Use IntoValue and FromValue derive macros in nu_plugin_example for example usage (#13220)

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# Description
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The derive macros provided by #13031 are very useful for plugin authors.
In this PR I made use of these macros for two commands.

# User-Facing Changes
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helps us keep track of breaking changes. -->

# Tests + Formatting
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- 🟢 `toolkit fmt`
- 🟢 `toolkit clippy`
- 🟢 `toolkit test`
- 🟢 `toolkit test stdlib`

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This Example usage could be highlighted in the changelog for plugin
authors as this is probably very useful for them.

crates/nu_plugin_example/src/commands/config.rs

@@ -1,10 +1,37 @@
+use std::path::PathBuf;
+
 use nu_plugin::{EngineInterface, EvaluatedCall, SimplePluginCommand};
-use nu_protocol::{Category, LabeledError, Signature, Type, Value};
+use nu_protocol::{Category, FromValue, LabeledError, Signature, Spanned, Type, Value};
 
 use crate::ExamplePlugin;
 
 pub struct Config;
 
+/// Example config struct.
+///
+/// Using the `FromValue` derive macro, structs can be easily loaded from [`Value`]s,
+/// similar to serde's `Deserialize` macro.
+/// This is handy for plugin configs or piped data.
+/// All fields must implement [`FromValue`].
+/// For [`Option`] fields, they can be omitted in the config.
+///
+/// This example shows that nested and spanned data work too, so you can describe nested
+/// structures and get spans of values wrapped in [`Spanned`].
+/// Since this config uses only `Option`s, no field is required in the config.
+#[allow(dead_code)]
+#[derive(Debug, FromValue)]
+struct PluginConfig {
+    path: Option<Spanned<PathBuf>>,
+    nested: Option<SubConfig>,
+}
+
+#[allow(dead_code)]
+#[derive(Debug, FromValue)]
+struct SubConfig {
+    bool: bool,
+    string: String,
+}
+
 impl SimplePluginCommand for Config {
     type Plugin = ExamplePlugin;
 
@@ -39,7 +66,11 @@ impl SimplePluginCommand for Config {
     ) -> Result<Value, LabeledError> {
         let config = engine.get_plugin_config()?;
         match config {
-            Some(config) => Ok(config.clone()),
+            Some(value) => {
+                let config = PluginConfig::from_value(value.clone())?;
+                println!("got config {config:?}");
+                Ok(value)
+            }
             None => Err(LabeledError::new("No config sent").with_label(
                 "configuration for this plugin was not found in `$env.config.plugins.example`",
                 call.head,

crates/nu_plugin_example/src/commands/two.rs

@@ -1,5 +1,5 @@
 use nu_plugin::{EngineInterface, EvaluatedCall, SimplePluginCommand};
-use nu_protocol::{record, Category, LabeledError, Signature, SyntaxShape, Value};
+use nu_protocol::{Category, IntoValue, LabeledError, Signature, SyntaxShape, Value};
 
 use crate::ExamplePlugin;
 
@@ -38,14 +38,22 @@ impl SimplePluginCommand for Two {
     ) -> Result<Value, LabeledError> {
         plugin.print_values(2, call, input)?;
 
+        // Use the IntoValue derive macro and trait to easily design output data.
+        #[derive(IntoValue)]
+        struct Output {
+            one: i64,
+            two: i64,
+            three: i64,
+        }
+
         let vals = (0..10i64)
             .map(|i| {
-                let record = record! {
-                    "one" => Value::int(i, call.head),
-                    "two" => Value::int(2 * i, call.head),
-                    "three" => Value::int(3 * i, call.head),
-                };
-                Value::record(record, call.head)
+                Output {
+                    one: i,
+                    two: 2 * i,
+                    three: 3 * i,
+                }
+                .into_value(call.head)
             })
             .collect();
 

tests/plugins/config.rs

@@ -1,27 +1,5 @@
 use nu_test_support::nu_with_plugins;
 
-#[test]
-fn closure() {
-    let actual = nu_with_plugins!(
-        cwd: "tests",
-        plugin: ("nu_plugin_example"),
-        r#"
-            $env.env_value = "value from env"
-
-            $env.config = {
-                plugins: {
-                    example: {||
-                        $env.env_value
-                    }
-                }
-            }
-            example config
-        "#
-    );
-
-    assert!(actual.out.contains("value from env"));
-}
-
 #[test]
 fn none() {
     let actual = nu_with_plugins!(
@@ -34,7 +12,7 @@ fn none() {
 }
 
 #[test]
-fn record() {
+fn some() {
     let actual = nu_with_plugins!(
         cwd: "tests",
         plugin: ("nu_plugin_example"),
@@ -42,8 +20,11 @@ fn record() {
             $env.config = {
                 plugins: {
                     example: {
-                        key1: "value"
-                        key2: "other"
+                        path: "some/path",
+                        nested: {
+                            bool: true,
+                            string: "Hello Example!"
+                        }
                     }
                 }
             }
@@ -51,6 +32,6 @@ fn record() {
         "#
     );
 
-    assert!(actual.out.contains("value"));
-    assert!(actual.out.contains("other"));
+    assert!(actual.out.contains("some/path"));
+    assert!(actual.out.contains("Hello Example!"));
 }