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// Copyright 2016 MongoDB Inc.
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <algorithm>
#include <iostream>
#include <iterator>
#include <vector>
#include <bsoncxx/array/view.hpp>
#include <bsoncxx/builder/basic/array.hpp>
#include <bsoncxx/builder/basic/document.hpp>
#include <bsoncxx/builder/basic/kvp.hpp>
#include <bsoncxx/document/value.hpp>
#include <bsoncxx/document/view.hpp>
#include <bsoncxx/json.hpp>
#include <bsoncxx/stdx/string_view.hpp>
#include <bsoncxx/string/to_string.hpp>
#include <bsoncxx/types.hpp>
#include <bsoncxx/types/bson_value/view.hpp>
using namespace bsoncxx;
int main(int, char**) {
// This example will cover the read-only BSON interface.
// Lets first build up a non-trivial BSON document using the builder interface.
using builder::basic::kvp;
using builder::basic::sub_array;
auto doc = builder::basic::document{};
kvp("team", "platforms"), kvp("id", types::b_oid{oid()}), kvp("members", [](sub_array sa) {
sa.append("tyler", "jason", "drew", "sam", "ernie", "john", "mark", "crystal");
// document::value is an owning bson document conceptually similar to string.
document::value value{doc.extract()};
// document::view is a non-owning bson document conceptually similar to string_view.
document::view view{value.view()};
// Note: array::view and array::value are the corresponding classes for arrays.
// we can print a view using to_json
std::cout << to_json(view) << std::endl;
// note that all of the interesting methods for reading BSON are defined on the view type.
// iterate over the elements in a bson document
for (document::element ele : view) {
// element is non owning view of a key-value pair within a document.
// we can use the key() method to get a string_view of the key.
stdx::string_view field_key{ele.key()};
std::cout << "Got key, key = " << field_key << std::endl;
// we can use type() to get the type of the value.
switch (ele.type()) {
case type::k_string:
std::cout << "Got String!" << std::endl;
case type::k_oid:
std::cout << "Got ObjectId!" << std::endl;
case type::k_array: {
std::cout << "Got Array!" << std::endl;
// if we have a subarray, we can access it by getting a view of it.
array::view subarr{ele.get_array().value};
for (array::element ele : subarr) {
std::cout << "array element: "
<< bsoncxx::string::to_string(ele.get_string().value) << std::endl;
std::cout << "We messed up!" << std::endl;
// usually we don't need to actually use a switch statement, because we can also
// get a variant 'value' that can hold any BSON type.
types::bson_value::view ele_val{ele.get_value()};
// If we want to search for an element we can use operator[]
// (we also provide a find() method that returns an iterator)
// Note, this does a linear search so it is O(n) in the length of the BSON document.
document::element ele{view["team"]};
if (ele) {
// this block will execute if ele was actually found
std::cout << "as expected, we have a team" << std::endl;
// Because view implements begin(), end(), we can also use standard STL algorithms.
// i.e. if we want to find the number of keys in a document we can use std::distance
using std::begin;
using std::end;
auto num_keys = std::distance(begin(view), end(view));
std::cout << "document has " << num_keys << " keys." << std::endl;
// i.e. if we want a vector of all the keys in a document, we can use std::transform
std::vector<std::string> doc_keys;
std::transform(begin(view), end(view), std::back_inserter(doc_keys), [](document::element ele) {
// note that key() returns a string_view
return bsoncxx::string::to_string(ele.key());
std::cout << "document keys are: " << std::endl;
for (auto key : doc_keys) {
std::cout << key << " " << std::endl;
std::cout << std::endl;
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