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pytypeinput

Extract structured metadata from Python type hints for building UIs.

Quick Example

from dataclasses import dataclass
from pytypeinput import Field, Annotated, Label, Description, PatternMessage, analyze_dataclass

@dataclass
class User:
    username: Annotated[
        str,
        Field(min_length=3, max_length=20, pattern=r'^[a-zA-Z0-9_]+$'),
        Label("Username"),
        Description("Choose a unique username (letters, numbers, underscore only)"),
        PatternMessage("Username can only contain letters, numbers, and underscores.")
    ]
    age: Annotated[int, Field(ge=18, le=120)]
    bio: str | None = None

# Extract metadata
params = analyze_dataclass(User)

# Now you have structured data for each field:
print(params[0].name)           # "username"
print(params[0].param_type)     # str
print(params[0].constraints)    # Field(min_length=3, max_length=20, pattern=...)
print(params[0].ui.label)       # "Username"
print(params[0].ui.description) # "Choose a unique username..."

print(params[1].name)           # "age"
print(params[1].constraints)    # Field(ge=18, le=120)

print(params[2].name)           # "bio"
print(params[2].optional)       # OptionalMetadata(enabled=False)

HTML Renderer Demo

The HTML renderer generates this interactive form from the User class:

Try the validation:

  • Username: 3-20 characters, letters/numbers/underscore only
  • Age must be 18-120
  • Bio is optional (toggle it on/off)

What Can You Analyze?

pytypeinput works with functions, dataclasses, Pydantic models, classes, and standalone types: 

from pytypeinput import analyze_function, analyze_dataclass, analyze_pydantic_model, analyze_class_init, analyze_type

# Functions
def create_user(username: str, age: int):
    pass
params = analyze_function(create_user)

# Dataclasses
@dataclass
class User:
    username: str
    age: int
params = analyze_dataclass(User)

# Pydantic Models
from pydantic import BaseModel
class User(BaseModel):
    username: str
    age: int
params = analyze_pydantic_model(User)

# Class __init__
class User:
    def __init__(self, username: str, age: int):
        pass
params = analyze_class_init(User)

# Standalone Types
Username = Annotated[str, Field(min_length=3)]
param = analyze_type(Username, name="username")

Installation

Core only: 

pip install pytypeinput
With HTML renderer: 
pip install pytypeinput[html]

Documentation

Type System:

  • Basic Types - int, float, str, bool, date, time
  • Special Types - Email, Color, File, ImageFile, etc.
  • Lists - list[Type] with item and list-level validation
  • Optionals - Type | None with toggle switches
  • Choices - Literal, Enum, Dropdown(func)

Validation & UI:

  • Constraints - Field(min=, max=, pattern=) for validation
  • UI Metadata - Custom labels, descriptions, placeholders, sliders

Renderers:

Reference: