Using the Key-Value DB
The key-value storage in W3bstream is specifically designed for storing data that can be retrieved using a unique key. This functionality proves useful for various purposes, such as storing application settings and maintaining status information.
To store an object called "
myObj" in the key-value database, a W3bstream applet can utilize the SetDB function. The example below demonstrates how you can store and retrieve an integer value from the key-value storage:
AssemblyScript
Rust
Go
import { GetDB, SetDB } from "@w3bstream/wasm-sdk";
export { alloc } from "@w3bstream/wasm-sdk";
export function my_habdler(rid: i32): i32 {
// Read the data stored under the key "users_count"
let value = GetDB("users_count");
// Convert the string to i32
let users_count = value ? parseInt(value) : 0;
// store the new value
let result = SetDB("users_count", (i32(users_count) + 1));
return 0;
}
use ws_sdk::database::kv::{get, set};
use ws_sdk::log::log_info;
#[no_mangle]
pub extern "C" fn my_handler(_rid: i32) -> i32 {
// Read the data stored under the key "users_count"
let value = get("users_count").unwrap_or("0".into());
// Convert the bytes vector to string and parse it to i32
let int_value = String::from_utf8(value).unwrap().parse::<i32>().unwrap();
// Log the value
log_info(&format!("Current users count: {}", int_value));
// Increment and store the incremented the value as string bytes
let result = set("users_count", (int_value + 1).to_string().into_bytes());
0
}
// Add a main() if required by the compiler
fn main() { }
package main
import (
"fmt"
"github.com/machinefi/w3bstream-wasm-golang-sdk/database"
"github.com/machinefi/w3bstream-wasm-golang-sdk/log"
)
func my_handle(rid int32) int32 {
value, _ := database.Get("users_count")
usersCount, _ := strconv.Atoi(string(value))
w3bstream.Set("users_count", []byte(strconv.Itoa(usersCount+1)))
return 0
}
func main() {}