Generate rust type from json

Cargo.lock

@@ -710,6 +710,7 @@ dependencies = [
  "ide-db",
  "itertools",
  "profile",
+ "serde_json",
  "sourcegen",
  "stdx",
  "syntax",

crates/ide-diagnostics/Cargo.toml

@@ -15,6 +15,7 @@ itertools = "0.10.3"
 
 
 either = "1.7.0"
+serde_json = "1.0.82"
 
 profile = { path = "../profile", version = "0.0.0" }
 stdx = { path = "../stdx", version = "0.0.0" }

crates/ide-diagnostics/src/handlers/json_is_not_rust.rs

@@ -0,0 +1,201 @@
+//! This diagnostic provides an assist for creating a struct definition from a JSON
+//! example.
+
+use ide_db::{base_db::FileId, source_change::SourceChange};
+use itertools::Itertools;
+use stdx::format_to;
+use syntax::{
+    ast::{self, make},
+    SyntaxKind, SyntaxNode,
+};
+use text_edit::TextEdit;
+
+use crate::{fix, Diagnostic, Severity};
+
+#[derive(Default)]
+struct State {
+    result: String,
+    struct_counts: usize,
+}
+
+impl State {
+    fn generate_new_name(&mut self) -> ast::Name {
+        self.struct_counts += 1;
+        make::name(&format!("Struct{}", self.struct_counts))
+    }
+
+    fn build_struct(&mut self, value: &serde_json::Map<String, serde_json::Value>) -> ast::Type {
+        let name = self.generate_new_name();
+        let ty = make::ty(&name.to_string());
+        let strukt = make::struct_(
+            None,
+            name,
+            None,
+            make::record_field_list(value.iter().sorted_unstable_by_key(|x| x.0).map(
+                |(name, value)| make::record_field(None, make::name(name), self.type_of(value)),
+            ))
+            .into(),
+        );
+        format_to!(self.result, "#[derive(Serialize, Deserialize)]\n{}\n", strukt);
+        ty
+    }
+
+    fn type_of(&mut self, value: &serde_json::Value) -> ast::Type {
+        match value {
+            serde_json::Value::Null => make::ty_unit(),
+            serde_json::Value::Bool(_) => make::ty("bool"),
+            serde_json::Value::Number(x) => make::ty(if x.is_i64() { "i64" } else { "f64" }),
+            serde_json::Value::String(_) => make::ty("String"),
+            serde_json::Value::Array(x) => {
+                let ty = match x.iter().next() {
+                    Some(x) => self.type_of(x),
+                    None => make::ty_placeholder(),
+                };
+                make::ty(&format!("Vec<{ty}>"))
+            }
+            serde_json::Value::Object(x) => self.build_struct(x),
+        }
+    }
+}
+
+pub(crate) fn json_in_items(acc: &mut Vec<Diagnostic>, file_id: FileId, node: &SyntaxNode) {
+    if node.kind() == SyntaxKind::ERROR
+        && node.first_token().map(|x| x.kind()) == Some(SyntaxKind::L_CURLY)
+        && node.last_token().map(|x| x.kind()) == Some(SyntaxKind::R_CURLY)
+    {
+        let node_string = node.to_string();
+        if let Ok(x) = serde_json::from_str(&node_string) {
+            if let serde_json::Value::Object(x) = x {
+                let range = node.text_range();
+                let mut edit = TextEdit::builder();
+                edit.delete(range);
+                let mut state = State::default();
+                state.build_struct(&x);
+                edit.insert(range.start(), state.result);
+                acc.push(
+                    Diagnostic::new(
+                        "json-is-not-rust",
+                        "JSON syntax is not valid as a Rust item",
+                        range,
+                    )
+                    .severity(Severity::WeakWarning)
+                    .with_fixes(Some(vec![fix(
+                        "convert_json_to_struct",
+                        "Convert JSON to struct",
+                        SourceChange::from_text_edit(file_id, edit.finish()),
+                        range,
+                    )])),
+                );
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        tests::{check_diagnostics_with_config, check_fix, check_no_fix},
+        DiagnosticsConfig,
+    };
+
+    #[test]
+    fn diagnostic_for_simple_case() {
+        let mut config = DiagnosticsConfig::default();
+        config.disabled.insert("syntax-error".to_string());
+        check_diagnostics_with_config(
+            config,
+            r#"
+            { "foo": "bar" }
+         // ^^^^^^^^^^^^^^^^ 💡 weak: JSON syntax is not valid as a Rust item
+"#,
+        );
+    }
+
+    #[test]
+    fn types_of_primitives() {
+        check_fix(
+            r#"
+            {$0
+                "foo": "bar",
+                "bar": 2.3,
+                "baz": null,
+                "bay": 57,
+                "box": true
+            }
+            "#,
+            r#"
+            #[derive(Serialize, Deserialize)]
+            struct Struct1{ bar: f64, bay: i64, baz: (), r#box: bool, foo: String }
+
+            "#,
+        );
+    }
+
+    #[test]
+    fn nested_structs() {
+        check_fix(
+            r#"
+            {$0
+                "foo": "bar",
+                "bar": {
+                    "kind": "Object",
+                    "value": {}
+                }
+            }
+            "#,
+            r#"
+            #[derive(Serialize, Deserialize)]
+            struct Struct3{  }
+            #[derive(Serialize, Deserialize)]
+            struct Struct2{ kind: String, value: Struct3 }
+            #[derive(Serialize, Deserialize)]
+            struct Struct1{ bar: Struct2, foo: String }
+
+            "#,
+        );
+    }
+
+    #[test]
+    fn arrays() {
+        check_fix(
+            r#"
+            {
+                "of_string": ["foo", "2", "x"], $0
+                "of_object": [{
+                    "x": 10,
+                    "y": 20
+                }, {
+                    "x": 10,
+                    "y": 20
+                }],
+                "nested": [[[2]]],
+                "empty": []
+            }
+            "#,
+            r#"
+            #[derive(Serialize, Deserialize)]
+            struct Struct2{ x: i64, y: i64 }
+            #[derive(Serialize, Deserialize)]
+            struct Struct1{ empty: Vec<_>, nested: Vec<Vec<Vec<i64>>>, of_object: Vec<Struct2>, of_string: Vec<String> }
+
+            "#,
+        );
+    }
+
+    #[test]
+    fn no_emit_outside_of_item_position() {
+        check_no_fix(
+            r#"
+            fn foo() {
+                let json = {$0
+                    "foo": "bar",
+                    "bar": {
+                        "kind": "Object",
+                        "value": {}
+                    }
+                };
+            }
+            "#,
+        );
+    }
+}

crates/ide-diagnostics/src/lib.rs

@@ -50,6 +50,7 @@ mod handlers {
     pub(crate) mod field_shorthand;
     pub(crate) mod useless_braces;
     pub(crate) mod unlinked_file;
+    pub(crate) mod json_is_not_rust;
 }
 
 #[cfg(test)]
@@ -175,6 +176,7 @@ pub fn diagnostics(
     for node in parse.tree().syntax().descendants() {
         handlers::useless_braces::useless_braces(&mut res, file_id, &node);
         handlers::field_shorthand::field_shorthand(&mut res, file_id, &node);
+        handlers::json_is_not_rust::json_in_items(&mut res, file_id, &node);
     }
 
     let module = sema.to_module_def(file_id);