Enhancing Pydantic with Programmatic Titles

Pydantic is a popular Python library used for building robust, scalable, and maintainable data models. It provides a simple and intuitive way to define data structures, validate data, and generate JSON schemas. One of the key features of Pydantic is its ability to specify titles for models and fields, which is useful for generating human-readable documentation and improving the overall user experience.

Current Limitations

Currently, Pydantic allows specifying a string literal for the title value used in the exported JSON schema. For BaseModel, this can be accomplished via the Config class:

from pydantic import BaseModel

class MyDataClass(BaseModel):
    class Config:
        title = "My Data Class"

Similarly, for BaseModel fields, an explicit title string can be specified with a Field instance:

from pydantic import BaseModel, Field
from typing import List

class MyDataClass(BaseModel):
    matchCriteria: List[str] = Field(default_factory=list, title="Match Criteria")
    class Config:
        title = "My Data Class"

Proposed Solution

To enhance Pydantic's title specification functionality, we propose introducing a title_generator class attribute in the Config class and a title_generator parameter in the Field constructor. This would allow developers to specify a Python callable that generates the title value programmatically.

The title_generator callable would take the BaseModel class name or field alias as an argument, enabling developers to create custom title generation logic. For example:

import re
from pydantic import BaseModel

def make_title(name: str):
    def _capitalize(v: str):
        return v[0].upper() + v[1:]
    return re.sub(r"(?<=[a-z])([A-Z])", r" \1", _capitalize(name))

class MyDataClass(BaseModel):
    matchCriteria: List[str] = Field(default_factory=list, title_generator=make_title)
    class Config:
        title_generator = make_title

This would result in a JSON schema with programmatically generated titles:

{
    "title": "My Data Class",
    "type": "object",
    "properties": {
        "matchCriteria": {
            "title": "Match Criteria",
            "type": "array",
            "items": {
                "type": "string"
            }
        }
    }
}

Benefits

The proposed solution offers several benefits, including:

• Improved flexibility: Developers can create custom title generation logic using Python callables.
• Increased readability: Programmatically generated titles can improve the readability of JSON schemas and documentation.
• Reduced maintenance: Titles can be updated automatically when model or field names change.

Conclusion

Adding a title_generator class attribute and parameter to Pydantic's Config class and Field constructor, respectively, would provide a powerful and flexible way to specify titles for models and fields. This enhancement would improve the overall user experience, reduce maintenance efforts, and increase the readability of JSON schemas and documentation. Learn more about Pydantic and its features. For more information on JSON schema generation, visit the official JSON schema website.