update

szabgab · szabgab · commit 8683b2a86122 · 2024-01-16T15:45:20.000+02:00
diff --git a/examples/surrealdb/cli-multi-counter/src/main.rs b/examples/surrealdb/cli-multi-counter/src/main.rs
@@ -34,7 +34,7 @@ async fn main() -> surrealdb::Result<()> {
         eprintln!("       {}          to list all the counters", args[0]);
         std::process::exit(1);
     }
-    
+
     if 2 == args.len() {
         let name = &args[1];
         let mut count = 0;
diff --git a/examples/surrealdb/cli-multi-counter/tests/tests.rs b/examples/surrealdb/cli-multi-counter/tests/tests.rs
@@ -34,14 +34,15 @@ fn test_counter() {
 }
 
 fn check(name: &str, expected_stdout: &str) {
-
     let result = Command::new("cargo")
         .args(["run", "-q", name])
         .output()
         .expect("command failed to start");
 
-    assert_eq!(std::str::from_utf8(&result.stdout).unwrap(), expected_stdout);
+    assert_eq!(
+        std::str::from_utf8(&result.stdout).unwrap(),
+        expected_stdout
+    );
     assert_eq!(std::str::from_utf8(&result.stderr).unwrap(), "");
     assert_eq!(result.status, ExitStatus::from_raw(0));
 }
-
diff --git a/pages/surrealdb-cli-multi-counter.md b/pages/surrealdb-cli-multi-counter.md
@@ -39,6 +39,116 @@ SurrealDB can use various storage backends, we are going to us [RocksDB](https:/
 
 ![](examples/surrealdb/cli-multi-counter/Cargo.toml)
 
+## The code
+
+### Getting the command line from args
+
+This has nothing to do with SurrealDB yet. We only create a vector from the values on the command line:
+
+
+```rust
+let args = std::env::args().collect::<Vec<String>>();
+```
+
+### Getting the path to the database
+
+We check the `DATABASE_PATH` enviroment variabl and use that if it is available. This will be used by the tests to be able to use
+a database in a temporary folder.
+
+If that variable is not available then we are going to create the database in the `db` folder in the current directory.
+
+I did not use the plain `db` because of a [bug](https://github.com/surrealdb/docs.surrealdb.com/issues/185) that was fixed recently.
+
+I also used [unwrap](/unwrap) disregarding the possibiliy that we don't have a current working directory. For a more robust solution
+you might want to deal with that as well.
+
+```rust
+let database_folder = match std::env::var("DATABASE_PATH") {
+    Ok(val) => std::path::PathBuf::from(val),
+    Err(_) => {
+        let current_dir = std::env::current_dir().unwrap();
+        current_dir.join("db")
+    }
+};
+```
+
+### Connect to the database on the filesystem
+
+Then we connect to the databse folder via the `RocksDb` driver.
+
+```rust
+let db = Surreal::new::<RocksDb>(database_folder).await?;
+```
+
+### Namespace and database
+
+Each SurrealDB installation can handle multiple namespaces and multiple databases in each namespace. We just need to pick one for each:
+
+```rust
+db.use_ns("counter_ns").use_db("counter_db").await?;
+```
+
+### Make column unique
+
+Let's make sure we don't add the same counter name twice.
+
+```rust
+let _response = db
+    .query("DEFINE INDEX counter_name ON TABLE counter COLUMNS name UNIQUE")
+    .await?;
+```
+
+### Too many arguments
+
+Tell the user how to use the tool if there is more than one value on the command line. (args includes the name of the executable file so we need to compare with 2 here).
+
+```rust
+if 2 < args.len() {
+    eprintln!("Usage: {} NAME     to count NAME", args[0]);
+    eprintln!("       {}          to list all the counters", args[0]);
+    std::process::exit(1);
+}
+```
+
+### Increment the counter
+
+I guess this is the heart of the progam where we fetch the current value of the counter using a `SELECT` statement and then
+update the value in the database. We use `INSERT` here as it can either `CREATE` a new record or `UPDATE` and existing one.
+
+```rust
+if 2 == args.len() {
+    let name = &args[1];
+    let mut count = 0;
+
+    let mut entries = db
+        .query("SELECT name, count FROM counter WHERE name = $name")
+        .bind(("name", name))
+        .await?;
+    let entries: Vec<Entry> = entries.take(0)?;
+    if let Some(entry) = entries.into_iter().next() {
+        count = entry.count;
+    }
+
+    count += 1;
+    println!("{}", count);
+
+    let response = db
+        .query("INSERT INTO counter (name, count) VALUES ($name, $count) ON DUPLICATE KEY UPDATE count=$count")
+        .bind(("name", name))
+        .bind(("count", count))
+        .await?;
+
+    match response.check() {
+        Ok(_) => return Ok(()),
+        Err(err) => {
+            eprintln!("Could not add entry {}", err);
+            std::process::exit(2);
+        }
+    };
+}
+```
+
+
 
 ## The full code
 

Original file line number	Diff line number	Diff line change
`@@ -34,7 +34,7 @@ async fn main() -> surrealdb::Result<()> {`
`34`	`34`	`eprintln!(" {} to list all the counters", args[0]);`
`35`	`35`	`std::process::exit(1);`
`36`	`36`	`}`
`37`		`-`
	`37`	`+`
`38`	`38`	`if 2 == args.len() {`
`39`	`39`	`let name = &args[1];`
`40`	`40`	`let mut count = 0;`