Build a Yup schema from a JSON Schema, GraphQL schema (type definition) or any other similar type/class and field/properties model or schema :)
The builder currently supports the most commonly used JSON Schema layout and GraphQL type definition exports using graphSchemaToJson (see GraphQL schema).
It also supports some extra convenience schema properties that make it more "smooth" to define validation requirements declaratively (see below).
According to the JSON schema specs, you are free to add extra metadata to the field schema definitions beyond those supported "natively".
This library is built to be easy to customise or extend to suit individual developer needs. |Use any of the following customisation hooks to add custom features, circumvent missing functionality or bugs or extend any way you see fit. You can even use these hooks to support a different validator library, leveraging the generic schema validator builder infrastructure.
The most recent versions have more functionality but are still a bit unstable in some areas.
For a solid/stable version, try 1.9.16.
Install
npm install schema-to-yup -S or yarn add schema-to-yup
Use
const schema = {
$schema: "http://json-schema.org/draft-07/schema#",
$id: "http://example.com/person.schema.json",
title: "Person",
description: "A person",
type: "object",
properties: {
name: {
description: "Name of the person",
type: "string"
},
email: {
type: "string",
format: "email"
},
fooorbar: {
type: "string",
matches: "(foo|bar)"
},
age: {
description: "Age of person",
type: "number",
exclusiveMinimum: 0,
required: true
},
characterType: {
enum: ["good", "bad"],
enum_titles: ["Good", "Bad"],
type: "string",
title: "Type of people",
propertyOrder: 3
}
},
required: ["name", "email"]
};
const config = {
// for error messages...
errMessages: {
age: {
required: "A person must have an age"
},
email: {
required: "You must enter an email address",
format: "Not a valid email address"
}
}
};
const { buildYup } = require("schema-to-yup");
const yupSchema = buildYup(schema, config);
// console.dir(schema)
const valid = await yupSchema.isValid({
name: "jimmy",
age: 24
});
console.log({
valid
});
// => {valid: true}This would generate the following Yup validation schema:
const schema = yup.object().shape({
name: yup.string().required(),
age: yup
.number()
.required()
.positive()
});Note the "required": true for the age property (not natively supported by JSON schema).
Please note that this library does not currently resolve $ref (JSON Pointers) out of the box. You can use another library for that.
You could f.ex use json-schema-ref-parser to preprocess your schema. Also see:
By default, any property will be explicitly notRequired unless set to be required, either via required: true in the property constraint object or via the required list of properties of the object schema definition (of the property).
You can override the notRequired behavior by setting it on the new mode object of the configuration which can be used to control and fine-tune runtime behaviour.
const jsonSchema = {
title: "users",
type: "object",
properties: {
username: { type: "string" }
}
};const yupSchema = buildYup(jsonSchema, {
mode: {
notRequired: true // default setting
}
});
// will be valid since username is not required by default
const valid = yupSchema.validateSync({
foo: "dfds"
});const yupSchema = buildYup(jsonSchema, {
mode: {
notRequired: true // default setting
}
});
// will be invalid since username is required by default when notRequired mode is disabled
const valid = yupSchema.validateSync({
foo: "dfds"
});The new run time mode settings are demonstrated under sample-runs/mode
No validation error (prop not required unless explicitly specified):
$ npx babel-node sample-runs/modes/not-required-on.js
Validation error if not valid type:
$ npx babel-node sample-runs/modes/not-required-on.js
You can access the internal Yup shape, via shapeConfig on the yup schema returned by the buildYup schema builder function.
This allows you to easily mix and match to suit more advanced requirements.
const { buildYup } = require("json-schema-to-yup");
const { shapeConfig } = buildYup(json, config);
const schema = yup.object().shape({
...shapeConfig,
...customShapeConfig
});Currently the following schema types are supported:
arraybooleandatenumberobjectstring
strictdefaultnullablerequirednotRequiredoneOf(enum,anyOf)notOneOfwhenNEWisTypeNEWnullable(isNullable) NEW
ensurecompactitems(of)maxItems(max)minItems(min)itemsOf(of) NEW
No keys
maxDate(max)minDate(min)
integermoreThan(exclusiveMinimum)lessThan(exclusiveMaximum)positivenegativemin(minimum)max(maximum)truncateround
camelCaseconstantCasenoUnknown(propertyNames)
minLength(min)maxLength(max)pattern(matchesorregex)email(format: 'email')url(format: 'url')lowercaseuppercasetrim
For pattern (RegExp) you can additionally provide a flags property, such as flags: 'i'.
Will be converted to a regexp using new RegExp(pattern, flags)
This library currently does not come with built-in support for multi valued (list/array) type constraints such as ['string', 'null']
See Issue 52 for a discussion and current state.
To support this, you can either add your own logic for the toMultiType function/method of YupSchemaEntry or pass a custom factory method createMultiTypeValueResolver on the config object.
Sample code for multi type support (untested):
export const createPropertyValueHandler = (opts, config) => {
return new PropertyValueResolver(opts, config);
};
export class MyMultiTypeValueResolver extends MultiTypeValueResolver {
constructor(opts, config) {
this.propertyHandler = createPropertyValueHandler(opts, config);
}
resolve() {
const { value, name } = this;
let constraintListValue = this.normalizeValue(value); // ['string', 'null']
const multiTypePropSchema = constraintListValue.reduce(
(accSchema, constraintValue) => {
return this.resolvePropertyValue(constraintValue, accSchema);
},
null
);
return yup.mixed().test({
name,
exclusive: true,
params: {},
message: "${path} does not conform to all constraints defined",
test: val => {
return multiTypePropSchema.validateSync(val);
}
});
}
resolvePropertyValue(constraintValue, accSchema) {
const opts = {
...this.opts,
constraintValue
};
return this.propertyHandler.resolve(opts, this.config);
}
// expand/normalize to list of objects each with a valid type entry
normalizeList(multiTypeList) {
return multiTypeList.reduce((acc, entry) => {
acc.push(normalizedEntry);
return acc;
}, []);
}
normalizeTypeEntry(entry) {
if (!this.isStringType(entry)) return entry;
return { type: entry };
}
}You can pass in custom functions for the following kinds of type entry values
- object value, such as
{type: 'string'} - list value, such as
["string", "integer"]
The custom functions are:
toSingleType(yupSchemaEntryBuilder)toMultiType(yupSchemaEntryBuilder)
Each takes an instance yupSchemaEntryBuilder of YupSchemaEntry, which primarily holds the following properties of interest, that you can leverage in your custom handler logic
{
schema, key, name, value, type, obj, config;
}You can pass any custom typehandlers in a typeHandlers object as part of the config object passes. See setTypeHandlers() in entry.js for how this works internally.
function myCustomStringHandler = (obj, config) => {
// ... custom handler
// return yup type schema such as yup.string()
// with one or more constraints added
}
const yupSchema = buildYup(jsonSchema, {
typeHandlers: {
string: myCustomStringHandler
},
});This can be used to support special cases, to circumvent a bug or unexpected/unwarranted behaviour for one or more of the built-in type handlers etc. You can then use the built in classes as building blocks.
To control which constraints are enabled (executed), simply edit the typeEnabled getter on your type handler class. Here is the default typeEnabled getter for the YupDate (Date) type handler, which is configured to execute constraint handler functions: minDate and maxDate.
get typeEnabled() {
return ["minDate", "maxDate"];
}This can also be used to add custom handlers as described in the next section.
You can also add custom custraint handler functions directly via the config object as follows:
This can be used to override built in constraints or extend with your own.
A custom handler to validate a string formatted as a valid ip address might look something like this (presuming such a method is available on yup string). You can also use this with yup schema type extensions.
// takes the typehandler (such as YupString) instance as argument
const ipHandler = th => {
const constraintName = th.constraintNameFor("ip", "format");
const method = "ip";
th.addConstraint("ip", {
constraintValue: true,
constraintName,
method,
errName: method
});
};
const config = {
string: {
convert: {
ip: ipHandler
},
enabled: [
"ip", // custom
// built in
"normalize",
"minLength",
"maxLength",
"pattern",
"lowercase",
"uppercase",
"email",
"url",
"genericFormat"
]
}
// ... more configuration
};
buildYup(jsonSchema, config);Instead of using enabled with the full list, you can also use extends
extends: [
// custom additions
"ip",
// built in handlers all included automatically
]Note that if convert has entries and extends for the type configuration is not set (and no enabled list of constraints defined either) it will use all the entries in convert by default (ie. extends set to all keys).
We welcome feedback on how to better structure the config object to make it easy and intuitive to add run-time configuration to suit your needs.
This library supports using a custom constraint builder to add and build constraints. All factories are initialised in initHelpers and executed as the first step of convert (see mixed.js)
import { ConstraintBuilder } from "schema-to-yup";
class MyConstraintBuilder extends ConstraintBuilder {
constructor(typeHandler, opts = {}) {
super(typeHandler, opts);
// custom instance configuration
}
build(propName, opts) {
/// custom build logic
// returns new type validation handler (base) with built constraint added
return newBase;
}
addConstraint(propName, opts) {
// custom add constraint logic
return this.typeHandler;
}
// custom event handler
onConstraintAdded({ name, value }) {
// ...
return this.typeHandler;
}
}To use a custom constraint builder we recommend subclassing the ConstraintBuilder class that comes with the library. Then create a factory method thart can instanciate it.
const createConstraintBuilder = (typeHandler, config) => {
return new MyConstraintBuilder(typeHandler, config);
};
const config = {
createConstraintBuilder
// ... more configuration
};
buildYup(jsonSchema, config);Basic support for when conditions as requested and outlined in this issue is now included.
Work will continue in the when-condition branch.
Sample schema using simple when constraint:
const biggyJson = {
title: "biggy",
type: "object",
properties: {
isBig: {
type: "boolean"
},
count: {
type: "number",
when: {
isBig: {
is: true,
then: {
min: 5
}
}
}
}
}
};Sample valid and invalid values with respect to biggyJson schema
const bigJson = {
valid: {
isBig: true,
count: 5 // since isBig is set, must be >= 5
},
invalid: {
isBig: true,
count: 4 // since isBig is set, must be >= 5
}
};Currently basic support is included in [email protected] on npmjs
More advanced conditionals support will likely be included the next major release: 2.0.
You are welcome to continue the effort to support more conditional schema logic by continuing on this branch and making PRs.
Support for if then and else conditional JSON schema constraints can likely be added using an approach like the when condition (perhaps by transalating to equivalent: when, then and otherwise).
if- This keyword's value MUST be a valid JSON Schemathen- This keyword's value MUST be a valid JSON Schemaelse- This keyword's value MUST be a valid JSON Schema
See also json-schema-spec
You can now also override, extend or customize the when condition logic by passing in your own factory method for the config object entry createWhenCondition
const myWhenConditionFactoryFn = (opts = {}) => {
const { type, key, value, when, schema, properties, config } = opts;
// ...
};
const config = {
createWhenCondition: myWhenConditionFactoryFn
};
const schema = buildYup(nameJsonSchema, config);The best and easiest way to do this is to extend the WhenCondition class which contains most of the necessary infrastructure you can further build on.
See the src/conditions/legacy folder for the legacy 1.9.0 logic that works but has limited functionality.
Currently this library does not have built-in support for the additionalProperties feature of JSON schema as described here
{
"type": "object",
"properties": {
"number": { "type": "number" },
"street_name": { "type": "string" },
"street_type": { "type": "string",
"enum": ["Street", "Avenue", "Boulevard"]
}
},
"additionalProperties": { "type": "string" }
}See issue 55
Yup does not directly support this, so it would require some "hacking" to make it work.
You can extend YupBuilder to include custom logic to support additionalProperties
class YupBuilderWithSupportForAdditionalProperties extends YupBuilder {
additionalPropsToShape(opts, shape) {
// do your magic here using this.additionalProps
// make new yup constraint function calls on the incoming yup shape object
return shape;
}
}See the issue for ideas and hints on how to achieve support for this.
Here a more complete example of the variations currently possible
{
"title": "Person",
"description": "A person",
"type": "object",
"properties": {
"name": {
"description": "Name of the person",
"type": "string",
"required": true,
"matches": "[a-zA-Z- ]+",
"min": 3,
"maxLength": 40,
},
"age": {
"description": "Age of person",
"type": "integer",
"moreThan": 0,
"max": 130,
"default": 32,
"required": false,
"nullable": true
},
"birthday": {
"type": "date",
"min": "1-1-1900",
"maxDate": "1-1-2015"
},
"married": {
"type": "boolean"
},
"boss": {
"type": "object",
"noUnknown": [
"name"
],
"properties": {
"name": {
"type": "string",
"notOneOf": ["Dr. evil", "bad ass"]
}
}
},
"colleagues": {
"type": "array",
"items": {
"type": "object",
"propertyNames": [
"name"
],
"properties": {
"name": {
"type": "string"
}
}
}
},
"programming": {
"type": "object",
"properties": {
"languages": {
"type": "array",
"of": {
"type": "string",
"enum": ["javascript", "java", "C#"]
},
"min": 1,
"max": 3
}
}
}
}
}
}Nested object schema properties are supported.
See test/types/object/complex-schema.test.js
This library now also supports non JSON schema models. See the types/defaults mappings.
types/defaults/json-schema.js
module.exports {
getProps: obj => obj.properties,
getType: obj => obj.type,
getName: obj => obj.name || obj.title,
getConstraints: obj => obj,
isString: obj => obj.type === "string",
isArray: obj => obj.type === "array",
isInteger: obj => obj.type === "integer",
isBoolean: obj => obj.type === "boolean",
hasDateFormat: obj => ["date", "date-time"].find(t => t === obj.format),
isDate: obj => obj.type === "string" && defaults.hasDateFormat(obj.format),
isNumber: obj => obj.type === "number" || defaults.isInteger(obj.type),
isObject: obj => obj.type === "object",
isRequired: obj => obj.required
};This can be used to support any kind of schema, including JSN schema and GraphQL type definition schemas etc.
To support another model, such as GraphQL schema (type definitions) via graphSchemaToJson
Person:
{
Person: {
name: 'Person',
fields: {
name: {
type: 'String',
directives: {
constraints: {
minLength: 2
}
},
isNullable: false,
isList: false
}
}
directives: {},
type: 'Object',
implements: []
}
}Create a map of methods to match your model layout:
const typeDefConf = {
getProps: obj => obj.fields,
getType: obj => obj.type,
getName: obj => obj.name,
getConstraints: obj => (obj.directives || {}).constraints || {},
isString: obj => obj.type === "String",
isArray: obj => obj.isList,
isInteger: obj => obj.type === "Int",
isBoolean: obj => obj.type === "Boolean",
isDate: obj => obj.type === "Date" || obj.directives.date,
isNumber: obj => obj.type === "Int" || obj.type === "Float",
isObject: obj => obj.type === "Object",
isRequired: obj => !obj.isNullable
};Please note that getConstraints can be used to control where the constraints of the field will be taken from (depending on the type of model/schema or your preference).
Pass overrides to match your model in config as follows:
const schema = buildYup(nameJsonSchema, { ...typeDefConf, log: true });The type definition mappings above are already built-in and available.
To switch the schema type, pass schemaType in config as follows.
const schema = buildYup(nameJsonSchema, { schemaType: "type-def", log: true });Feel free to make PRs to make more common schema models conveniently available!
You can enable logging py passing a log option in the config argument. If set to true, it will by default assign the internal log function to console.log
const schema = buildYup(nameJsonSchema, { log: true });You can also pass a log function in the log option to handle log messages and an err option with a custom error handler function.
See Custom errors in Node for how to design custom errors
class ValidationError extends Error {}
const schema = buildYup(nameJsonSchema, {
log: (name, msg) => console.log(`[${name}] ${msg}`)
err: (msg) => {
console.error(`[${name}] ERROR: ${msg}`
throw new ValidationError(msg)
})
});You can supply a createYupSchemaEntry function as an entry in the config object.
This function will then be used to build each Yup Schema entry in the Yup Schema being built.
Use the Yup Type classes such as types.YupArray to act as building blocks or create your own custom logic as you see fit.
const { YupSchemaEntry, buildYup, types } = require("schema-to-yup");
class CustomYupArray extends types.YupArray {
// ...
}
class CustomYupSchemaEntry extends YupSchemaEntry {
// ...
}
function createYupSchemaEntry(key, value, config) {
const builder = new CustomYupSchemaEntryBuilder(key, value, config);
builder.types.array = config => createYupArray(config);
return builder.toEntry();
}
// use some localized error messages
const messages = i18n.locale(LOCALE);
const yupSchema = buildYup(json, {
createYupSchemaEntry,
messages
});You can use extendYupApi to extend the Yup API with extra validation methods:
const validator = require("validator");
const { extendYupApi } = require("schema-to-yup/validator-bridge");
// by default extends with string format validation methods of validator
// See https://www.npmjs.com/package/validator
extendYupApi({ validator });You can optionally pass in a custom validator and a constraints map of your choice.
You can either extend the default constraints or override them with your own map.
PS: Check out src/validator-bridge for more many options for fine control
const myValidator = new MyValidator();
const constraints = ["creditCard", "currency", { name: "hash", opts: "algo" }];
extendYupApi({ validator: myValidator, override: true, constraints });
const { buildYup } = require("schema-to-yup");
// type def sample schema, using credit-card format validator
const schema = {
name: "BankAccount",
fields: {
accountNumber: {
type: "String",
format: "credit-card"
}
}
};
// opt in to use generic string format validation, via format: true config option
const yupSchema = buildYup(schema, { format: true, schemaType: "type-def" });
// ...do your validation
const valid = await yupSchema.isValid({
accountNumber: "123-4567-1828-2929"
});Now the bridge includes tests and seems to work ;)
You can sublass YupBuilder or any of the internal classes to create your own custom infrastructure to suit your particular needs, extend with extra features etc.
const { YupBuilder } = require("schema-to-yup");
class MyYupBuilder extends YupBuilder {
// ... custom overrides etc
}
const builder = new MyYupBuilder(schema, config);
const { yupSchema } = builder;
// ...You can pass an errMessages object in the optional config object argument with key mappings for your custom validation error messages.
Internally the validator error messages are resolved via an instance of the ErrorMessageHandler calling the valErrMessage method.
notOneOf() {
const {not, notOneOf} = this.value
const $oneOf = notOneOf || (not && (not.enum || not.oneOf))
$oneOf && this
.base
.notOneOf($oneOf, this.valErrMessage('notOneOf'))
return this
}We recommend you subclass the existing ErrorMessageHandler as follow
import { ErrorMessageHandler } from "schema-to-yup";
class MyErrorMessageHandler extends ErrorMessageHandler {
// ...
}
const createErrorMessageHandler = (typeHandler, config = {}) => {
return new MyErrorMessageHandler(typeHandler, config);
};You could f.ex override errMessageFor as follows, using the type
errMessageFor(name) {
return this.propertyErrMessageFor(name) || this.genericErrMessageFor(name)
}
propertyErrMessageFor(name) {
const { errMessages, key } = this;
const errMsg = errMessages[key];
if (!errMsg) return
return errMsg[name]
}
genericErrMessageFor(name) {
const { errMessages, type } = this;
const genricErrMsgMap = errMessages['_generic_'];
const fullName = `${type}.${name}`
return genricErrMsgMap[fullName] || genricErrMsgMap[name];
}Then pass in your factory function in config as follows.
const config = {
createErrorMessageHandler
};You can pass the errMessages as follows. Note that you can define error messages specific to a property such as emailAdr.format and generic messages prefixed with $ such as $email.
Note: This convention might well change in future releases.
let config = {
errMessages: {
emailAdr: {
// note: would also work with email as the key
format: "emailAdr must be a valid email"
},
// generic fallback message for any email format validation
// note: if not present uses yup default validation message
$email: "Email format incorrect"
}
};The key entries can be either a function, taking a value argument or a static string.
Here are some of the defaults that you can override as needed.
export const errValKeys = [
"oneOf",
"enum",
"required",
"notRequired",
"minDate",
"min",
"maxDate",
"max",
"trim",
"lowercase",
"uppercase",
"email",
"url",
"minLength",
"maxLength",
"pattern",
"matches",
"regex",
"integer",
"positive",
"minimum",
"maximum"
];
export const defaults = {
errMessages: (keys = errValKeys) =>
keys.reduce((acc, key) => {
const fn = ({ key, value }) =>
`${key}: invalid for ${value.name || value.title}`;
acc[key] = fn;
return acc;
}, {})
};const { buildYup, types } = require("schema-to-yup");
const { defaults } = types;
const myErrMessages = require("./err-messages");
const valKeys = ["lowercase", "integer"];
// by default Yup built-in validation error messages will be used if not overridden here
const errMessages = {
...defaults.errMessages(valKeys),
myErrMessages
};
const yupSchema = buildYup(json, {
errMessages
});See the number type for the current best practice to add type constraints.
For simple cases: use addConstraint from the superclass YupMixed
required() {
return this.addConstraint("required");
}For types with several of these, we should map through a list or map to add them all.
strict() {
return this.addValueConstraint("strict");
}
required() {
return this.addConstraint("required");
}
notRequired() {
return this.addConstraint("notRequired");
}Can be rewritten to use conventions, iterating a map:
addMappedConstraints() {
Object.keys(this.constraintsMap).map(key => {
const list = constraintsMap[key];
const fnName = key === 'value' ? 'addValueConstraint' : 'addConstraint'
list.map(this.[fnName]);
});
}
get constraintsMap() {
return {
simple: ["required", "notRequired", "nullable"],
value: ["default", "strict"]
};
}For more complex contraints that:
- have multiple valid constraint names
- require validation
- optional transformation
You can create a separate Constraint subclass, to offload and handle it all separately.
Here is a sample RangeConstraint used by number.
class RangeConstraint extends NumericConstraint {
constructor(typer) {
super(typer);
}
get $map() {
return {
moreThan: ["exclusiveMinimum", "moreThan"],
lessThan: ["exclusiveMaximum", "lessThan"],
max: ["maximum", "max"],
min: ["minimum", "min"]
};
}
}Instead of wrapping a Constraint you can call it directly with a map
// this would be an instance such as YupNumber
// map equivalent to $map in the RangeConstraint
range() {
return createNumericConstraint(this, map);
}For the core type constraint class (such as YupNumber) you should now be able to simplify it to:
get enabled() {
return ["range", "posNeg", "integer"];
}
convert() {
this.enabled.map(name => this.processConstraint(name));
super.convert();
return this;
}The following constraint classes are available for use:
NumericConstraintStringConstraintRegExpConstraintDateConstraint
Currently only YupNumber has been (partly) refactored to take advantage of this new infrastructure. Please help refactor the rest!
YupNumber also has the most unit test coverage, used to test the current infrastructure!
- JSON schema to Elastic Search mapping
- JSON Schema to GraphQL types with decorators/directives
- JSON Schema to Mongoose schema
- JSON Schema to MobX State Tree types
- Convert JSON schema to mongoose 5 schema
The library JSON Schema model builder is a powerful toolset to build a framework to create any kind of output model from a JSON schema.
If you enjoy this declarative/generator approach, try it out!
Uses jest for unit testing.
- Have unit tests that cover most of the constraints supported.
- Could use some refactoring using the latest infrastructure (see
NumericConstraint) - Please help add more test coverage and help refactor to make this lib even more awesome :)
Current development is taking place on refactoring branch.
On his branch:
- all the code has been converted to TypeScript
- constraint classes for String, Numeric, RegExp etc.
- Validator building has been extracted so you can add support for any Validator, such as Forg
- more...
If you would like to further improved this library or add support for more validators than Yup, please help on this branch. Cheers!
Please feel free to come with ideas and suggestions on how to further improve this library.
2018 Kristian Mandrup (CTO@Tecla5)
MIT