1、查询样例
bson_t query;
bson_t child;
bson_init(&query);
BSON_APPEND_INT64(&query, "id", 0);
mongoc_cursor_t m_pCursor = mongoc_collection_find(m_pCollection,
MONGOC_QUERY_NONE,
0,
0,
0,
&query,
NULL, /* Fields, NULL for all. */
NULL); /* Read Prefs, NULL for default */
bson_destroy(&query);
bson_error_t error;
if (mongoc_cursor_error(m_pCursor, &error)) {
cout << "Query Failure: " << error.message;
return;
}
const bson_t *doc;
while (!mongoc_cursor_error(m_pCursor, &error)
&& mongoc_cursor_more(m_pCursor))
{
if (mongoc_cursor_next(m_pCursor, &doc))
{
GetRecord(doc);
}
else
{
break;
}
}
if (mongoc_cursor_error(m_pCursor, &error)) {
cout << "Query Failure: " << error.message;
}
mongoc_cursor_destroy(m_pCursor);
2、获取记录
void GetRecord(const bson_t *doc)
{
bson_iter_t iter;
bson_iter_init(&iter, doc);
if (bson_iter_find(&iter, "id"))
{
cout << bson_iter_int64(&iter) << "|";
}
if (bson_iter_find(&iter, "field1"))
{
cout << bson_iter_int64(&iter) << "|";
}
if (bson_iter_find(&iter, "field2"))
{
const uint8_t *binary = NULL;
bson_subtype_t subtype = BSON_SUBTYPE_BINARY;
uint32_t binary_len = 0;
bson_iter_binary(&iter, &subtype, &binary_len, &binary);
string msg;
msg.assign((const char*)binary, binary_len);
cout << msg << endl;
}
}
3、复杂的or查询和比较查询
//id==4 or field1 <= 12
bson_t query;
bson_t child, child2, child3;
bson_init(&query);
bson_append_array_begin(&query, "$or", -1, &child);
//0: 第一个or部分
bson_append_document_begin(&child, "0", -1, &child2);
BSON_APPEND_INT64(&child2, "id", 4);
bson_append_document_end(&child, &child2);
//1:第二个or部分
bson_append_document_begin(&child, "1", -1, &child2);
//field1 <= 12
bson_append_document_begin(&child2, "field1", -1, &child3);
BSON_APPEND_INT64(&child3, "$lte", 12);
bson_append_document_end(&child2, &child3);
bson_append_document_end(&child, &child2);
bson_append_array_end(&query, &child);
char * str = bson_as_json(&query, NULL);
printf("\n%s\n", str);
posted on 2014-09-27 16:11
merlinfang 阅读(7474)
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mongodb