Using datamode-code-generator as a Module

datamodel-code-generator is a CLI tool, but it can also be used as a module.

You can call this code-generator in your python code.

How to use it as module

You can generate models with datamodel_code_generator.generate using parameters that match the arguments provided to the CLI tool. The generated files can be written to and read from the Path object supplied to output.

In the below example, we use a file in a TemporaryDirectory to store our output.

Installation

pip install 'datamodel-code-generator[http]'

Example

from pathlib import Path
from tempfile import TemporaryDirectory
from datamodel_code_generator import InputFileType, generate
from datamodel_code_generator import DataModelType

json_schema: str = """{
    "type": "object",
    "properties": {
        "number": {"type": "number"},
        "street_name": {"type": "string"},
        "street_type": {"type": "string",
                        "enum": ["Street", "Avenue", "Boulevard"]
                        }
    }
}"""

with TemporaryDirectory() as temporary_directory_name:
    temporary_directory = Path(temporary_directory_name)
    output = Path(temporary_directory / 'model.py')
    generate(
        json_schema,
        input_file_type=InputFileType.JsonSchema,
        input_filename="example.json",
        output=output,
        # set up the output model types
        output_model_type=DataModelType.PydanticV2BaseModel,
    )
    model: str = output.read_text()
print(model)

The result of print(model):

# generated by datamodel-codegen:
#   filename:  example.json
#   timestamp: 2020-12-21T08:01:06+00:00

from __future__ import annotations

from enum import Enum
from typing import Optional

from pydantic import BaseModel


class StreetType(Enum):
    Street = 'Street'
    Avenue = 'Avenue'
    Boulevard = 'Boulevard'


class Model(BaseModel):
    number: Optional[float] = None
    street_name: Optional[str] = None
    street_type: Optional[StreetType] = None

Also, you can call parser directly

from datamodel_code_generator import DataModelType, PythonVersion
from datamodel_code_generator.model import get_data_model_types
from datamodel_code_generator.parser.jsonschema import JsonSchemaParser

json_schema: str = """{
    "type": "object",
    "properties": {
        "number": {"type": "number"},
        "street_name": {"type": "string"},
        "street_type": {"type": "string",
                        "enum": ["Street", "Avenue", "Boulevard"]
                        }
    }
}"""


data_model_types = get_data_model_types(
    DataModelType.PydanticV2BaseModel,
    target_python_version=PythonVersion.PY_311
)
parser = JsonSchemaParser(
   json_schema,
   data_model_type=data_model_types.data_model,
   data_model_root_type=data_model_types.root_model,
   data_model_field_type=data_model_types.field_model,
   data_type_manager_type=data_model_types.data_type_manager,
   dump_resolve_reference_action=data_model_types.dump_resolve_reference_action,
                       )
result = parser.parse()
print(result)
 ```

The result of `print(model)`:
```python
from __future__ import annotations

from enum import Enum
from typing import Optional

from pydantic import BaseModel


class StreetType(Enum):
    Street = 'Street'
    Avenue = 'Avenue'
    Boulevard = 'Boulevard'


class Model(BaseModel):
    number: Optional[float] = None
    street_name: Optional[str] = None
    street_type: Optional[StreetType] = None

Why doesn't datamodel_code_generator.generate return a string?

The above example schema only generates a single python module, but a single schema may generate multiple modules. There is no way to represent these modules as a single string, so the generate method returns None.

Note that the output parameter can take any Path object, which includes both file and directory paths. If a file name is provided and multiple modules are generated, generate will raise a datamodel_code_gen.Error exception.

If multiple modules are generated, you will need to walk through the supplied output directory to find all of them.