@formknot/core

Framework-neutral schema, validation, and conditional-logic engine for FormKnot — connect fields, rules, and validation into dynamic forms.

This package has no React or DOM dependency. It defines the JSON-serializable FormKnotSchema model and the pure functions that validate, migrate, and evaluate it. @formknot/react and @formknot/builder-react are both built on top of it.

Install

npm install @formknot/core

What's in here

• Types — FormKnotSchema, FormKnotField (discriminated union per field type), FormKnotValidationRule, FormKnotFieldCondition, FormKnotConditionGroup.
• Schema validation — validateFormKnotSchema(schema) checks structure (via AJV), uniqueness of ids/names, option/validation-rule compatibility, condition field references, circular conditional dependencies, and unsafe object keys. Returns path-based errors.
• Data validation — validateFormData(schema, values, { validators }) runs built-in rules (required, email, minLength, maxLength, min, max, pattern) and custom sync/async validators, honoring conditional visibility.
• Conditions — evaluateFieldConditions, evaluateSchemaConditions, findCircularConditionDependencies are pure functions with no framework dependency.
• Registries — createValidatorRegistry() maps a validator id (referenced from a schema) to an implementation that is never itself stored in the schema. createFieldRegistry() is the framework-neutral field-type registry contract.
• Migrations & serialization — migrateSchema, exportSchema, importSchema (never throws; reports errors instead).
• Safe object utilities — safeClone, safeGet, safeSet, safeJsonParse strip __proto__/prototype/constructor keys to guard against prototype pollution from imported JSON.

Example

import { createEmptySchema, createField, validateFormKnotSchema, validateFormData } from "@formknot/core";

const schema = createEmptySchema({ title: "Signup" });
schema.fields.push(createField("email", { name: "email", label: "Email", required: true }));

const { valid, errors } = validateFormKnotSchema(schema);

const result = await validateFormData(schema, { email: "not-an-email" });

Part of the FormKnot monorepo

This package is published from dev-saurav61295/formknot, alongside @formknot/react and @formknot/builder-react. See the root README for the full architecture and CONTRIBUTING.md to contribute.

License

MIT