1MONGOC_COLLECTION_FIND_WITH_OPTS(3)libmongocMONGOC_COLLECTION_FIND_WITH_OPTS(3)
2
6 mongoc_collection_find_with_opts - mongoc_collection_find_with_opts()
7
9 mongoc_cursor_t *
10 mongoc_collection_find_with_opts (mongoc_collection_t *collection,
11 const bson_t *filter,
12 const bson_t *opts,
13 const mongoc_read_prefs_t *read_prefs)
14 BSON_GNUC_WARN_UNUSED_RESULT;
15
17 • collection: A mongoc_collection_t.
18 • filter: A bson_t containing the query to execute.
20 • opts: A bson_t query options, including sort order and which fields
22 to return. Can be NULL.
23 • read_prefs: A mongoc_read_prefs_t or NULL.
25
27 Query on collection, passing arbitrary query options to the server in
28 opts.
29 To target a specific server, include an integer "serverId" field in
31 opts with an id obtained first by calling
32 mongoc_client_select_server(), then mongoc_server_description_id() on
33 its return value.
34 Read preferences, read concern, and collation can be overridden by var‐
36 ious sources. In a transaction, read concern and write concern are pro‐
37 hibited in opts and the read preference must be primary or NULL. The
38 highest-priority sources for these options are listed first in the fol‐
39 lowing table. No write concern is applied.
40 ┌─────────────────┬──────────────┬───────────┐
42 │Read Preferences │ Read Concern │ Collation │
43 ├─────────────────┼──────────────┼───────────┤
44 │read_prefs │ opts │ opts │
45 ├─────────────────┼──────────────┼───────────┤
46 │Transaction │ Transaction │ │
47 ├─────────────────┼──────────────┼───────────┤
48 │collection │ │ │
49 └─────────────────┴──────────────┴───────────┘
50 See the example for transactions and for the "distinct" command with
52 opts.
53 This function is considered a retryable read operation. Upon a tran‐
55 sient error (a network error, errors due to replica set failover, etc.)
56 the operation is safely retried once. If retryreads is false in the
57 URI (see mongoc_uri_t) the retry behavior does not apply.
58
60 This function returns a newly allocated mongoc_cursor_t that should be
61 freed with mongoc_cursor_destroy() when no longer in use. The returned
62 mongoc_cursor_t is never NULL, even on error. The user must call
63 mongoc_cursor_next() on the returned mongoc_cursor_t to execute the
64 initial command.
65 Cursor errors can be checked with mongoc_cursor_error_document(). It
67 always fills out the bson_error_t if an error occurred, and optionally
68 includes a server reply document if the error occurred server-side.
69 WARNING:
71 Failure to handle the result of this function is a programming er‐
72 ror.
73
75 Print First Ten Documents in a Collection
76 #include <bson/bson.h>
78 #include <mongoc/mongoc.h>
79 #include <stdio.h>
80 static void
82 print_ten_documents (mongoc_collection_t *collection)
83 {
84 bson_t *filter;
85 bson_t *opts;
86 mongoc_cursor_t *cursor;
87 bson_error_t error;
88 const bson_t *doc;
89 char *str;
90 /* filter by "foo": 1, order by "bar" descending */
92 filter = BCON_NEW ("foo", BCON_INT32 (1));
93 opts = BCON_NEW (
94 "limit", BCON_INT64 (10), "sort", "{", "bar", BCON_INT32 (-1), "}");
95 cursor = mongoc_collection_find_with_opts (collection, filter, opts, NULL);
97 while (mongoc_cursor_next (cursor, &doc)) {
99 str = bson_as_canonical_extended_json (doc, NULL);
100 printf ("%s\n", str);
101 bson_free (str);
102 }
103 if (mongoc_cursor_error (cursor, &error)) {
105 fprintf (stderr, "An error occurred: %s\n", error.message);
106 }
107 mongoc_cursor_destroy (cursor);
109 bson_destroy (filter);
110 bson_destroy (opts);
111 }
112 More examples of modifying the query with opts:
114 bson_t *filter;
116 bson_t *opts;
117 mongoc_read_prefs_t *read_prefs;
118 filter = BCON_NEW ("foo", BCON_INT32 (1));
120 /* Include "field_name_one" and "field_name_two" in "projection", omit
122 * others. "_id" must be specifically removed or it is included by default.
123 */
124 opts = BCON_NEW ("projection", "{",
125 "field_name_one", BCON_BOOL (true),
126 "field_name_two", BCON_BOOL (true),
127 "_id", BCON_BOOL (false),
128 "}",
129 "tailable", BCON_BOOL (true),
130 "awaitData", BCON_BOOL (true),
131 "sort", "{", "bar", BCON_INT32 (-1), "}",
132 "collation", "{",
133 "locale", BCON_UTF8("en_US"),
134 "caseFirst", BCON_UTF8 ("lower"),
135 "}");
136 read_prefs = mongoc_read_prefs_new (MONGOC_READ_SECONDARY);
138 cursor =
140 mongoc_collection_find_with_opts (collection, filter, opts, read_prefs);
141 The following options are supported.
143 ┌────────────────┬──────────────────┬─────────────────┬──────────────┐
145 │Option │ BSON type │ Option │ BSON type │
146 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
147 │projection │ document │ max │ document │
148 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
149 │sort │ document │ maxTimeMS │ non-negative │
150 │ │ │ │ int64 │
151 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
152 │skip │ non-negative │ maxAwaitTimeMS │ non-negative │
153 │ │ int64 │ │ int64 │
154 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
155 │limit │ non-negative │ min │ document │
156 │ │ int64 │ │ │
157 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
158 │batchSize │ non-negative │ noCursorTimeout │ bool │
159 │ │ int64 │ │ │
160 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
161 │exhaust │ bool │ oplogReplay │ bool │
162 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
163 │hint │ string or docu‐ │ readConcern │ document │
164 │ │ ment │ │ │
165 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
166 │allowPartialRe‐ │ bool │ returnKey │ bool │
167 │sults │ │ │ │
168 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
169 │awaitData │ bool │ sessionId │ (none) │
170 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
171 │collation │ document │ showRecordId │ bool │
172 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
173 │comment │ any │ singleBatch │ bool │
174 ├────────────────┼──────────────────┼─────────────────┼──────────────┤
175 │allowDiskUse │ bool │ let │ document │
176 └────────────────┴──────────────────┴─────────────────┴──────────────┘
177 All options are documented in the reference page for the "find" command
179 in the MongoDB server manual, except for "maxAwaitTimeMS", "sessionId",
180 and "exhaust".
181 "maxAwaitTimeMS" is the maximum amount of time for the server to wait
183 on new documents to satisfy a query, if "tailable" and "awaitData" are
184 both true. If no new documents are found, the tailable cursor receives
185 an empty batch. The "maxAwaitTimeMS" option is ignored for MongoDB
186 older than 3.4.
187 To add a "sessionId", construct a mongoc_client_session_t with
189 mongoc_client_start_session(). You can begin a transaction with
190 mongoc_client_session_start_transaction(), optionally with a
191 mongoc_transaction_opt_t that overrides the options inherited from col‐
192 lection. Then use mongoc_client_session_append() to add the session to
193 opts. See the example code for mongoc_client_session_t.
194 To add a "readConcern", construct a mongoc_read_concern_t with
196 mongoc_read_concern_new() and configure it with
197 mongoc_read_concern_set_level(). Then use mongoc_read_concern_append()
198 to add the read concern to opts.
199 "exhaust" requests the construction of an exhaust cursor. For MongoDB
201 servers before 5.1, this option converts the command into a legacy
202 OP_QUERY message. For MongoDB servers 5.1 and newer, this option is ig‐
203 nored and a normal cursor is constructed instead.
204 For some options like "collation", the driver returns an error if the
206 server version is too old to support the feature. Any fields in opts
207 that are not listed here are passed to the server unmodified.
208 allowDiskUse is only supported in MongoDB 4.4+.
210 comment only supports string values prior to MongoDB 4.4.
212
214 The snapshot boolean option is removed in MongoDB 4.0. The maxScan op‐
215 tion, a non-negative int64, is deprecated in MongoDB 4.0 and will be
216 removed in a future MongoDB version. The oplogReplay boolean option is
217 deprecated in MongoDB 4.4. All of these options are supported by the C
218 Driver with older MongoDB versions.
219 SEE ALSO:
221 The "find" command in the MongoDB Manual. All options listed there are supported by the C Driver. For MongoDB servers before 3.2, the driver transparently converts the query to a legacy OP_QUERY message.
222
225 With MongoDB before 3.2, a query with option $explain: true returns in‐
226 formation about the query plan, instead of the query results. Beginning
227 in MongoDB 3.2, there is a separate "explain" command. The driver will
228 not convert "$explain" queries to "explain" commands, you must call the
229 "explain" command explicitly:
230 /* MongoDB 3.2+, "explain" command syntax */
232 command = BCON_NEW ("explain", "{",
233 "find", BCON_UTF8 ("collection_name"),
234 "filter", "{", "foo", BCON_INT32 (1), "}",
235 "}");
236 mongoc_collection_command_simple (collection, command, NULL, &reply, &error);
238 SEE ALSO:
240 The "explain" command in the MongoDB Manual.
241
244 MongoDB, Inc
245
247 2017-present, MongoDB, Inc
2481.24.3 Aug 17, 202M3ONGOC_COLLECTION_FIND_WITH_OPTS(3)