linux下如何提取bson中的MongoDB唯一标识_id

已经通过mongoc_collection_find()和mongoc_cursor_next()拿到想要的bson_t 类型对象现在想提取该对象中包含的MongoDB唯一标识_id。
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3个回答

自己找了一个笨方法实现了。

转成json,然后用_id做key来访问对应的数据

 while (mongoc_cursor_more (cursor) && mongoc_cursor_next (cursor, &doc)) {
      str = bson_as_json (doc, NULL);
      printf ("%s\n", str);
      bson_free (str);
   }
qq_33672112
半英里外的雨 您的意思是不是对C指针str做键值对"key=value"字符串,然后解析出_id的值
接近 2 年之前 回复
qq_33672112
半英里外的雨 具体如何转为json对象,您写的str应该是一个字符指针。因为初学,请多包涵。
接近 2 年之前 回复
oyljerry
oyljerry 回复qq_33672112: 转成json对象,然后_id是key
接近 2 年之前 回复
qq_33672112
半英里外的雨 我写的代码和您给的差不多,我想要的是如何从str里提取_id信息,或者从doc提取_id信息,您说的用_id做key具体怎么做,请指教。
接近 2 年之前 回复
 bson_t query;
bson_t child;
bson_init(&query);

BSON_APPEND_INT64(&query, "id", 0);

mongoc_cursor_t m_pCursor = mongoc_collection_find(m_pCollection,
    MONGOC_QUERY_NONE,
    0,
    0,
    0,
    &query,
    NULL,  /* Fields, NULL for all. */
    NULL); /* Read Prefs, NULL for default */

bson_destroy(&query);
bson_error_t error;
if (mongoc_cursor_error(m_pCursor, &error)) {
    cout << "Query Failure: " << error.message;
    return;
}

const bson_t *doc;

while (!mongoc_cursor_error(m_pCursor, &error)
    && mongoc_cursor_more(m_pCursor))
{
    if (mongoc_cursor_next(m_pCursor, &doc))
    {
        GetRecord(doc);
    }
    else
    {
        break;
    }
}
if (mongoc_cursor_error(m_pCursor, &error)) {
    cout << "Query Failure: " << error.message;
}

mongoc_cursor_destroy(m_pCursor);
qq_33672112
半英里外的雨 回复dabocaiqq: GetRecord函数是要引用哪个头文件还是自己定义的,另外记录中包含的_id怎么提取。请指教
接近 2 年之前 回复
dabocaiqq
穷在人世中少你左右我想我连什么价值也没有 回复qq_33672112: 获取文档的记录
接近 2 年之前 回复
qq_33672112
半英里外的雨 GetRecord(doc);起到什么作用
接近 2 年之前 回复
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<div class="post-text" itemprop="text"> <p>So here is my question. I have an array which are stored the <code>_ids</code> of mongodbs objects. Whats the right way to retrieve them all in one query using the mgo and bson package?</p> <p>So if the array is like that: <code>ids:=["543d171c5b2c12420dd016","543d171c5b2dd016"]</code></p> <p>How we make the query ? I tried that but I know its wrong.</p> <pre><code>query := bson.M{"_id": bson.M{"$in": ids}} c.Find(query).All() </code></pre> <p>Thanks in advance</p> </div>

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<div class="post-text" itemprop="text"> <p>Am trying to write the golang bson query for this mongodb query but cannot. Can anyone help? I can query mongo shell with the command</p> <pre><code>db.collection.find({"nfType": "SMF"},{"_id": 0,"ipv4Addresses": 1}) </code></pre> <p>which gives the output that i want as</p> <pre><code>[{ "ipv4Addresses": ["198.51.100.1"]}] </code></pre> <p>Now am trying to write a golang bson for this query to get only the ipv4Addresses field as shown above but cannot. The document in the collection is of the form</p> <pre><code>{ "nfType": [ "SMF" ], "nfStatus": [ "REG" ], "sNssais": [ { "sst": 1, "sd": "sd1" } ], "nsiList": [ "NSI-ID1" ], "ipv4Addresses": [ "198.51.100.1" ] } </code></pre> </div>

golang mongodb(mgo)未插入文档

<div class="post-text" itemprop="text"> <p>Im having issues with persisting a golang struct in mongodb using mgo. </p> <pre><code>type AN_Track_Log struct { Id bson.ObjectId `bson:"_id,omitempty"` user_session_id_str string `bson:"user_session_id_str"` googleanaly_pixel_id_str string `bson:"googleanaly_pixel_id_str"` perfaud_pixel_id_str string `bson:"perfaud_pixel_id_str"` site_id_str string `bson:"site_id_str"` metric_str string `bson:"metric_str"` value_str string `bson:"value_str"` event_str string `bson:"event_str"` location_id_str string `bson:"location_id_str"` referer_str string `bson:"referer_str"` track_origin_str string `bson:"track_origin_str"` fingerprint_str string `bson:"fingerprint_str"` ... } p_track_log.Id = bson.NewObjectId() err := p_mongodb_coll.Insert(&amp;p_track_log) </code></pre> <p>the problem is that when the Insert() call completes, the only thing thats persisted in the DB is an empty doc</p> <pre><code>{u'_id': ObjectId('561809d20037873154000003')} </code></pre> <p>I check that the struct fields are indeed set, and not empty. Any ideas as to why this is happening. Hints are appreciated :) thank you</p> </div>

如何结合bson.M过滤器

<div class="post-text" itemprop="text"> <p>I am trying to combine some filters with no success. I am using the mongodb driver for go</p> <pre><code>// FindOneByID returns an error on fail, otherwise, it sets the {out} by the result. func FindOneByID(collectionName string, id *primitive.ObjectID, out interface{}, considerArchivedItems bool) error { ctx, _ := context.WithTimeout(context.Background(), 2*time.Second) var filter bson.M if considerArchivedItems { filter = bson.M{"_id": id} } else { filter = bson.M{"$and": bson.A{ bson.M{"_id": id}, bson.M{isArchived: bson.M{"$ne": false}}}} } return database.Collection(collectionName).FindOne(ctx, filter).Decode(out) } </code></pre> <p>Now, I insert an object as archived and trying to get the document. The document is inserted as archived, so I want to consider archived items.</p> <p>However, when I pass in the <code>else</code>, document can be either archived or not (<code>false</code> or <code>true</code>), I still get it anyway. So it means that my $and doesn’t work..</p> <pre><code>const ( databaseNameUnitTests = "database_name_unit_tests" databaseCollectionNameUnitTests = "database_name_unit_tests" ) type Test struct { ID *primitive.ObjectID `protobuf:"bytes,1,opt,name=id,proto3" json:"_id,omitempty" bson:"_id,omitempty"` IsArchived bool `protobuf:"varint,2,opt,name=IsArchived,proto3" json:"is_archived,omitempty" bson:"is_archived,omitempty"` Description string `protobuf:"varint,3,opt,name=Description,proto3" json:"description,omitempty" bson:"description,omitempty"` } // func var item Test err := mongodb.FindOneByID(databaseCollectionNameUnitTests, insertedID, &amp;item, false) </code></pre> <p>The following query from Robo 3T : <code>db.getCollection('database_name_unit_tests').find({$and:[{"_id":ObjectId("5d2e8afeb0e106fbe0d5af21")},{"is_archived": {$ne:false}}]})</code> this works tho, where am I wrong?</p> </div>

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<div class="post-text" itemprop="text"> <p>I'm working with <a href="https://github.com/mongodb/mongo-go-driver" rel="nofollow noreferrer">https://github.com/mongodb/mongo-go-driver</a> and currently trying to implement a partial update of such struct</p> <pre><code>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"` } </code></pre> <p>For instance, if I have</p> <pre><code>noteUpdate := NoteUpdate{ Title: "New Title" } </code></pre> <p>Then I expect that the only "title" field in the stored document will be changed.</p> <p>I need to write something like</p> <pre><code>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("$set", bson.NewDocument(...))) ) </code></pre> <p>The problem is that I don't want to manually encode each non-empty field with <code>bson.EC.String(...)</code> or <code>bson.EC.Int64(...)</code>. I tried to use <code>bson.EC.InterfaceErr(...)</code> but got an error </p> <blockquote> <p>Cannot create element for type *models.NoteUpdate, try using bsoncodec.ConstructElementErr</p> </blockquote> <p>Unfortunately, there is no such function in bsoncodec. The only way I found is to create wrapper </p> <pre><code>type SetWrapper struct { Set interface{} `bson:"$set,omitempty"` } </code></pre> <p>And use it like</p> <pre><code>partialUpdate := &amp;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, ) </code></pre> <p>It works, but is it possible to achieve the same with bson/bsoncodec document builders ?</p> <p>UPD. The full context of my question: I wrote the REST endpoint for <strong>partially</strong> updating "Note" documents(stored in MongoDB). Code that I have now:</p> <pre><code>var noteUpdate models.NoteUpdate ctx.BindJSON(&amp;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), ) </code></pre> <p>Code that I want to have</p> <pre><code>var noteUpdate models.NoteUpdate ctx.BindJSON(&amp;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("$set", &amp;noteUpdate)), ), findopt.OptReturnDocument(option.After), ) </code></pre> <p>Code that I <strong>don't</strong> want to have</p> <pre><code>var noteUpdate models.NoteUpdate ctx.BindJSON(&amp;noteUpdate) //omit validation and errors handling bsonNote := bson.NewDocument() if noteUpdate.Title != "" { bsonNote.Append(bson.EC.String("title", noteUpdate.Title)) } if noteUpdate.Content != "" { bsonNote.Append(bson.EC.String("content", noteUpdate.Content)) } //..setting the rest of the fields... res := collection.FindOneAndUpdate( context.Background(), bson.NewDocument(bson.EC.String("_id", noteUpdate.ID)), bson.NewDocument(bson.EC.SubDocument("$set", bsonNote)), findopt.OptReturnDocument(option.After), ) </code></pre> <p>So, the precise question is - is there any way to build *bson.Document dynamically based on <code>bson</code> tags(without predefined wrappers like my SetWrapper)? </p> </div>

在MongoDB和Golang的查询参考中获取值

<div class="post-text" itemprop="text"> <p>I have the structures below. I use <strong>Golang 1.9.2</strong>.</p> <pre><code>// EventBoost describes the model of a EventBoost type EventBoost struct { ID string `bson:"_id" json:"_id" valid:"alphanum,printableascii"` CampaignID string `bson:"_campaign_id" json:"_campaign_id" valid:"alphanum,printableascii"` Name string `bson:"name" json:"name"` Description string `bson:"description" json:"description"` Level string `bson:"level" json:"level"` EventID string `bson:"_event_id" json:"_event_id" valid:"alphanum,printableascii"` StartDate time.Time `bson:"start_date" json:"start_date"` EndDate time.Time `bson:"end_date" json:"end_date"` IsPublished bool `bson:"is_published" json:"is_published"` CreatedBy string `bson:"created_by" json:"created_by"` CreatedAt time.Time `bson:"created_at" json:"created_at"` ModifiedAt time.Time `bson:"modified_at" json:"modified_at"` } // LocationBoost describes the model of a LocationBoost type LocationBoost struct { ID string `bson:"_id" json:"_id" valid:"alphanum,printableascii"` CampaignID string `bson:"_campaign_id" json:"_campaign_id" valid:"alphanum,printableascii"` Name string `bson:"name" json:"name"` Description string `bson:"description" json:"description"` Level string `bson:"level" json:"level"` LocationID string `bson:"_location_id" json:"_location_id" valid:"alphanum,printableascii"` StartDate time.Time `bson:"start_date" json:"start_date"` EndDate time.Time `bson:"end_date" json:"end_date"` IsPublished bool `bson:"is_published" json:"is_published"` CreatedBy string `bson:"created_by" json:"created_by"` CreatedAt time.Time `bson:"created_at" json:"created_at"` ModifiedAt time.Time `bson:"modified_at" json:"modified_at"` } // Campaign describes the model of a Campaign type Campaign struct { ID string `bson:"_id" json:"_id" valid:"alphanum,printableascii"` Name string `bson:"name" json:"name"` Description string `bson:"description" json:"description"` EventBoostIDs []string `bson:"event_boost_ids" json:"event_boost_ids"` LocationBoostIDs []string `bson:"location_boost_ids" json:"location_boost_ids"` StartDate time.Time `bson:"start_date" json:"start_date"` EndDate time.Time `bson:"end_date" json:"end_date"` IsPublished bool `bson:"is_published" json:"is_published"` CreatedBy string `bson:"created_by" json:"created_by"` CreatedAt time.Time `bson:"created_at" json:"created_at"` ModifiedAt time.Time `bson:"modified_at" json:"modified_at"` } </code></pre> <p>A <strong>Campaign</strong> (understand a marketing campaign) is made of <strong>Events</strong> or <strong>Locations</strong> that can be boosted with a level (basic or premium). A campaign has a start and a end date, so do have the boosts.</p> <p>The function <code>GetEventLevel</code> has to return me the level of a given event.</p> <pre><code>// GetEventLevel of an event func (dao *campaignDAO) GetEventLevel(eventID string) (string, error) { } </code></pre> <p>If the event is boosted in <em>an active campaign</em> (<code>isPublished</code> is <code>true</code>), and <em>the boost is active</em> (<code>isPublished</code> is <code>true</code>) and <em>the now date is between the start and end date of the boost</em>, then my Event is <strong>boosted</strong>, so the function returns the level (basic or premium). Else, it returns <code>"standard"</code>.</p> <p>My question is : <strong>can I do this fully with Mongo ? Or do I need to perform some logic in the DAO with Golang ?</strong></p> <p>If I can do this with Mongo, what I hope, I have no idea how to do this. From what I understand, I would first need to lookup the events and the locations of the campaign, and then search in it with dates, but..</p> </div>

使用bson的golang结构默认值

<div class="post-text" itemprop="text"> <p>I looking return default value for new struct, without value, this is my current struct :</p> <pre><code>// Campaign represents a email campaign type Campaign struct { ID bson.ObjectId `json:"id" bson:"_id"` CampaignName string `json:"campaign_name" bson:"campaign_name"` FromName []string `json:"from_name" bson:"from_name"` FromEmail string `json:"from_email" bson:"from_email"` ReplyEmail string `json:"reply_email" bson:"reply_email"` Subject []string `json:"subject" bson:"subject"` BodyText string `json:"body_text" bson:"body_text"` BodyHTML string `json:"body_html" bson:"body_html"` SMTPList bson.ObjectId `json:"smtp_list" bson:"smtp_list"` EmailList bson.ObjectId `json:"email_list" bson:"email_list"` DateCreated time.Time `json:"date_created" bson:"date_created"` DateUpdated time.Time `json:"date_updated" bson:"date_updated"` DateSendFinish time.Time `json:"date_send_finish" bson:"date_send_finish"` OwnerID bson.ObjectId `json:"owner_id" bson:"owner_id"` Opens int `json:"opens" bson:"opens"` Clicks int `json:"clicks" bson:"clicks"` Status string `json:"status" bson:"status"` } </code></pre> <p>I want to return Status = "draft" How i can do this ?</p> </div>

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