MongoDB&C++開發（四）bsoncxx::builder::stream::document的增刪改查操作__C++

2. mongocxx

續上一篇，接著看一下mongocxx中的檔案有些什麼。

先看一下基本的增刪改查操作： 2.1 connect.cpp 資料庫的連結

參見之前的部落格。 2.2 create.cpp 構造文檔並插入

構造一個文檔，插入資料庫中的一個collection。關於builder::stream::document的使用見同系列部落格之（三）。

#include <bsoncxx/builder/stream/document.hpp>#include <bsoncxx/types.hpp>#include <mongocxx/client.hpp>#include <mongocxx/instance.hpp>#include <mongocxx/uri.hpp>using bsoncxx::builder::stream::document;using bsoncxx::builder::stream::open_document;using bsoncxx::builder::stream::close_document;using bsoncxx::builder::stream::open_array;using bsoncxx::builder::stream::close_array;using bsoncxx::builder::stream::finalize;int main(int, char**) {    mongocxx::instance inst{};    mongocxx::client conn{mongocxx::uri{}};    auto db = conn["test"];    // TODO: fix dates    // @begin: cpp-insert-a-document    bsoncxx::document::value restaurant_doc =        document{} << "address" << open_document << "street"                   << "2 Avenue"                   << "zipcode"                   << "10075"                   << "building"                   << "1480"                   << "coord" << open_array << -73.9557413 << 40.7720266 << close_array                   << close_document << "borough"                   << "Manhattan"                   << "cuisine"                   << "Italian"                   << "grades" << open_array << open_document << "date"                   << bsoncxx::types::b_date{std::chrono::milliseconds{12323}} << "grade"                   << "A"                   << "score" << 11 << close_document << open_document << "date"                   << bsoncxx::types::b_date{std::chrono::milliseconds{121212}} << "grade"                   << "B"                   << "score" << 17 << close_document << close_array << "name"                   << "Vella"                   << "restaurant_id"                   << "41704620" << finalize;    // We choose to move in our document here, which transfers ownership to insert_one()    auto res = db["restaurants"].insert_one(std::move(restaurant_doc));    // @end: cpp-insert-a-document}

在資料庫test中的restaurant”表”（collection）中插入一個檔案restaurant_doc:

 {     "address" : {                     "street"   :"2 Avenue",                     "zipcode"  :"10075",                     "building" :"1480",                      "coord"    :[-73.9557413,40.7720266],                 },    "borough" : "Manhattan",    "cuisine" : "Italian",    "grades"  : [                    {                       "date"  : ***時間，                       “grade" : "A",                       "score" : 11                   }                   {                       "date"  : ***時間，                       ”grade" : "B",                       "score" : 17                   }               ]    "name"          : "Vella",    "restaruant_id" : "41706420"}

2.3 update.cpp 找到一個合格文檔，修改/建立一個索引值對 嵌套修改/建立一個索引值對 修改多個檔案中的索引值對 找到一個合格文檔，替換文檔中的一部分內容

int main(int, char**) {    mongocxx::instance inst{};    mongocxx::client conn{mongocxx::uri{}};    auto db = conn["test"];    // Update top-level fields in a single document.    {        // @begin: cpp-update-top-level-fields        //找到有"name":"Juni"索引值對的文檔，使用\$set指定一個          //鍵"cuisine"（如果文檔中沒有將建立），將這個索引值對改        //成"cuisine":"American(New)",然後使用\$currentDate指定        //叫做"lastModified"的鍵，bool值true表示這個鍵對應的值使用        //Date的形式（見此系列（2）中的常用資料類型        //使用Unix的時間格式記錄下當前的時間。        bsoncxx::builder::stream::document filter_builder, update_builder;        filter_builder << "name"                       << "Juni";        update_builder << "$set" << open_document << "cuisine"                       << "American (New)" << close_document << "$currentDate" << open_document                       << "lastModified" << true << close_document;        db["restaurants"].update_one(filter_builder.view(), update_builder.view());        // @end: cpp-update-top-level-fields    }    // Update an embedded document in a single document.    //找到restaurant_id是41156888的這家餐館的資訊，把地址資訊（文檔）裡面的street改成East 31st Street    {        // @begin: cpp-update-embedded-field        bsoncxx::builder::stream::document filter_builder, update_builder;        filter_builder << "restaurant_id"                       << "41156888";        update_builder << "$set" << open_document << "address.street"                       << "East 31st Street" << close_document;        db["restaurants"].update_one(filter_builder.view(), update_builder.view());        // @end: cpp-update-embedded-field    }    // Update multiple documents.    {        // @begin: cpp-update-multiple-documents        bsoncxx::builder::stream::document filter_builder, update_builder;        filter_builder << "address.zipcode"                       << "10016"                       << "cuisine"                       << "Other";        update_builder << "$set" << open_document << "cuisine"                       << "Category To Be Determined" << close_document << "$currentDate"                       << open_document << "lastModified" << true << close_document;        db["restaurants"].update_many(filter_builder.view(), update_builder.view());        // @end: cpp-update-multiple-documents    }    // Replace the contents of a single document.    {        // @begin: cpp-replace-document        //找到含有filter_builder資訊的文檔，將其中的對應資訊替換成        //replace_builder的資訊        bsoncxx::builder::stream::document filter_builder, replace_builder;        filter_builder << "restaurant_id"                       << "41704620";        replace_builder << "name"                        << "Vella 2"                        << "address" << open_document << "coord" << open_array << -73.9557413                        << 40.7720266 << close_array << "building"                        << "1480"                        << "street"                        << "2 Avenue"                        << "zipcode"                        << "10075" << close_document;        db["restaurants"].replace_one(filter_builder.view(), replace_builder.view());        // @end: cpp-replace-document    }}

2.4 remove.cpp: 刪除一個或多個collection中合格document 刪除collection中所有的document 刪除collection

int main(int, char**) {    mongocxx::instance inst{};    mongocxx::client conn{mongocxx::uri{}};    auto db = conn["test"];    // Remove all documents that match a condition.    {        // @begin: cpp-remove-matching-documents        //刪除有"borough":"Manhattan"索引值對的document        bsoncxx::builder::stream::document filter_builder;        filter_builder << "borough"                       << "Manhattan";        db["restaurants"].delete_many(filter_builder.view());        // @end: cpp-remove-matching-documents    }    // Remove one document that matches a condition.    {        // @begin: cpp-remove-justone        bsoncxx::builder::stream::document filter_builder;        filter_builder << "borough"                       << "Queens";        db["restaurants"].delete_one(filter_builder.view());        // @end: cpp-remove-justone    }    // Remove all documents in a collection.    {        // @begin: cpp-remove-all-documents        db["restaurants"].delete_many({});        // @end: cpp-remove-all-documents    }    // Drop a collection.    {        // @begin: cpp-drop-collection        db["restaurants"].drop();        // @end: cpp-drop-collection    }}

2.5 query.cpp： 查詢一個collection中所有的檔案 條件查詢含有某個索引值對的document 條件查詢含有某個索引值對（值為document，在document中繼續巢狀查詢） 條件查詢含有某個索引值對（值為array，在array中繼續巢狀查詢） 使用$gt(greater than)，$lt(less than)進行條件查詢 多個條件查詢 相當於sql裡的and 滿足多個條件中至少一個條件查詢，相當於sql中的or] 對查詢結果進行排序

int main(int, char**) {    mongocxx::instance inst{};    mongocxx::client conn{mongocxx::uri{}};    auto db = conn["test"];    // Query for all the documents in a collection.    //查詢test資料庫的restaurants集合中的所有文檔    {        // @begin: cpp-query-all        auto cursor = db["restaurants"].find({});        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-all    }    // Query for equality on a top level field.    //查詢restaurants集合中所有含"borough":"Manhattan"索引值對的文檔    {        // @begin: cpp-query-top-level-field        auto cursor = db["restaurants"].find(document{} << "borough"                                                        << "Manhattan" << finalize);        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-top-level-field    }    // Query by a field in an embedded document.    //巢狀查詢，查詢郵編為10075的餐館的文檔，address是文檔中嵌套的一個文檔，zipcode是address中的一個key，10075是zipcode對應的value.    {        // @begin: cpp-query-embedded-document        bsoncxx::builder::stream::document filter_builder;        filter_builder << "address.zipcode"                       << "10075";        auto cursor = db["restaurants"].find(filter_builder.view());        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-embedded-document    }    // Query by a field in an array.    //grades鍵對應的值是一個array，裡面有兩個文檔，在這個數組中尋找grade鍵的值是B的文檔    {        // @begin: cpp-query-field-in-array        bsoncxx::builder::stream::document filter_builder;        filter_builder << "grades.grade"                       << "B";        auto cursor = db["restaurants"].find(filter_builder.view());        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-field-in-array    }    // Query with the greater-than operator ($gt).    //在grades對應的array中尋找score大於30的文檔    {        // @begin: cpp-query-greater-than        bsoncxx::builder::stream::document filter_builder;        filter_builder << "grades.score" << open_document << "$gt" << 30 << close_document;        auto cursor = db["restaurants"].find(filter_builder.view());        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-greater-than    }    // Query with the less-than operator ($lt).    //$gt和$lt，分別是大於和小於    {        // @begin: cpp-query-less-than        bsoncxx::builder::stream::document filter_builder;        filter_builder << "grades.score" << open_document << "$lt" << 10 << close_document;        auto cursor = db["restaurants"].find(filter_builder.view());        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-less-than    }    // Query with a logical conjunction (AND) of query conditions.    //filter_builder中有多個索引值對，預設是and的關係，相當於SQL語句中的and，表示查詢cuisine是Italian並且zipcode是10075的餐館的文檔    {        // @begin: cpp-query-logical-and        bsoncxx::builder::stream::document filter_builder;        filter_builder << "cuisine"                       << "Italian"                       << "address.zipcode"                       << "10075";        auto cursor = db["restaurants"].find(filter_builder.view());        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-logical-and    }    // Query with a logical disjunction (OR) of query conditions.    //$or表示或的關係注意這個地方open_array/close_array和open_document/close_document的使用    {        // @begin: cpp-query-logical-or        bsoncxx::builder::stream::document filter_builder;        filter_builder << "$or" << open_array << open_document << "cuisine"                       << "Italian" << close_document << open_document << "address.zipcode"                       << "10075" << close_document << close_array;        auto cursor = db["restaurants"].find(filter_builder.view());        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-logical-or    }    // Sort query results.    //1和-1表示升序和降序（應該是）    {        // @begin: cpp-query-sort        mongocxx::options::find opts;        bsoncxx::builder::stream::document order_builder;        order_builder << "borough" << 1 << "address.zipcode" << -1;        opts.sort(order_builder.view());        auto cursor = db["restaurants"].find({}, opts);        for (auto&& doc : cursor) {            std::cout << bsoncxx::to_json(doc) << std::endl;        }        // @end: cpp-query-sort    }}

2.6 get_values_from_documents.cpp

從資料庫的文檔中取資料，輸出到cout

using bsoncxx::builder::stream::document;using bsoncxx::builder::stream::close_array;using bsoncxx::builder::stream::finalize;using bsoncxx::builder::stream::open_array;using bsoncxx::type;// Document model, showing array with nested documents://// {//     "_id" : ObjectId(...),//     "messagelist" : [//       {//         "uid" : 413098706,//         "status" : 2,//         "msg": "..."//       },//       ...//     ]// }// Construct a document in the format of 'messagelist'.bsoncxx::document::value new_message(int64_t uid, int32_t status, std::string msg) {    document doc;    return doc << "uid" << uid << "status" << status << "msg" << msg << finalize;}// Insert a document into the database.void insert_test_data(mongocxx::collection& coll) {    document builder{};    //這種賦值方法注意一下    builder << "messagelist" << open_array << new_message(413098706, 3, "Lorem ipsum...")            << new_message(413098707, 2, "Lorem ipsum...")            << new_message(413098708, 1, "Lorem ipsum...") << close_array;    bsoncxx::document::value doc = builder << finalize;    // Normally, one should check the return value for success.    coll.insert_one(doc.view());}// Iterate over contents of messagelist.遍曆messagelist數組中的所有內容void iterate_messagelist(const bsoncxx::document::element& ele) {    // Check validity and type before trying to iterate.    if (ele.type() == type::k_array) {        bsoncxx::array::view subarray{ele.get_array().value};        for (const bsoncxx::array::element& msg : subarray) {            // Check correct type before trying to access elements.            // Only print out fields if they exist; don't report missing fields.            if (msg.type() == type::k_document) {                bsoncxx::document::view subdoc = msg.get_document().value;                bsoncxx::document::element uid = subdoc["uid"];//使用[]訪問鍵                bsoncxx::document::element status = subdoc["status"];                bsoncxx::document::element msg = subdoc["msg"];                if (uid && uid.type() == type::k_int64) {                    std::cout << "uid: " << uid.get_int64().value << std::endl;                }                if (status && status.type() == type::k_int32) {                    std::