FlexSchema is a highly flexible and dynamic schema library.

Instability Please be warned that this is library is still quite unstable and lacks enough tests. If you do find bugs, please file issues or even better submit PR fixes.

yarn add flexschema or npm install flexschema

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import {FlexSchema, SchemaSnapshot, type, Error, Loader, Path, SchemaStore, ProcessorStore, Constants} from 'flexschema';

Let's say we want to setup a schema for a user object.

First, we start simple:

let userSchema = {
	type: 'object',
	shape: {
		profile: {
			type: 'object',
			shape: {
				firstName: {
					type: 'string',
					min: 1,
					max: 100
				}
			}
		}
	}
};

We can do mainly two things with the above schema.

FlexSchema.register({
	namespace: 'example',
	name: 'user',
	schema: userSchema
});

let schema = FlexSchema.init({
	namespace: 'example',
	name: 'user'
});

let context = schema.process({
	data
});

console.log(context.getData());

This outputs:

{
	"profile": {
		"firstName": ""
	}
}

The schema processor is used to generate missing fields. The generated data may not pass validation rules but it provides a "skeleton" data structure useful for redux/react applications.

context = schema.validate({
	data
});

console.log(context.getErrors());

{
	"type": "type",
	"message": "Value must be of type \"object\".",
	"details": {
		"context": {
			"currentPath": {
				"path": [
					"profile"
				]
			}
		}
	}
}

All fields can be functions which are evaluated at the processing/validation step.

For instance, say we have a year of birth field that must not allow years beyond the current year:

userSchema = {
	type: 'object',
	shape: {
		profile: {
			type: 'object',
			shape: {
				firstName: {
					type: 'string',
					min: 1,
					max: 100
				},
				yearOfBirth: {
					type: 'number',
					min: 1850,
					max: () => (new Date()).getFullYear() // At the time of writing, it's 2017
				}
			}
		}
	}
};

Upon validation, you get:

{
	"type": "max",
	"message": "Value must be less than or equal to 2017.",
	"details": {
		"context": {
			"currentPath": {
				"path": [
					"profile",
					"yearOfBirth"
				]
			}
		}
	}
}

Dynamic fields can be async functions (useful when the value comes from I/O sources).

FlexSchema is a very powerful schema library and boasts a long list of features. This example only covers some of the basic features. For a more in-depth understanding of FlexSchema, check out the documentation.