fix!: python models not handling circular model dependencies (#1946)

docs/languages/Python.md

@@ -2,6 +2,8 @@
 
 There are special use-cases that each language supports; this document pertains to **Python models**.
 
+The generated Python models require at least v[3.7](https://docs.python.org/release/3.7.0/).
+
 <!-- toc is generated with GitHub Actions do not remove toc markers -->
 
 <!-- toc -->

docs/migrations/version-3-to-4.md

@@ -93,6 +93,8 @@ Console.WriteLine(dateTime2);
 
 ## Python
 
+Models are aiming to be >= v3.7 compliant.
+
 ### Pydantic now follows v2 instead of v1
 
 Reference: https://docs.pydantic.dev/2.6/migration/
@@ -104,7 +106,7 @@ class Message(BaseModel):
   identifier: str = Field(description='''The Identifier for the Message''')
 ```
 
-In Modelina 3 this used is rendered as:
+In Modelina v3 this used is rendered as:
 
 ```python
 class Message(BaseModel):
@@ -218,6 +220,10 @@ class Address:
     return self._street_name
 ```
 
+### Import style deprecation
+
+All models are from this point onwards imported using explicit styles `from . import ${model.name}` to allow for circular model dependencies to work. This means that the option `importsStyle` is deprecated and is no longer in use. It will be removed at some point in the future. 
+
 ## Go
 
 ### File names

examples/generate-python-complete-models/__snapshots__/index.spec.ts.snap

@@ -2,8 +2,9 @@
 
 exports[`Should be able to render python models and should generate \`implicit\` or \`explicit\` imports for models implementing referenced types: nested-model 1`] = `
 Array [
-  "
+  "from __future__ import annotations
 from typing import Any, Dict
+
 class ObjProperty: 
   def __init__(self, input: Dict):
     if 'number' in input:
@@ -30,8 +31,9 @@ class ObjProperty:
 
 exports[`Should be able to render python models and should generate \`implicit\` or \`explicit\` imports for models implementing referenced types: nested-model 2`] = `
 Array [
-  "
+  "from __future__ import annotations
 from typing import Any, Dict
+
 class ObjProperty: 
   def __init__(self, input: Dict):
     if 'number' in input:
@@ -58,14 +60,15 @@ class ObjProperty:
 
 exports[`Should be able to render python models and should generate \`implicit\` or \`explicit\` imports for models implementing referenced types: root-model-explicit-import 1`] = `
 Array [
-  "from ObjProperty import ObjProperty
+  "from __future__ import annotations
 from typing import Any, Dict
+from . import ObjProperty
 class Root: 
   def __init__(self, input: Dict):
     if 'email' in input:
       self._email: str = input['email']
     if 'obj_property' in input:
-      self._obj_property: ObjProperty = ObjProperty(input['obj_property'])
+      self._obj_property: ObjProperty.ObjProperty = ObjProperty.ObjProperty(input['obj_property'])
 
   @property
   def email(self) -> str:
@@ -75,25 +78,26 @@ class Root:
     self._email = email
 
   @property
-  def obj_property(self) -> ObjProperty:
+  def obj_property(self) -> ObjProperty.ObjProperty:
     return self._obj_property
   @obj_property.setter
-  def obj_property(self, obj_property: ObjProperty):
+  def obj_property(self, obj_property: ObjProperty.ObjProperty):
     self._obj_property = obj_property
 ",
 ]
 `;
 
 exports[`Should be able to render python models and should generate \`implicit\` or \`explicit\` imports for models implementing referenced types: root-model-implicit-import 1`] = `
 Array [
-  "from ObjProperty import ObjProperty
+  "from __future__ import annotations
 from typing import Any, Dict
+from . import ObjProperty
 class Root: 
   def __init__(self, input: Dict):
     if 'email' in input:
       self._email: str = input['email']
     if 'obj_property' in input:
-      self._obj_property: ObjProperty = ObjProperty(input['obj_property'])
+      self._obj_property: ObjProperty.ObjProperty = ObjProperty.ObjProperty(input['obj_property'])
 
   @property
   def email(self) -> str:
@@ -103,10 +107,10 @@ class Root:
     self._email = email
 
   @property
-  def obj_property(self) -> ObjProperty:
+  def obj_property(self) -> ObjProperty.ObjProperty:
     return self._obj_property
   @obj_property.setter
-  def obj_property(self, obj_property: ObjProperty):
+  def obj_property(self, obj_property: ObjProperty.ObjProperty):
     self._obj_property = obj_property
 ",
 ]

examples/generate-python-pydantic-models/__snapshots__/index.spec.ts.snap

@@ -6,7 +6,7 @@ Array [
   optional_field: Optional[str] = Field(description='''this field is optional''', default=None, serialization_alias='optionalField')
   required_field: str = Field(description='''this field is required''', serialization_alias='requiredField')
   no_description: Optional[str] = Field(default=None, serialization_alias='noDescription')
-  options: Optional[Options] = Field(default=None, serialization_alias='options')
+  options: Optional[Options.Options] = Field(default=None, serialization_alias='options')
 ",
 ]
 `;

src/generators/python/PythonConstrainer.ts

@@ -14,7 +14,7 @@ export const PythonDefaultTypeMapping: PythonTypeMapping = {
     return constrainedModel.name;
   },
   Reference({ constrainedModel }): string {
-    return constrainedModel.name;
+    return `${constrainedModel.name}.${constrainedModel.name}`;
   },
   Any({ dependencyManager }): string {
     dependencyManager.addDependency('from typing import Any');

src/generators/python/PythonDependencyManager.ts

@@ -14,10 +14,7 @@ export class PythonDependencyManager extends AbstractDependencyManager {
    * Simple helper function to render a dependency based on the module system that the user defines.
    */
   renderDependency(model: ConstrainedMetaModel): string {
-    const useExplicitImports = this.options.importsStyle === 'explicit';
-    return `from ${useExplicitImports ? '.' : ''}${model.name} import ${
-      model.name
-    }`;
+    return `from . import ${model.name}`;
   }
 
   /**
@@ -26,14 +23,24 @@ export class PythonDependencyManager extends AbstractDependencyManager {
    * For example `from typing import Dict` and `from typing import Any` would form a single import `from typing import Dict, Any`
    */
   renderDependencies(): string[] {
+    let dependenciesToRender = this.dependencies;
+    dependenciesToRender =
+      this.mergeIndividualDependencies(dependenciesToRender);
+    dependenciesToRender = this.moveFutureDependency(dependenciesToRender);
+    return dependenciesToRender;
+  }
+
+  /**
+   * Split up each dependency that matches `from x import y` and keep everything else as is.
+   *
+   * Merge all `y` together and make sure they are unique and render the dependency as `from x import y1, y2, y3`
+   */
+  private mergeIndividualDependencies(
+    individualDependencies: string[]
+  ): string[] {
     const importMap: Record<string, string[]> = {};
     const dependenciesToRender = [];
-    /**
-     * Split up each dependency that matches `from x import y` and keep everything else as is.
-     *
-     * Merge all `y` together and make sure they are unique and render the dependency as `from x import y1, y2, y3`
-     */
-    for (const dependency of this.dependencies) {
+    for (const dependency of individualDependencies) {
       const regex = /from ([A-Za-z0-9]+) import ([A-Za-z0-9,\s]+)/g;
       const matches = regex.exec(dependency);
 
@@ -58,4 +65,19 @@ export class PythonDependencyManager extends AbstractDependencyManager {
     }
     return dependenciesToRender;
   }
+
+  /**
+   * If you import `from __future__ import x` it always has to be rendered first
+   */
+  private moveFutureDependency(individualDependencies: string[]): string[] {
+    const futureDependencyIndex = individualDependencies.findIndex((element) =>
+      element.includes('__future__')
+    );
+    if (futureDependencyIndex !== -1) {
+      individualDependencies.unshift(
+        individualDependencies.splice(futureDependencyIndex, 1)[0]
+      );
+    }
+    return individualDependencies;
+  }
 }

src/generators/python/PythonGenerator.ts

@@ -39,6 +39,9 @@ export interface PythonOptions
   extends CommonGeneratorOptions<PythonPreset, PythonDependencyManager> {
   typeMapping: TypeMapping<PythonOptions, PythonDependencyManager>;
   constraints: Constraints<PythonOptions>;
+  /**
+   * @deprecated no longer in use - we had to switch to using explicit import style, always to support circular model dependencies.
+   */
   importsStyle: 'explicit' | 'implicit';
 }
 export type PythonConstantConstraint = ConstantConstraint<PythonOptions>;
@@ -62,7 +65,7 @@ export class PythonGenerator extends AbstractGenerator<
     defaultPreset: PYTHON_DEFAULT_PRESET,
     typeMapping: PythonDefaultTypeMapping,
     constraints: PythonDefaultConstraints,
-    importsStyle: 'implicit',
+    importsStyle: 'explicit',
     // Temporarily set
     dependencyManager: () => {
       return {} as PythonDependencyManager;
@@ -206,8 +209,8 @@ export class PythonGenerator extends AbstractGenerator<
       .map((model) => {
         return dependencyManagerToUse.renderDependency(model);
       });
-    const outputContent = `${modelDependencies.join('\n')}
-${outputModel.dependencies.join('\n')}
+    const outputContent = `${outputModel.dependencies.join('\n')}
+${modelDependencies.join('\n')}
 ${outputModel.result}`;
     return RenderOutput.toRenderOutput({
       result: outputContent,

src/generators/python/presets/Pydantic.ts

@@ -21,30 +21,34 @@ const PYTHON_PYDANTIC_CLASS_PRESET: ClassPresetType<PythonOptions> = {
       `class ${model.name}(BaseModel):`
     );
   },
-  property(params) {
-    let type = params.property.property.type;
-    const propertyName = params.property.propertyName;
+  property({ property, model, renderer }) {
+    let type = property.property.type;
+    const propertyName = property.propertyName;
 
-    if (params.property.property instanceof ConstrainedUnionModel) {
-      const unionTypes = params.property.property.union.map(
+    if (property.property instanceof ConstrainedUnionModel) {
+      const unionTypes = property.property.union.map(
         (unionModel) => unionModel.type
       );
       type = `Union[${unionTypes.join(', ')}]`;
     }
 
-    if (!params.property.required) {
+    if (!property.required) {
       type = `Optional[${type}]`;
     }
+    type = renderer.renderPropertyType({
+      modelType: model.type,
+      propertyType: type
+    });
 
-    const description = params.property.property.originalInput['description']
-      ? `description='''${params.property.property.originalInput['description']}'''`
+    const description = property.property.originalInput['description']
+      ? `description='''${property.property.originalInput['description']}'''`
       : undefined;
-    const defaultValue = params.property.required ? undefined : 'default=None';
-    const jsonAlias = `serialization_alias='${params.property.unconstrainedPropertyName}'`;
+    const defaultValue = property.required ? undefined : 'default=None';
+    const jsonAlias = `serialization_alias='${property.unconstrainedPropertyName}'`;
     let exclude = undefined;
     if (
-      params.property.property instanceof ConstrainedDictionaryModel &&
-      params.property.property.serializationType === 'unwrap'
+      property.property instanceof ConstrainedDictionaryModel &&
+      property.property.serializationType === 'unwrap'
     ) {
       exclude = 'exclude=True';
     }