DOCSP-61800: CPP Getting Started

README.md

@@ -7,7 +7,7 @@ includes its own setup instructions.
 ## Available Client Libraries
 
 - C
-- C++
+- [C++](cpp/hello-world/README.md)
 - EF
 - [Go](go/hello-world/README.md)
 - Hibernate

cpp/hello-world/.gitignore

@@ -0,0 +1 @@
+build/

cpp/hello-world/CMakeLists.txt

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+cmake_minimum_required(VERSION 3.15)
+
+project(hello-world CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+find_package(mongocxx 4.0 REQUIRED)
+
+add_executable(hello-world main.cpp)
+
+target_link_libraries(hello-world PRIVATE mongo::mongocxx_shared)

cpp/hello-world/README.md

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+# Get Started with the MongoDB C++ Driver
+
+This sample application connects to a MongoDB deployment, seeds a small
+set of sample product documents, and retrieves one of them. Because the
+app inserts its own data, you don't need to load an external dataset.
+
+## Prerequisites
+
+Before you begin, complete the [Atlas Get Started guide](https://www.mongodb.com/docs/get-started/)
+to create a free Atlas deployment and save your database user
+credentials.
+
+You also need the following components installed in your development environment:
+
+- A C++17-compatible compiler
+- CMake 3.15 or later
+- The MongoDB C++ driver (mongocxx) 4.0 or later
+
+## Installation
+
+Clone this repository:
+
+```bash
+git clone https://github.com/mongodb/mongodb-code-examples
+```
+
+Install the MongoDB C++ driver (mongocxx). Follow the
+[C++ driver installation guide](https://www.mongodb.com/docs/languages/cpp/cpp-driver/current/installation/)
+for your platform.
+
+Navigate into the `cpp/hello-world` project directory and build the
+application with CMake:
+
+```bash
+cd mongodb-code-examples/cpp/hello-world
+cmake -S . -B build
+cmake --build build
+```
+
+## Connect to MongoDB
+
+Set your connection string as an environment variable, replacing
+`<connection string uri>` with your connection string:
+
+```bash
+export MONGODB_URI="<connection string uri>"
+```
+
+## Run the Application
+
+```bash
+./build/hello-world
+```
+
+When you run the app, it inserts a few product documents into the
+`get_started.products` collection, then queries and prints one of them:
+
+```
+{ "_id" : { "$oid" : "..." }, "name" : "Wireless Mouse", "category" : "Electronics", "price" : 24.99, "tags" : [ "wireless", "usb", "ergonomic" ] }
+```
+
+You can run the app more than once. It clears the collection before
+each run, so the results stay consistent.
+
+If you encounter an error or see no output, verify that you set the
+`MONGODB_URI` environment variable correctly.

cpp/hello-world/main.cpp

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+#include <array>
+#include <charconv>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+
+#include <bsoncxx/builder/basic/array.hpp>
+#include <bsoncxx/builder/basic/document.hpp>
+#include <mongocxx/client.hpp>
+#include <mongocxx/instance.hpp>
+#include <mongocxx/uri.hpp>
+
+using bsoncxx::builder::basic::kvp;
+using bsoncxx::builder::basic::make_array;
+using bsoncxx::builder::basic::make_document;
+
+// A few sample product documents seeded by this app so you can run it
+// without loading an external dataset.
+std::vector<bsoncxx::document::value> sample_products() {
+    std::vector<bsoncxx::document::value> products;
+
+    products.push_back(make_document(
+        kvp("name", "Wireless Mouse"),
+        kvp("category", "Electronics"),
+        kvp("price", 24.99),
+        kvp("tags", make_array("wireless", "usb", "ergonomic"))));
+
+    products.push_back(make_document(
+        kvp("name", "Standing Desk"),
+        kvp("category", "Furniture"),
+        kvp("price", 349.99),
+        kvp("tags", make_array("adjustable", "office"))));
+
+    products.push_back(make_document(
+        kvp("name", "Noise-Cancelling Headphones"),
+        kvp("category", "Electronics"),
+        kvp("price", 199.99),
+        kvp("tags", make_array("bluetooth", "wireless", "over-ear"))));
+
+    return products;
+}
+
+int main() {
+    const char* uri_env = std::getenv("MONGODB_URI");
+    if (uri_env == nullptr) {
+        std::cerr << "Set the MONGODB_URI environment variable to your "
+                     "connection string.\n";
+        return EXIT_FAILURE;
+    }
+
+    mongocxx::instance instance{};
+    mongocxx::client client{mongocxx::uri{uri_env}};
+
+    auto database = client["get_started"];
+    auto products = database["products"];
+
+    // Seed the collection so the app has data to query. Clearing the
+    // collection first keeps results consistent across repeated runs.
+    products.delete_many({});
+    products.insert_many(sample_products());
+
+    auto filter = make_document(kvp("name", "Wireless Mouse"));
+    auto product = products.find_one(filter.view());
+    if (product) {
+        auto view = product->view();
+
+        std::array<char, 32> buf;
+        auto [ptr, ec] = std::to_chars(
+            buf.data(), buf.data() + buf.size(), view["price"].get_double().value);
+        std::string price(buf.data(), ptr);
+
+        std::cout << "{ \"_id\" : { \"$oid\" : \""
+                  << view["_id"].get_oid().value.to_string() << "\" }"
+                  << ", \"name\" : \"" << view["name"].get_string().value << "\""
+                  << ", \"category\" : \"" << view["category"].get_string().value
+                  << "\""
+                  << ", \"price\" : " << price << ", \"tags\" : [";
+        bool first = true;
+        for (auto tag : view["tags"].get_array().value) {
+            std::cout << (first ? " " : ", ") << "\"" << tag.get_string().value
+                      << "\"";
+            first = false;
+        }
+        std::cout << " ] }\n";
+    }
+
+    return EXIT_SUCCESS;
+}