> <pre><code>map[$and:[ map[topics:map[label:students]] map[topics:map[label:life and living]] ]] </code></pre> <p>and this</p> <pre><code>map[topics:map[$and:[ map[label:students] map[label:life and living] ]]] </code></pre> </div>

mongo 时间转换,管道语句查询的时候将long型转换为日期字符串

图中capturetime 是number型,例如值为1501540000,转化为time 类型为日期字符串,比如2017-09-14![图片](


<div class="post-text" itemprop="text"> <p>I have following mongodb (3.4.x) document, i code in golang with mgo driver</p> <pre><code>{ "id": "5981d4c2795a1b4a801ee027", "scenarioId": "59804b10d8ee910085e33865", "messages": [ { "id": "5981d4c2795a1b4a801ee028", "toQueue": [ { "id": "5981d4c2795a1b4a801ee029", "to": { "email": "" }, "channel": "EMAIL", "toType": "EMAIL", "status": { "id": 1, "groupId": 1, "groupName": "PROCESSING", "name": "APPROVED", "description": "MessageChain approved for processing" } }, { "id": "5981d4c2795a1b4a801ee02a", "to": { "phone": "+381631891245" }, "channel": "SMS", "toType": "PHONE", "status": { "id": 1, "groupId": 1, "groupName": "PROCESSING", "name": "APPROVED", "description": "MessageChain approved for processing" } } ], "status": { "id": 1, "groupId": 1, "groupName": "PROCESSING", "name": "APPROVED", "description": "MessageChain approved for processing" } }, { "id": "5981d4c2795a1b4a801ee02b", "toQueue": [ { "id": "5981d4c2795a1b4a801ee02c", "to": { "phone": "+123456789" }, "channel": "SMS", "toType": "PHONE", "status": { "id": 1, "groupId": 1, "groupName": "PROCESSING", "name": "APPROVED", "description": "MessageChain approved for processing" } } ], "status": { "id": 1, "groupId": 1, "groupName": "PROCESSING", "name": "APPROVED", "description": "MessageChain approved for processing" } } ], "messageStages": [ { "id": "5981d4c2795a1b4a801ee033", "validityPeriod": 5, "validityPeriodTimeUnit": "MINUTES", "providerId": 5, "email": { "text": "this is the email text", "subject": "and here the email subject" }, "status": { "id": 1, "groupId": 1, "groupName": "PROCESSING", "name": "APPROVED", "description": "MessageChain approved for processing" } } ] </code></pre> <p>}</p> <p>and I know the value of messages.$, where i want to update in the related toQueue Array Item.</p> <p>I tried to do it that way:</p> <pre><code>query = bson.M{ "messages.toQueue._id": toQueueId, } update = bson.M{ "$set": bson.M{ "messages.$.toQueue.$": status.Id, "messages.$.toQueue.$": status.Name, "messages.$.toQueue.$.status.groupId": status.GroupId, "messages.$.toQueue.$.status.groupName": status.GroupName, "messages.$.toQueue.$.status.description": status.Description, }, } err = cr.Update(query,update) </code></pre> <p>but multiple $ are not allowed. Without it's also not updateable.</p> <p>Is there any way to update only the subdocument, which i found in query ?</p> </div>

Golang,MongoDB,使用$ in在数组属性中查找带有一个字符串的所有元素时遇到问题

<div class="post-text" itemprop="text"> <p>I am trying to find all users in a MongoDB collection that contains a username string in the friends array. I am using Golang with the mgo driver. </p> <pre><code> type User struct { ... Friends []string `json: friends bson:"friends,omitempty"` ... } ... // username is a string arr := []string{username} err := c.Find(bson.M{"friends": {"$in": arr}}).All(&amp;users) ... </code></pre> <p>I get this error: http: panic serving [::1]:56358: assignment to entry in nil map</p> <p>Any help would be greatly appreciated.</p> </div>

在文档mongodb mgo驱动程序中的嵌套数组上增加特定值

<div class="post-text" itemprop="text"> <p>Here is my mongo collection in json :</p> <pre><code>"messages" : { "_id" : ObjectId("5c26844696b72e4b6c9ceee7"), "pointer" : ObjectId("5c26844696b72e4b6c9ceee6"), "messages" : [ { "uuid" : "f03f7977-0b4e-11e9-9f95-144fd7c03810", "content" : "Hello", "reportedTimes":0 }, { "uuid" : "78bb831d-0b57-11e9-a286-144fd7c03810", "content" : "Yes", "reportedTimes":0 } ] } </code></pre> <p>I would like to update the "reportedTimes" value from a "pointer" and a "uuid". I tried many aggregations but without result like that one :</p> <pre><code>pipe := []bson.M{bson.M{"$match": bson.M{"pointer": knownPointer}}, {"messages": bson.M{"$match": bson.M{"uuid": knownUUID}}}, {"$inc": bson.M{"messages.$.reportedTimes": 1}}} </code></pre> <p>That one returns that I cannot use "$inc"</p> <p>or that one </p> <pre><code>pipe := []bson.M{{"$match": bson.M{"pointer": knownPointer}}, {"$unwind": "$messages"}, {"$project": bson.M{"uuid": "$messages.uuid", "reportedTimes": "$messages.reportedTimes"}}, {"$match": bson.M{"uuid": knownUuid}}} then inc. </code></pre> <p>I even don't find all my attempts queries... I'm completely stuck... I also tried with Update(selector, query) but still cannot find the working and efficient way to do it. A little help would be appreciated. Thanks all.</p> </div>

使用mgo Golang从MongoDB子文档数组中解组

<div class="post-text" itemprop="text"> <p>I am trying to figure out how to get a single subdocument from an array and unmarshal it into a struct.</p> <p>My mongo document looks like this: </p> <pre><code>{ "_id" : ObjectId("abc123"), "gamecode" : "abc123" "players" : [ { "playerid" : ObjectId("abc123"), "username" : "test", }, { "playerid" : ObjectId("abc456"), "username" : "test2" }] } </code></pre> <p>And I have a player struct that looks like this:</p> <pre><code>type Player struct { PlayerID bson.ObjectId `bson:"playerid" json:"playerid"` Username string `bson:"username" json:"username"` } </code></pre> <p>From the mongo command line I can do a </p> <pre><code>{"players.playerid": ObjectId('abc123')}, {"_id": 0, "players.$":1}) </code></pre> <p>Which returns </p> <pre><code>{"players" : [{ "playerid" : ObjectId("abc123"), "username" : "test"}]} </code></pre> <p>But I am having a hard time figuring out how to implement this same functionality in Go so that I have a populated player struct from the result of the query. I have been playing around with different configurations of the code below, but it always results in an empty struct. What am I missing here?</p> <pre><code>player := Player{} collection.Find(bson.M{"players.playerid": bson.ObjectIdHex(pid)}).Select(bson.M{"_id": 0, "players.$": 1}).One(&amp;player) </code></pre> <p>I am running the latest MongoDB version and am using the mgo.v2 driver for Go.</p> </div>


<div class="post-text" itemprop="text"> <p>I was wondering, is there anyway to run my own command (or query) which I have constructed as a string variable using "mgo" in go. </p> <p>Something like this:</p> <pre><code>c := session.DB(DBNAME).C(COLLECTION) c.RUN_COMMAND_AS_STRING("find({username:'vahid'})") </code></pre> </div>

mgo $ all使用数组查询数组并且不区分大小写?

<div class="post-text" itemprop="text"> <p>I have an array of ingredient names that is dynamic and provided per user. I'd like to match it to <code>mongo</code> documents where there is an <code>array</code> of objects called <code>ingredients</code> which has a property <code>name</code>. I've written a query (see below) which will take query parameters from the URL and will return all the documents that have all matching ingredient names, however this search is case sensitive and I'd like it not to be. </p> <p>I've considered using <code>bson.RegEx</code> with <code>Option: "i"</code>, however I'm not sure how to form this query or apply it to an array of strings.</p> <p>Here is the case sensitive query:</p> <pre><code>// Check for ingredients, return all recipes that can be made using supplied ingredients if qryPrms["ingredients"] != nil { mongodQ[""] = bson.M{"$all": qryPrms["ingredients"]} } </code></pre> <p><code>mongodQ</code> is the <code>bson.M</code> I use to query the collection later in the code. Ideally I could apply <code>RegEx</code> to each element in <code>qryPrms["ingredients"]</code> so it would return closely matching ingredients like <code>cheese</code> would return <code>swiss cheese</code> as well. This is also a more general <code>mongodb</code> question I suppose when it comes to querying with a dynamic array.</p> </div>


<div class="post-text" itemprop="text"> <p>I want to do a multi-level array element delete. My Structs are as follows:-</p> <pre><code>type Company struct { Id bson.ObjectId `bson:"_id,omitempty"` CompanyName string Process []ProcessItem } type ProcessItem struct{ SortOrder int Documents []DocumentTemplate } type DocumentTemplate struct { Id bson.ObjectId `bson:"_id,omitempty"` TemplateName string } </code></pre> <p>I want to delete an object of type DocumentTemplate. The DocumentTemplate is a struct array in ProcessItem which is a struct array in Company struct. I have Company Id(field of struct Company) and TemplateName(field of struct DocumentTemplate).</p> <p>I tried the below mgo pull query but it is not working.</p> <pre><code>c := db.C("company") pullQuery := bson.M{"process": bson.M{"documents.templatename": "xyz"}} err := c.Update(bson.M{"_id": "123"}, bson.M{"$pull": pullQuery}) </code></pre> <p>Please point out the mistakes I made here. Thanks.</p> <p><strong>Edit:</strong> Adding one example document for the clarity of the question</p> <pre><code>{ "_id" : ObjectId("573da7dddd73171e42a84045"), "companyname" : "AAA", "process" : [ { "processname" : "Enquiry", "sortorder" : 0, "documents" : [ { "templatename" : "xyz", "processname" : "Enquiry" }, { "templatename" : "ss", "processname" : "Enquiry" } ] }, { "processname" : "Converted", "processtype" : 1, "sortorder" : 2, "documents" : [ { "templatename" : "dd", "processname" : "Converted" }, { "templatename" : "fg", "processname" : "Converted" } ] } ] } </code></pre> <p>I need to pull out just one DocumentTemplete record, like the one below:</p> <pre><code>{ "templatename" : "xyz", "processname" : "Enquiry" } </code></pre> <p>N.B: TemplateName will be unique inside a Company.</p> </div>


<div class="post-text" itemprop="text"> <p>So recently I've been trying to insert different types of data into structures using mgo, and I've ran into a bit of a snag. When trying to insert an array of object IDs, I can't seem to figure out that format if I were to populate that object ID array within the structure.</p> <p>Here's the structure as follows</p> <pre><code>type Group struct { ID bson.ObjectId `json:"id" bson:"_id"` GroupName string `json:"groupName"` UserIDs []*bson.ObjectId `json:"users" bson:"userid"` Expected []*int `json:"expected"` Actual []*int `json:"actual"` } </code></pre> <p>And the operation I am trying to run is to insert a new "test" table with a single userID into UserIDs.</p> <pre><code>array := []*bson.ObjectId{&amp;findJ.ID} c = Session.DB("test").C("Group") err = c.Insert(&amp;Group{GroupName: "test", UserIDs: array}) ThisPanic(err) </code></pre> <p>Where findJ has it's own ID from a separate structure. What am I doing wrong here, as it is causing a panic on inserting the array.</p> </div>


<div class="post-text" itemprop="text"> <p>My json looks like the following,</p> <pre><code>[ { "key1": 1, "key2": "val2" }, { "key1": 2, "key2": "val2" } ] </code></pre> <p>This json comes in string format and I want the objects in the json array to be inserted as individual records in mongodb. I referred to <a href="" rel="nofollow"></a> but wasn't able to find enough examples on the above use-case. Appreciate your thoughts in finding a solution.</p> </div>

从mgo GridFile提取ID的字符串值

<div class="post-text" itemprop="text"> <p>Being quite new to Go, I am having a hard time using mgo. I am using mgo to fetch files like this :</p> <pre><code>gridfs := db.GridFS("fs") allFiles := gridfs.Find(nil).Iter() </code></pre> <p>And then I use the returned iterator like </p> <pre><code> var f *mgo.GridFile for gridfs.OpenNext(allFiles, &amp;f) { //use f.Id() } </code></pre> <p>I want to start using f.Id() as a String but I am unable to convert. One of the ways I found was by using <code>fileId := (f.Id().(bson.ObjectId)).Hex()</code> which just lets me compile but fails at runtime with the message <code>interface conversion: interface {} is bson.ObjectId, not bson.ObjectId</code></p> <p>Having spent a lot of time on this already, I am definitely open to changing the way I fetch the files if conversion is not possible using <code>GridFile</code>. I would appreciate any help with this. Thanks.</p> </div>

mgo.v2 Find()。Select()。One()返回空白

<div class="post-text" itemprop="text"> <p>The mongo shell output</p> <pre><code>&gt; db.departments.find() { "_id" : ObjectId("5733b051e444917f9d273ce6"), "id" : "5733b05157659a11a4589102", "brandid" : "1", "name" : "first", "managerid" : "0", "users" : [ "1", "2", "3", "7" ] } </code></pre> <p>The function takes depID as input which I verified is exactly what it should be i.e. <code>5733b05157659a11a4589102</code></p> <pre><code>func GetUsers(depID string) (*department.UsersResp, error) { if !bson.IsObjectIdHex(depID) { return nil, fmt.Errorf("%s is not a ObjectId value", depID) } type UserResp struct { users []string } var result *UserResp err := coll.Find(bson.M{"id": depID}).Select(bson.M{"users": 1}).One(&amp;result) if err != nil { fmt.Println(err, result) return nil, err } fmt.Println("result:",result) //ignore return type and value the above print is what i have doubt about return result, nil } </code></pre> <p>the out put of result comes <code>{[]}</code></p> <p>i have tried the following queries other that above<br> <code>err := coll.Find(bson.M{"id": depID})One(&amp;result)</code><br> <code>err := coll.Find(nil).One(&amp;result)</code><br> the result is same.</p> <p>everything is fine with db connection and other things as all the other functions of the same file using the same variable <code>coll</code> works</p> <p><em>More Info</em> Also I have tried this</p> <pre><code>type UserResp struct { users []string `json:"users" bson:"users"` } </code></pre> <p>Mongo LOG</p> <pre><code>MGO: cluster.go:590: Cluster has 1 known masters and 0 known slaves. MGO: socket.go:391: Socket 0xc8201340e0 to serializing op: &amp;mgo.queryOp{collection:"departments.departments", query:bson.M{"id":"5733b05157659a11a4589102"}, skip:0, limit:-1, selector:bson.M{"users":1}, flags:0x4, replyFunc:(mgo.replyFunc)(0x58eef0), mode:1, options:mgo.queryWrapper{Query:interface {}(nil), OrderBy:interface {}(nil), Hint:interface {}(nil), Explain:false, Snapshot:false, ReadPreference:bson.D(nil), MaxScan:0, MaxTimeMS:0, Comment:""}, hasOptions:false, serverTags:[]bson.D(nil)} MGO: socket.go:521: Socket 0xc8201340e0 to sending 1 op(s) (106 bytes) MGO: socket.go:311: Socket 0xc8201340e0 to updated write deadline to 1m0s ahead (2016-05-12 10:18:17.811427695 -0400 EDT) MGO: socket.go:311: Socket 0xc8201340e0 to updated read deadline to 1m0s ahead (2016-05-12 10:18:17.811468447 -0400 EDT) MGO: socket.go:563: Socket 0xc8201340e0 to got reply (106 bytes) MGO: socket.go:622: Socket 0xc8201340e0 to received document: bson.M{"_id":"W3\xb0Q\xe4D\x91\u007f\x9d'&lt;\xe6", "users":[]interface {}{"1", "2", "3", "7"}} MGO: session.go:3062: Query 0xc82012c000 document unmarshaled: &amp;db.UserResp{users:[]string(nil)} {[]} </code></pre> </div>


<div class="post-text" itemprop="text"> <p>I have this document inside my database</p> <pre><code>[ { "_id": "53dc97bf91f1f933e15d6fb1", "attributes": { "chilled": false, "flammable": false, "food": false, "fragile": false, "frozen": false, "hot": false, "outsized": false }, "createdAt": "02/08/14 09:48:16", "customer": "53d68bc091f1f933e15d6f90", "location": [ { "count": 0, "warehouse": "53db430c91f1f933e15d6fa6" }, { "count": 34, "warehouse": "53db430c91g1f933e45d6fa4" }, ], "name": "test", "type": "stored", "updatedAt": "" } ] </code></pre> <p>How can i update the location array if i know the warehouse Id? This is what i have now</p> <pre><code>coll := p.GetDb().C("product") changes := bson.M { "location": bson.M { "$elemMatch": bson.M { "warehouse": bson.ObjectIdHex(warehouseId), }, }, "$set": bson.M { "location.$.count": 4, }, } err := coll.UpdateId(bson.ObjectIdHex(productId), changes) if err != nil { http.Error(res, err.Error(), 500) return } </code></pre> <p>But get this error: The dollar ($) prefixed field '$elemMatch' in 'location.$elemMatch' is not valid for storage.</p> <p>thx.</p> </div>


<div class="post-text" itemprop="text"> <p>I have the following function in my API in order to check a user owns a related document</p> <pre><code>type User struct { Id bson.ObjectId `bson:"_id,omitempty" json:"id"` Name string `form:"name" bson:"name,omitempty" json:"name,omitempty"` Password string `form:"password" bson:"password,omitempty" json:"-" binding:"required"` Email string `form:"email" bson:"email,omitempty" json:"email" binding:"required"` Artists []bson.ObjectId `form:"artists" bson:"artists,omitempty" json:"artists" inline` ContentFeed []bson.ObjectId `form:"content_feed" bson:"content_feed,omitempty" json:"content_feed" inline` Location string `form:"user_location" bson:"user_location,omitempty" json:"user_location,omitempty"` TopTracks []bson.ObjectId `form:"top_tracks" bson:"top_tracks" json:"top_tracks" inline` Avatar string `form:"avatar" bson:"avatar,omitempty" json:"avatar,omitempty"` BgImg string `form:"bg_img" bson:"bg_img,omitempty" json:"bg_img,omitempty"` } // Get artist // This doesn't actual get the full artist object, this just checks that // the artist id given is stores against the given users list of artists func (repo *UserRepo) GetArtist(user string, artist string) (bool, error) { userData := &amp;User{} fmt.Println(user) err := repo.collection.Find(bson.M{"_id": user, "artists": bson.M{"$in": []bson.ObjectId{bson.ObjectIdHex(artist)}}}).One(&amp;userData) if err != nil { fmt.Println(err) return false, err } return true, err } </code></pre> <p>However it returns an error which prints 'not found', despite giving it two ID's which definitely exist and are related when I inspect the list of artist id's for that given user. </p> </div>

构建同时包含字符串和正则表达式模式的$ in数组

<div class="post-text" itemprop="text"> <p>I have a Mongo collection where every document in the collection has a sources array property. Searches on this property can be a combination of exact matches and regex. For example, when using Mongo shell, the query below searches for documents with source='gas valves' OR 'hose' is contained in source item. This works just as I expect</p> <pre><code>db.notice.find({sources:{$in:[/\bhose/i,'gas valves']}}) </code></pre> <p>Things get a little trickier in mgo. Because some items in the $in array can be regex, and the others strings - the only way I have figured to make a query is by using $or:</p> <pre><code>var regEx []bson.RegEx var matches []string // do stuff to populate regEx and matches filter["$or"] = []bson.M{ {"sources":bson.M{"$in":regEx}}, {"sources":bson.M{"$in":matches}}, } </code></pre> <p>Is there some way I could construct one slice with both regex and string to use with $in - eliminating the need for the $or</p> </div>


<div class="post-text" itemprop="text"> <p>Here below I have document structure designed as follows:</p> <pre><code>type MIS_Course struct { ID bson.ObjectId `bson:"_id,omitempty"` Name string `bson:"crse_name"` } type MIS_Department struct { ID bson.ObjectId `bson:"_id,omitempty"` Name string `bson:"dept_name"` Courses []MIS_Course `bson:"crse_list"` } type MIS_School struct { ID bson.ObjectId `bson:"_id,omitempty"` Name string `bson:"school_name"` Departments []MIS_Department `bson:"dept_list"` } </code></pre> <p>And when initialized, I would have a "School ABC" in a sea of schools containing something that looks like below:</p> <pre><code>{ "_id" : ObjectId("55fbb522022aae7b3a000003"), "school_name" : "School ABC", "dept_list" : [ { "dept_name" : "Department A", "crse_list" : [ { "crse_name" : "Class A" }, { "crse_name" : "Class B" }, ] } ] } </code></pre> <p>For hours on end I couldn't find a solution that effectively works by given the school_name, dept_name, and crse_name:</p> <p>Find the <code>dept_list</code> of <code>school_name</code> &gt; find the <code>crse_list</code> of <code>dept_name</code> &gt; find <code>crse_name</code></p> <p>The reason that such chain of finds are required is because the scope of the find should be limited to the school, and then the department. Logic and housekeeping happens after the each stages of finds. </p> <p>I tried code such as</p> <pre><code>result := MIS_School{} err := database.C("schools").Find(bson.M{"school_name": school}).Select( bson.M{"dept_list": bson.M{"$elemMatch": bson.M{"dept_name": dept}}}).Select( bson.M{"crse_list": bson.M{"$elemMatch": bson.M{"crse_name": crse}}}).One(&amp;result) </code></pre> <p>But it didn't work since Select projections can't be chained in Mgo(?)</p> <p>I have read from somewhere that mongodb doesn't have the capability to directly retrieve documents nested in arrays deeper than 1-2 levels (Getting Document C inside B array inside A array). Is that true? How could I work around this problem?</p> <p>Thanks!</p> </div>


<div class="post-text" itemprop="text"> <p>Can we update sub-document array fields along with other document fields in Mgo? If so, please help me with my query.</p> <pre><code> c := db.C("user") colQuerier := bson.M{"email": *olduname} change := bson.M{"$set":bson.M{"password":*pwd, "place":*place, "emails.$.received":*received,"emails.$.sent":*sent}} err := c.Update(colQuerier, change) </code></pre> <p>My Database Structs are as follows:</p> <pre><code>type Emails struct{ Id bson.ObjectId `bson:"_id,omitempty"` Received string Sent string } type User struct { Id bson.ObjectId `bson:"_id,omitempty"` Email string Password string Place string Emails } </code></pre> <p>I am getting a run time error saying: The positional operator did not find the match needed from the query. Unexpanded update: emails.$.received</p> </div>








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技术大佬:我去,你写的 switch 语句也太老土了吧

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