scem v3.0.1

Scem

Scem is a small js package to validate object by using schema

How to create schema

Here how to create a schema

const schema = new Schema({ foo: { type: "string", required: true } });

How to validate an object

Now that your schema is created it would be nice to use it to validate an object. Here is how you can do it

const isValid = schema.validate({ foo: "hello world" });

You can also activate the errors options to return get back an error array on each property (by default this options is set to false)

const { valid, errors } = schema.validate({ foo: "hello world" }, { errors: true }) // will return {valid: true, errors: [] }

If this option is activated and there is no errors the errors property will be an empty array but if there is an error on a property for example we expect a string, but we got a number it will send back an array like this :

const errors = [{
  property: "foo",
  error: "Invalid type, type must be string"
}]

Conditions

type

With this condition you can specify the type of the value

const schema = new Schema({ foo: { type: "string" } })

the possible values are :

• string
• number
• boolean
• array

required

This condition can be used to specify if the property is needed or not if you omit it, it will be equal to false

const schema = new Schema({ foo: { required: true } })

the possible values are :

• true
• false

min

This condition can be used to specify a min value for a number

const schema = new Schema({ foo: { min: 0 } })

When validating a number this condition will be valid if the number is equal or superior to min

const valid = schema.validate({ foo: 0 }) // valid = true

max

This condition can be used to specify a max value for a number

const schema = new Schema({ foo: { max: 1 } })

When validating a number this condition will be valid if the number is equal or less to max

const valid = schema.validate({ foo: 1 }) // valid = true

minLength

this condition can be used to specify a minLength for a string or an array

const schema = new Schema({ foo: { minLength: 1 } })

When validating this condition will be valid if the length is equal or superior to minLength

const valid = schema.validate({ foo: "t" }) // valid = true

maxLength

this condition can be used to specify a maxLength for a string or an array

const schema = new Schema({ foo: { maxLength: 1 } })

When validating this condition will be valid if the length is equal or less to maxLength

const valid = schema.validate({ foo: "t" }) // valid = true

regex

this condition can be used to check if a string match a regex. If the string doesn't match it will return false

const schema = new Schema({ foo: { regex: /\d/gi } });

expected

this condition can be used to specify an expected value for a property

const schema = new Schema({ foo: { expected: 1 } });

/!\ this condition works only for primitive types : string, number, boolean

validator

This condition allow you to define your own custom validator. To create a custom validator you have to create a function that take one parameter and throw an error on conditions

/!\ One important thing to note is that the validator is always the last condition to be checked

const isEven = (value: any): boolean => {
  if (value % 2 !== 0) {
    throw new Error("Value is not even");
  }
}

Once your validator is created you can use it like that

const schema = new Schema({ foo: { validator: isEven } });