mirror of
https://github.com/armink/FlashDB.git
synced 2025-02-04 08:43:07 +08:00
72 lines
2.8 KiB
Markdown
72 lines
2.8 KiB
Markdown
|
# blob type KV example
|
||
|
|
|
||
|
|
This example mainly demonstrates the related functions of blob KV. Blob KV is a more commonly used type, and its value is a binary type without type restrictions. Functionally, blob KV is also compatible with string KV. In the use of API, blob KV has a set of independent APIs, which can quickly realize the storage of various types of KV to KVDB, such as basic types, arrays and structures.
|
||
|
|
|
||
|
|
## Code description
|
||
|
|
|
||
|
|
The sample code is located in `samples/kvdb_type_blob.c`, and a KV named `"temp"` is used to store the temperature value, respectively demonstrating the whole process of blob KV from `create->read->modify->delete`. The general content is as follows:
|
||
|
|
|
||
|
|
```C
|
||
|
|
void kvdb_type_blob_sample(fdb_kvdb_t kvdb)
|
||
|
|
{
|
||
|
|
struct fdb_blob blob;
|
||
|
|
|
||
|
|
FDB_INFO("==================== kvdb_type_blob_sample ====================\n");
|
||
|
|
|
||
|
|
{ /* CREATE new Key-Value */
|
||
|
|
int temp_data = 36;
|
||
|
|
|
||
|
|
/* It will create new KV node when "temp" KV not in database.
|
||
|
|
* fdb_blob_make: It's a blob make function, and it will return the blob when make finish.
|
||
|
|
*/
|
||
|
|
fdb_kv_set_blob(kvdb, "temp", fdb_blob_make(&blob, &temp_data, sizeof(temp_data)));
|
||
|
|
FDB_INFO("create the 'temp' blob KV, value is: %d\n", temp_data);
|
||
|
|
}
|
||
|
|
|
||
|
|
{ /* GET the KV value */
|
||
|
|
int temp_data = 0;
|
||
|
|
|
||
|
|
/* get the "temp" KV value */
|
||
|
|
fdb_kv_get_blob(kvdb, "temp", fdb_blob_make(&blob, &temp_data, sizeof(temp_data)));
|
||
|
|
/* the blob.saved.len is more than 0 when get the value successful */
|
||
|
|
if (blob.saved.len > 0) {
|
||
|
|
FDB_INFO("get the 'temp' value is: %d\n", temp_data);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
{ /* CHANGE the KV value */
|
||
|
|
int temp_data = 38;
|
||
|
|
|
||
|
|
/* change the "temp" KV's value to 38 */
|
||
|
|
fdb_kv_set_blob(kvdb, "temp", fdb_blob_make(&blob, &temp_data, sizeof(temp_data)));
|
||
|
|
FDB_INFO("set 'temp' value to %d\n", temp_data);
|
||
|
|
}
|
||
|
|
|
||
|
|
{ /* DELETE the KV by name */
|
||
|
|
fdb_kv_del(kvdb, "temp");
|
||
|
|
FDB_INFO("delete the 'temp' finish\n");
|
||
|
|
}
|
||
|
|
|
||
|
|
FDB_INFO("===========================================================\n");
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
## Running log
|
||
|
|
|
||
|
|
It can be seen from the log:
|
||
|
|
|
||
|
|
- First create a KV named `"temp"` and give the initial value 36℃
|
||
|
|
- Read the current value of `"temp"` KV and find that it is the same as the initial value
|
||
|
|
- Modify the value of `"temp"` KV to 38℃
|
||
|
|
- Finally delete `"temp"` KV
|
||
|
|
|
||
|
|
```
|
||
|
|
[FlashDB][sample][kvdb][blob] ==================== kvdb_type_blob_sample ====================
|
||
|
|
[FlashDB][sample][kvdb][blob] create the 'temp' blob KV, value is: 36
|
||
|
|
[FlashDB][sample][kvdb][blob] get the 'temp' value is: 36
|
||
|
|
[FlashDB][sample][kvdb][blob] set 'temp' value to 38
|
||
|
|
[FlashDB][sample][kvdb][blob] delete the 'temp' finish
|
||
|
|
[FlashDB][sample][kvdb][blob] ===========================================================
|
||
|
|
```
|
||
|
|
|