1MONGOC_COMMON_TASK_EXAMPLES(3) libmongoc MONGOC_COMMON_TASK_EXAMPLES(3)
2
6 mongoc_common_task_examples - Common Tasks
7 Drivers for some other languages provide helper functions to perform
9 certain common tasks. In the C Driver we must explicitly build commands
10 to send to the server.
11
13 First we'll write some code to insert sample data:
14 doc-common-insert.c
16 /* Don't try to compile this file on its own. It's meant to be #included
18 by example code */
19 /* Insert some sample data */
21 bool
22 insert_data (mongoc_collection_t *collection)
23 {
24 mongoc_bulk_operation_t *bulk;
25 enum N { ndocs = 4 };
26 bson_t *docs[ndocs];
27 bson_error_t error;
28 int i = 0;
29 bool ret;
30 bulk = mongoc_collection_create_bulk_operation_with_opts (collection, NULL);
32 docs[0] = BCON_NEW ("x", BCON_DOUBLE (1.0), "tags", "[", "dog", "cat", "]");
34 docs[1] = BCON_NEW ("x", BCON_DOUBLE (2.0), "tags", "[", "cat", "]");
35 docs[2] = BCON_NEW (
36 "x", BCON_DOUBLE (2.0), "tags", "[", "mouse", "cat", "dog", "]");
37 docs[3] = BCON_NEW ("x", BCON_DOUBLE (3.0), "tags", "[", "]");
38 for (i = 0; i < ndocs; i++) {
40 mongoc_bulk_operation_insert (bulk, docs[i]);
41 bson_destroy (docs[i]);
42 docs[i] = NULL;
43 }
44 ret = mongoc_bulk_operation_execute (bulk, NULL, &error);
46 if (!ret) {
48 fprintf (stderr, "Error inserting data: %s\n", error.message);
49 }
50 mongoc_bulk_operation_destroy (bulk);
52 return ret;
53 }
54 /* A helper which we'll use a lot later on */
56 void
57 print_res (const bson_t *reply)
58 {
59 char *str;
60 BSON_ASSERT (reply);
61 str = bson_as_canonical_extended_json (reply, NULL);
62 printf ("%s\n", str);
63 bson_free (str);
64 }
65
68 This is how to use the explain command in MongoDB 3.2+:
69 explain.c
71 bool
73 explain (mongoc_collection_t *collection)
74 {
75 bson_t *command;
76 bson_t reply;
77 bson_error_t error;
78 bool res;
79 command = BCON_NEW ("explain",
81 "{",
82 "find",
83 BCON_UTF8 (COLLECTION_NAME),
84 "filter",
85 "{",
86 "x",
87 BCON_INT32 (1),
88 "}",
89 "}");
90 res = mongoc_collection_command_simple (
91 collection, command, NULL, &reply, &error);
92 if (!res) {
93 fprintf (stderr, "Error with explain: %s\n", error.message);
94 goto cleanup;
95 }
96 /* Do something with the reply */
98 print_res (&reply);
99 cleanup:
101 bson_destroy (&reply);
102 bson_destroy (command);
103 return res;
104 }
105
108 common-operations.c
109 /*
111 * Copyright 2016 MongoDB, Inc.
112 *
113 * Licensed under the Apache License, Version 2.0 (the "License");
114 * you may not use this file except in compliance with the License.
115 * You may obtain a copy of the License at
116 *
117 * http://www.apache.org/licenses/LICENSE-2.0
118 *
119 * Unless required by applicable law or agreed to in writing, software
120 * distributed under the License is distributed on an "AS IS" BASIS,
121 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
122 * See the License for the specific language governing permissions and
123 * limitations under the License.
124 */
125 #include <mongoc/mongoc.h>
128 #include <stdio.h>
129 const char *COLLECTION_NAME = "things";
132 #include "../doc-common-insert.c"
134 #include "explain.c"
135 int
138 main (int argc, char *argv[])
139 {
140 mongoc_database_t *database = NULL;
141 mongoc_client_t *client = NULL;
142 mongoc_collection_t *collection = NULL;
143 mongoc_uri_t *uri = NULL;
144 bson_error_t error;
145 char *host_and_port;
146 int res = 0;
147 if (argc < 2 || argc > 3) {
149 fprintf (stderr,
150 "usage: %s MONGOD-1-CONNECTION-STRING "
151 "[MONGOD-2-HOST-NAME:MONGOD-2-PORT]\n",
152 argv[0]);
153 fprintf (stderr,
154 "MONGOD-1-CONNECTION-STRING can be "
155 "of the following forms:\n");
156 fprintf (stderr, "localhost\t\t\t\tlocal machine\n");
157 fprintf (stderr, "localhost:27018\t\t\t\tlocal machine on port 27018\n");
158 fprintf (stderr,
159 "mongodb://user:pass@localhost:27017\t"
160 "local machine on port 27017, and authenticate with username "
161 "user and password pass\n");
162 return EXIT_FAILURE;
163 }
164 mongoc_init ();
166 if (strncmp (argv[1], "mongodb://", 10) == 0) {
168 host_and_port = bson_strdup (argv[1]);
169 } else {
170 host_and_port = bson_strdup_printf ("mongodb://%s", argv[1]);
171 }
172 uri = mongoc_uri_new_with_error (host_and_port, &error);
174 if (!uri) {
175 fprintf (stderr,
176 "failed to parse URI: %s\n"
177 "error message: %s\n",
178 host_and_port,
179 error.message);
180 res = EXIT_FAILURE;
181 goto cleanup;
182 }
183 client = mongoc_client_new_from_uri (uri);
185 if (!client) {
186 res = EXIT_FAILURE;
187 goto cleanup;
188 }
189 mongoc_client_set_error_api (client, 2);
191 database = mongoc_client_get_database (client, "test");
192 collection = mongoc_database_get_collection (database, COLLECTION_NAME);
193 printf ("Inserting data\n");
195 if (!insert_data (collection)) {
196 res = EXIT_FAILURE;
197 goto cleanup;
198 }
199 printf ("explain\n");
201 if (!explain (collection)) {
202 res = EXIT_FAILURE;
203 goto cleanup;
204 }
205 cleanup:
207 if (collection) {
208 mongoc_collection_destroy (collection);
209 }
210 if (database) {
212 mongoc_database_destroy (database);
213 }
214 if (client) {
216 mongoc_client_destroy (client);
217 }
218 if (uri) {
220 mongoc_uri_destroy (uri);
221 }
222 bson_free (host_and_port);
224 mongoc_cleanup ();
225 return res;
226 }
227 First launch two separate instances of mongod (must be done from sepa‐
230 rate shells):
231 $ mongod
233 $ mkdir /tmp/db2
235 $ mongod --dbpath /tmp/db2 --port 27018 # second instance
236 Now compile and run the example program:
238 $ cd examples/common_operations/$ gcc -Wall -o example common-operations.c $(pkg-config --cflags --libs libmongoc-1.0)$ ./example localhost:27017 localhost:27018
240 Inserting data
241 explain
242 {
243 "executionStats" : {
244 "allPlansExecution" : [],
245 "executionStages" : {
246 "advanced" : 19,
247 "direction" : "forward" ,
248 "docsExamined" : 76,
249 "executionTimeMillisEstimate" : 0,
250 "filter" : {
251 "x" : {
252 "$eq" : 1
253 }
254 },
255 "invalidates" : 0,
256 "isEOF" : 1,
257 "nReturned" : 19,
258 "needTime" : 58,
259 "needYield" : 0,
260 "restoreState" : 0,
261 "saveState" : 0,
262 "stage" : "COLLSCAN" ,
263 "works" : 78
264 },
265 "executionSuccess" : true,
266 "executionTimeMillis" : 0,
267 "nReturned" : 19,
268 "totalDocsExamined" : 76,
269 "totalKeysExamined" : 0
270 },
271 "ok" : 1,
272 "queryPlanner" : {
273 "indexFilterSet" : false,
274 "namespace" : "test.things",
275 "parsedQuery" : {
276 "x" : {
277 "$eq" : 1
278 }
279 },
280 "plannerVersion" : 1,
281 "rejectedPlans" : [],
282 "winningPlan" : {
283 "direction" : "forward" ,
284 "filter" : {
285 "x" : {
286 "$eq" : 1
287 }
288 },
289 "stage" : "COLLSCAN"
290 }
291 },
292 "serverInfo" : {
293 "gitVersion" : "05552b562c7a0b3143a729aaa0838e558dc49b25" ,
294 "host" : "MacBook-Pro-57.local",
295 "port" : 27017,
296 "version" : "3.2.6"
297 }
298 }
299
301 MongoDB, Inc
302
304 2017-present, MongoDB, Inc
3051.20.0 Nov 18, 2021 MONGOC_COMMON_TASK_EXAMPLES(3)