> ## Documentation Index > Fetch the complete documentation index at: https://docs.dottxt.ai/llms.txt > Use this file to discover all available pages before exploring further. # Form Processing > Normalize unstructured form text into a strict backend payload with validation-friendly fields. Users type addresses with inconsistent formatting, phone numbers with or without country codes, and shipping preferences in plain English. If you pass this text to your backend as-is, you need normalization logic, validation logic, and error handling for every possible format variation. Schema-constrained generation does this normalization at extraction time: the model reads the messy input and produces a clean, typed object that conforms to your backend's expectations. ## Goal Convert mixed-quality user submissions into a normalized order payload with correct types, validated formats, and consistent structure, ready for your order creation API. ## Schema contract ```json JSON Schema theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}} { "type": "object", "properties": { "customer": { "type": "object", "properties": { "name": { "type": "string", "minLength": 1, "maxLength": 100 }, "email": { "type": "string", "format": "email" }, "phone": { "type": ["string", "null"], "pattern": "^\\+?[1-9][0-9]{7,14}$" } }, "required": ["name", "email", "phone"], "additionalProperties": false }, "shipping": { "type": "object", "properties": { "method": { "type": "string", "enum": ["standard", "express"] }, "address_line1": { "type": "string", "minLength": 1, "maxLength": 120 }, "city": { "type": "string", "minLength": 1, "maxLength": 80 }, "postal_code": { "type": "string", "minLength": 3, "maxLength": 20 }, "country": { "type": "string", "pattern": "^[A-Z]{2}$" } }, "required": ["method", "address_line1", "city", "postal_code", "country"], "additionalProperties": false }, "notes": { "type": ["string", "null"], "maxLength": 300 } }, "required": ["customer", "shipping"], "additionalProperties": false } ``` ```python Pydantic theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}} from typing import Literal from pydantic import BaseModel, ConfigDict, EmailStr, Field class Customer(BaseModel): model_config = ConfigDict(extra="forbid") name: str = Field(..., min_length=1, max_length=100) email: EmailStr phone: str | None = Field(..., pattern=r"^\+?[1-9][0-9]{7,14}$") class Shipping(BaseModel): model_config = ConfigDict(extra="forbid") method: Literal["standard", "express"] address_line1: str = Field(..., min_length=1, max_length=120) city: str = Field(..., min_length=1, max_length=80) postal_code: str = Field(..., min_length=3, max_length=20) country: str = Field(..., pattern=r"^[A-Z]{2}$") class OrderPayload(BaseModel): model_config = ConfigDict(extra="forbid") customer: Customer shipping: Shipping notes: str | None = Field(None, max_length=300) ``` ```typescript Zod theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}} import { z } from "zod"; const orderPayloadSchema = z.object({ customer: z.object({ name: z.string().min(1).max(100), email: z.string().email(), phone: z.string().regex(/^\+?[1-9][0-9]{7,14}$/).nullable(), }).strict(), shipping: z.object({ method: z.enum(["standard", "express"]), address_line1: z.string().min(1).max(120), city: z.string().min(1).max(80), postal_code: z.string().min(3).max(20), country: z.string().regex(/^[A-Z]{2}$/), }).strict(), notes: z.string().max(300).nullable().optional(), }).strict(); ``` ```bash curl theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}} curl https://api.dottxt.ai/v1/chat/completions \ -H "Authorization: Bearer $DOTTXT_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "model": "openai/gpt-oss-20b", "messages": [{ "role": "user", "content": "Ship this to 10 Main Street, Austin 78701 US. Use express please. Name: Alice Johnson, email alice@acme.com. No phone." }], "response_format": { "type": "json_schema", "json_schema": { "name": "order_payload", "schema": { "type": "object", "properties": { "customer": { "type": "object", "properties": { "name": { "type": "string", "minLength": 1, "maxLength": 100 }, "email": { "type": "string", "format": "email" }, "phone": { "type": ["string", "null"], "pattern": "^\\+?[1-9][0-9]{7,14}$" } }, "required": ["name", "email", "phone"], "additionalProperties": false }, "shipping": { "type": "object", "properties": { "method": { "type": "string", "enum": ["standard", "express"] }, "address_line1": { "type": "string", "minLength": 1, "maxLength": 120 }, "city": { "type": "string", "minLength": 1, "maxLength": 80 }, "postal_code": { "type": "string", "minLength": 3, "maxLength": 20 }, "country": { "type": "string", "pattern": "^[A-Z]{2}$" } }, "required": ["method", "address_line1", "city", "postal_code", "country"], "additionalProperties": false }, "notes": { "type": ["string", "null"], "maxLength": 300 } }, "required": ["customer", "shipping"], "additionalProperties": false } } } }' ``` ## Example input ```text theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}} Ship this to 10 Main Street, Austin 78701 US. Use express please. I'm Alice Johnson, email alice@acme.com. No phone. ``` ## Example output ```json theme={"theme":{"light":"vitesse-light","dark":"vitesse-dark"}} { "customer": { "name": "Alice Johnson", "email": "alice@acme.com", "phone": null }, "shipping": { "method": "express", "address_line1": "10 Main Street", "city": "Austin", "postal_code": "78701", "country": "US" } } ``` ## Implementation tips * **Nullable for "asked but absent."** The user explicitly said "no phone," so `phone` is `null` rather than omitted. Your backend can distinguish "no phone provided" from "phone not asked," which is useful for follow-up workflows. * **Enums for controlled vocabulary.** `method` is `"standard"` or `"express"`, not `"fast"`, `"next day"`, or `"ASAP"`. The enum forces normalization so your shipping logic doesn't need string matching. * **Pattern for format enforcement.** The `country` field uses `"^[A-Z]{2}$"` so the model produces `"US"` instead of `"United States"`, `"usa"`, or `"U.S.A."`. The same idea applies to `phone`: the E.164-like pattern ensures a format your telephony API accepts. * **`additionalProperties: false`** prevents the model from forwarding raw user text as extra fields, which could leak PII into systems that don't expect it. ## Related docs * [Optional vs Null](/json-schema/optional-vs-null): distinguish "not provided" from "explicitly absent" * [Optional fields](/json-schema/optional-fields): fields the model can omit entirely * [String bounds](/json-schema/string-bounds): control length, format, and regex on form fields * [Object reference](/json-schema/reference/object) | [String reference](/json-schema/reference/string)