[feat] Adding support for pydantic v1 (#1968)

<!-- ELLIPSIS_HIDDEN -->


> [!IMPORTANT]
> Adds support for Pydantic v1 by introducing a new generator output
type and updating templates and logic to handle both Pydantic versions.
> 
>   - **Behavior**:
> - Adds support for Pydantic v1 by introducing
`GeneratorOutputType::PythonPydanticV1`.
> - Updates `generate()` in `python/mod.rs` to accept `legacy_pydantic`
flag.
> - Modifies `parse_py_type()` in `parse_py_type.rs` to check Pydantic
version and adjust field extraction logic.
>   - **Templates**:
> - Updates `partial_types.py.j2` and `types.py.j2` to conditionally use
`ConfigDict` or `Config` based on Pydantic version.
>     - Adjusts class definitions to use `GenericModel` for Pydantic v1.
>   - **Misc**:
> - Changes `client_type` from `Option<GeneratorOutputType>` to
`GeneratorOutputType` in `GeneratorArgs`.
> - Updates `generators.baml` to include a new generator for Pydantic
v1.
> - Adds integration tests for Pydantic v1 in
`python-v1/tests/test_typebuilder.py`.
> 
> <sup>This description was created by </sup>[<img alt="Ellipsis"
src="https://img.shields.io/badge/Ellipsis-blue?color=175173">](https://www.ellipsis.dev?ref=BoundaryML%2Fbaml&utm_source=github&utm_medium=referral)<sup>
for ec7cd42. You can
[customize](https://app.ellipsis.dev/BoundaryML/settings/summaries) this
summary. It will automatically update as commits are pushed.</sup>


<!-- ELLIPSIS_HIDDEN -->

Author: hellovai

engine/baml-lib/baml-types/src/generator.rs

@@ -17,6 +17,9 @@ pub enum GeneratorOutputType {
     #[strum(serialize = "python/pydantic")]
     PythonPydantic,
 
+    #[strum(serialize = "python/pydantic/v1")]
+    PythonPydanticV1,
+
     #[strum(serialize = "typescript")]
     Typescript,
 
@@ -43,6 +46,9 @@ impl GeneratorOutputType {
             // Due to legacy reasons, PythonPydantic and Typescript default to async
             // DO NOT CHANGE THIS DEFAULT EVER OR YOU WILL BREAK EXISTING USERS
             Self::PythonPydantic => GeneratorDefaultClientMode::Async,
+            // mimic legacy version
+            Self::PythonPydanticV1 => GeneratorDefaultClientMode::Async,
+
             Self::Typescript => GeneratorDefaultClientMode::Async,
             Self::TypescriptReact => GeneratorDefaultClientMode::Async,
             Self::RubySorbet => GeneratorDefaultClientMode::Sync,
@@ -55,6 +61,7 @@ impl GeneratorOutputType {
         match self {
             Self::OpenApi => GeneratorDefaultClientMode::Sync,
             Self::PythonPydantic => GeneratorDefaultClientMode::Sync,
+            Self::PythonPydanticV1 => GeneratorDefaultClientMode::Sync,
             Self::Typescript => GeneratorDefaultClientMode::Async,
             Self::TypescriptReact => GeneratorDefaultClientMode::Async,
             Self::RubySorbet => GeneratorDefaultClientMode::Sync,

engine/baml-runtime/src/cli/generate.rs

@@ -50,7 +50,7 @@ impl GenerateArgs {
                     // this has no meaning
                     GeneratorDefaultClientMode::Sync
                 }
-                internal_baml_core::configuration::GeneratorOutputType::PythonPydantic => {
+                internal_baml_core::configuration::GeneratorOutputType::PythonPydantic | internal_baml_core::configuration::GeneratorOutputType::PythonPydanticV1 => {
                     // TODO: Consider changing this default to sync
                     GeneratorDefaultClientMode::Async
                 }
@@ -82,7 +82,7 @@ impl GenerateArgs {
                         false,
                         default_client_mode,
                         vec![],
-                        None,
+                        client_type,
                         if matches!(
                             client_type,
                             internal_baml_core::configuration::GeneratorOutputType::Go

engine/baml-runtime/src/cli/init.rs

@@ -84,7 +84,7 @@ impl InitArgs {
             "Created new BAML project in {} for {}",
             baml_src.display(),
             match output_type {
-                GeneratorOutputType::PythonPydantic => "Python clients".to_string(),
+                GeneratorOutputType::PythonPydanticV1 | GeneratorOutputType::PythonPydantic => "Python clients".to_string(),
                 GeneratorOutputType::Typescript => "TypeScript clients".to_string(),
                 GeneratorOutputType::RubySorbet => "Ruby clients".to_string(),
                 GeneratorOutputType::OpenApi => match &self.openapi_client_type {
@@ -98,7 +98,7 @@ impl InitArgs {
         baml_log::info!(
             "Follow instructions at https://docs.boundaryml.com/docs/get-started/quickstart/{}",
             match output_type {
-                GeneratorOutputType::PythonPydantic => "python",
+                GeneratorOutputType::PythonPydanticV1 | GeneratorOutputType::PythonPydantic => "python",
                 GeneratorOutputType::Typescript => "typescript",
                 GeneratorOutputType::RubySorbet => "ruby",
                 GeneratorOutputType::OpenApi => "openapi",
@@ -121,6 +121,7 @@ fn generate_main_baml_content(
         | GeneratorOutputType::RubySorbet
         | GeneratorOutputType::Go => "".to_string(),
         GeneratorOutputType::PythonPydantic
+        | GeneratorOutputType::PythonPydanticV1
         | GeneratorOutputType::Typescript
         | GeneratorOutputType::TypescriptReact => format!(
             r#"

engine/baml-runtime/src/cli/serve/mod.rs

@@ -571,7 +571,7 @@ Tip: test that the server is up using `curl http://localhost:{}/_debug/ping`
             true,
             GeneratorDefaultClientMode::Sync,
             Vec::new(),
-            None,
+            GeneratorOutputType::OpenApi,
             None,
             None,
         )

engine/baml-runtime/src/lib.rs

@@ -924,7 +924,7 @@ impl BamlRuntime {
                         no_version_check,
                         generator.default_client_mode(),
                         generator.on_generate.clone(),
-                        Some(generator.output_type),
+                        generator.output_type,
                         generator.client_package_name.clone(),
                         generator.module_format,
                     )?,

engine/language_client_codegen/src/go/mod.rs

@@ -278,7 +278,7 @@ class Foo {
             true,
             GeneratorDefaultClientMode::Async,
             Vec::new(),
-            Some(GeneratorOutputType::Go),
+            GeneratorOutputType::Go,
             Some("example.com/integ-tests".to_string()),
             None,
         )

engine/language_client_codegen/src/lib.rs

@@ -38,7 +38,7 @@ pub struct GeneratorArgs {
     on_generate: Vec<String>,
 
     // The type of client to generate
-    client_type: Option<GeneratorOutputType>,
+    client_type: GeneratorOutputType,
     client_package_name: Option<String>,
 
     // For TS generators, we can choose between CJS and ESM module formats
@@ -64,7 +64,7 @@ impl GeneratorArgs {
         no_version_check: bool,
         default_client_mode: GeneratorDefaultClientMode,
         on_generate: Vec<String>,
-        client_type: Option<GeneratorOutputType>,
+        client_type: GeneratorOutputType,
         client_package_name: Option<String>,
         module_format: Option<ModuleFormat>,
     ) -> Result<Self> {
@@ -207,7 +207,8 @@ impl GenerateClient for GeneratorOutputType {
         // Generate files
         let files = match self {
             GeneratorOutputType::OpenApi => openapi::generate(ir, gen),
-            GeneratorOutputType::PythonPydantic => python::generate(ir, gen),
+            GeneratorOutputType::PythonPydantic => python::generate(ir, gen, false),
+            GeneratorOutputType::PythonPydanticV1 => python::generate(ir, gen, true),
             GeneratorOutputType::RubySorbet => ruby::generate(ir, gen),
             GeneratorOutputType::Typescript => typescript::generate(ir, gen),
             GeneratorOutputType::TypescriptReact => typescript::generate(ir, gen),

engine/language_client_codegen/src/python/generate_types.rs

@@ -16,6 +16,7 @@ use internal_baml_core::ir::{
 pub(crate) struct PythonTypes<'ir> {
     enums: Vec<PythonEnum<'ir>>,
     classes: Vec<PythonClass<'ir>>,
+    is_pydantic_2: bool,
     structural_recursive_alias_cycles: Vec<PythonTypeAlias<'ir>>,
 }
 
@@ -51,6 +52,7 @@ struct PythonTypeAlias<'ir> {
 #[template(path = "partial_types.py.j2", escape = "none")]
 pub(crate) struct PythonStreamTypes<'ir> {
     partial_classes: Vec<PartialPythonClass<'ir>>,
+    is_pydantic_2: bool,
     structural_recursive_alias_cycles: Vec<PythonTypeAlias<'ir>>,
 }
 
@@ -68,11 +70,12 @@ impl<'ir> TryFrom<(&'ir IntermediateRepr, &'_ crate::GeneratorArgs)> for PythonT
     type Error = anyhow::Error;
 
     fn try_from(
-        (ir, _): (&'ir IntermediateRepr, &'_ crate::GeneratorArgs),
+        (ir, gen): (&'ir IntermediateRepr, &'_ crate::GeneratorArgs),
     ) -> Result<PythonTypes<'ir>> {
         Ok(PythonTypes {
             enums: ir.walk_enums().map(PythonEnum::from).collect::<Vec<_>>(),
             classes: ir.walk_classes().map(PythonClass::from).collect::<Vec<_>>(),
+            is_pydantic_2: matches!(gen.client_type, baml_types::GeneratorOutputType::PythonPydantic),
             structural_recursive_alias_cycles: {
                 let mut cycles = ir
                     .walk_alias_cycles()
@@ -160,12 +163,13 @@ impl<'ir> From<Walker<'ir, (&'ir String, &'ir FieldType)>> for PythonTypeAlias<'
 impl<'ir> TryFrom<(&'ir IntermediateRepr, &'_ crate::GeneratorArgs)> for PythonStreamTypes<'ir> {
     type Error = anyhow::Error;
 
-    fn try_from((ir, _): (&'ir IntermediateRepr, &'_ crate::GeneratorArgs)) -> Result<Self> {
+    fn try_from((ir, gen): (&'ir IntermediateRepr, &'_ crate::GeneratorArgs)) -> Result<Self> {
         Ok(Self {
             partial_classes: ir
                 .walk_classes()
                 .map(PartialPythonClass::from)
                 .collect::<Vec<_>>(),
+            is_pydantic_2: matches!(gen.client_type, baml_types::GeneratorOutputType::PythonPydantic),
             structural_recursive_alias_cycles: {
                 let mut cycles = ir
                     .walk_alias_cycles()

engine/language_client_codegen/src/python/mod.rs

@@ -119,6 +119,7 @@ struct InlinedBaml {
 pub(crate) fn generate(
     ir: &IntermediateRepr,
     generator: &crate::GeneratorArgs,
+    legacy_pydantic: bool,
 ) -> Result<IndexMap<PathBuf, String>> {
     let mut collector = FileCollector::<PythonLanguageFeatures>::new();
 
@@ -587,7 +588,7 @@ client<llm> GPT35 {
             true,
             GeneratorDefaultClientMode::Async,
             Vec::new(),
-            Some(GeneratorOutputType::PythonPydantic),
+            GeneratorOutputType::PythonPydantic,
             None,
             None,
         )
@@ -600,7 +601,7 @@ client<llm> GPT35 {
     fn generate_streaming_python() {
         let ir = mk_ir();
         let generator_args = mk_gen();
-        let res = generate(&ir, &generator_args).unwrap();
+        let res = generate(&ir, &generator_args, false).unwrap();
         let partial_types = res.get(&PathBuf::from("partial_types.py")).unwrap();
         let async_client = res.get(&PathBuf::from("async_client.py")).unwrap();
         //eprintln!("{}", partial_types);

engine/language_client_codegen/src/python/templates/async_client.py.j2

@@ -1,5 +1,5 @@
-from typing import Any, Dict, List, Optional, TypeVar, Union, TypedDict, Type, Literal, cast
-from typing_extensions import NotRequired
+from typing import Any, Dict, List, Optional, TypeVar, Union, TypedDict, Type, cast
+from typing_extensions import NotRequired, Literal
 import pprint
 
 import baml_py