Fix incorrect relative imports with --use-exact-imports and --collapse-root-models (#2996)

* Fix incorrect relative imports with --use-exact-imports and --collapse-root-models

* Generate root __init__.py for multi-directory output packages

Author: koxudaxi

src/datamodel_code_generator/parser/base.py

@@ -2079,6 +2079,8 @@ def __collapse_root_models(  # noqa: PLR0912, PLR0914, PLR0915
                         if d.reference is None:
                             continue
                         from_, import_ = full_path = relative(model.module_name, d.full_name)
+                        if imports.use_exact:
+                            from_, import_ = full_path = exact_import(from_, import_, d.reference.short_name)
                         if from_ and import_:
                             alias = scoped_model_resolver.add(full_path, import_)
                             d.alias = (
@@ -3393,6 +3395,12 @@ def parse(  # noqa: PLR0913, PLR0914, PLR0917
 
         self._finalize_modules(contexts, unused_models, model_to_module_models, module_to_import)
 
+        root_init: ModulePath = ("__init__.py",)
+        if root_init not in results:
+            top_level_dirs = {k[0] for k in results if len(k) >= 2}  # noqa: PLR2004
+            if len(top_level_dirs) > 1:
+                results[root_init] = Result(body="")
+
         future_imports = self.imports.extract_future()
         future_imports_str = str(future_imports)
 

tests/data/expected/main/jsonschema/exact_imports_collapse_root_models/__init__.py

@@ -0,0 +1,2 @@
+# generated by datamodel-codegen:
+#   filename:  exact_imports_collapse_root_models

tests/data/expected/main/jsonschema/exact_imports_collapse_root_models/data/ReflectionSetData.py

@@ -0,0 +1,15 @@
+# generated by datamodel-codegen:
+#   filename:  data/ReflectionSetData.json
+
+from __future__ import annotations
+
+from pydantic import BaseModel, Field
+
+from ..datatypes.BarStats import BarStats
+from ..datatypes.FooStats import FooStats
+
+
+class ReflectionSetData(BaseModel):
+    stats: FooStats | None = None
+    stats_list: list[FooStats] | None = None
+    stats_collection: list[BarStats] | None = Field(None, title='BarStatsList')

tests/data/expected/main/jsonschema/exact_imports_collapse_root_models/data/__init__.py

@@ -0,0 +1,2 @@
+# generated by datamodel-codegen:
+#   filename:  exact_imports_collapse_root_models

tests/data/expected/main/jsonschema/exact_imports_collapse_root_models/datatypes/BarStats.py

@@ -0,0 +1,10 @@
+# generated by datamodel-codegen:
+#   filename:  datatypes/BarStats.json
+
+from __future__ import annotations
+
+from pydantic import BaseModel
+
+
+class BarStats(BaseModel):
+    value: float | None = None

tests/data/expected/main/jsonschema/exact_imports_collapse_root_models/datatypes/FooStats.py

@@ -0,0 +1,11 @@
+# generated by datamodel-codegen:
+#   filename:  datatypes/FooStats.json
+
+from __future__ import annotations
+
+from pydantic import BaseModel
+
+
+class FooStats(BaseModel):
+    count: int | None = None
+    average: float | None = None

tests/data/expected/main/jsonschema/exact_imports_collapse_root_models/datatypes/__init__.py

@@ -0,0 +1,2 @@
+# generated by datamodel-codegen:
+#   filename:  exact_imports_collapse_root_models

tests/data/jsonschema/exact_imports_collapse_root_models/data/ReflectionSetData.json

@@ -0,0 +1,23 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "title": "ReflectionSetData",
+  "type": "object",
+  "properties": {
+    "stats": {
+      "allOf": [
+        {
+          "$ref": "../datatypes/FooStats.json"
+        }
+      ]
+    },
+    "stats_list": {
+      "type": "array",
+      "items": {
+        "$ref": "../datatypes/FooStats.json"
+      }
+    },
+    "stats_collection": {
+      "$ref": "../datatypes/BarStatsList.json"
+    }
+  }
+}

tests/data/jsonschema/exact_imports_collapse_root_models/datatypes/BarStats.json

@@ -0,0 +1,10 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "title": "BarStats",
+    "type": "object",
+    "properties": {
+        "value": {
+            "type": "number"
+        }
+    }
+}

tests/data/jsonschema/exact_imports_collapse_root_models/datatypes/BarStatsList.json

@@ -0,0 +1,8 @@
+{
+    "$schema": "http://json-schema.org/draft-07/schema#",
+    "title": "BarStatsList",
+    "type": "array",
+    "items": {
+        "$ref": "BarStats.json"
+    }
+}