BitSchema

BitSchema covers most validation and transformation requirements and also supports custom parsing for special cases. Schema objects created with schema() have a schema property as well as parse, parsePartial, and parseProperty methods. Each of these methods will always return either an object containing data or invalid.

Example:

import { schema } from "bitschema";

export const Book = schema({
  title: "string|min:3",
  pages: "number|optional",
});

Now this schema can be imported and used for data transformation and validation:

import { Book } from "/schema/Book.js";

const myBook = { title: "It", pages: 350 }
const { data, invalid } = Book.parse(ctx.payload);

Handling the returned data or invalid object

BitSchema will always return an object containing either a data or invalid object.

If validation passes, a data object will be returned containing the parsed data which includes only properties defined in the schema and transformed according to its data type. For example, if pages is submitted as an input field in a web form, this arrives at the server as a string type (because all values submitted through web forms are strings). But because the specified type for pages is "number", the returned value in data.pages will be a number type ready for insertion to the database.

If validation fails, the invalid object will contain the validation errors keyed by the field name. For example if "abc" was submitted through a web form for pages, the return value for invalid.pages would be "Pages must be a number".

Validating a partial object

In some cases, you may want to validate only a partial object. For example, when updating a record, you may want to validate only the fields that were submitted. In this case, use the parsePartial() method instead of parse() like this:

const { data, invalid } = Book.parsePartial(ctx.payload);

Note that only submitted fields will be validated and returned in the data object. Any fields not submitted will be ignored regardless whether specified as optional or required (default).

Validating a single form field

You may also validate a single form field by passing in the property name and value to parseProperty like this:

const { invalid, data } = Book.parseProperty("title", "Dune");

Schema types and options

A schema item must start with a data type followed by zero or more options. All types support optional, default, label, and custom functions. optional makes the property optional.default sets the default value (effectively making it also optional). label allows you to specify a custom label for the field name used in invalid message values and uses the key set to titlecase by default. For example, if the field name is title, the default label will be "Title". The label option allows you to override this. For example, label:Book Title will result in "Book Title" being used in invalid messages instead of "Title".

Available types and their respective options include:

"string"

Returns the parsed data property as a string or returns an invalid object.

• min:<number>: Minimum length
• max:<number>: Maximum length
• startsWith:<string>: Must start with specified string
• endsWith:<string>: Must end with specified string
• includes:<string>: Must include specified string
• email: Must match valid email format
• url: Must match valid url format
• id: Must match valid MongoDB ObjectId format
• optional: Field is optional
• default: Set a default string value
• label: A custom label for invalid messages
• <string>: A custom function

"number"

Returns the parsed data property as a number or returns an invalid object.

• min:<number>: Minimum value
• max:<number>: Maximum value
• integer: Must be an integer
• optional: Field is optional
• default: Set a default number value
• label: A custom label for invalid messages
• <string>: A custom function

"boolean"

Returns the parsed data property as a number or returns an invalid object. The following values are coerced to true: true, "true", "1", 1. The following values are coerced to false: false, "false", "0", 0.

• optional: Field is optional
• default: Set a default boolean value
• label: A custom label for invalid messages
• <string>: A custom function

object

Returns the object as is or returns an invalid object. Note that this type is useful for validating objects of unknown shape. If you know the shape of the object, it's better to use a nested object schema.

• optional: Field is optional
• default is not supported for this type
• label: A custom label for invalid messages
• <string>: A custom function

date

Returns the object as a date or returns an invalid object.

• optional: Field is optional
• default is not supported for this type
• label: A custom label for invalid messages
• <string>: A custom function

any

Returns the value as is. Any value is accepted.

• optional: Field is optional
• default is not supported for this type
• label: A custom label for invalid messages
• <string>: A custom function

[string], [number], [boolean], [object], [date], [any]

These are the array equivalents of the above types. For example, [string] will return an array of strings or an invalid object.

Custom functions

Any custom function can be used as a schema option in conjunction with a standard type. To do this, create a function which receives the value and returns an object containing either data or invalid, then pass the function as a second argument to the schema() function. Then reference the function name as a schema option like this:

const { data, invalid } = schema({
  pages: "number|isEven",
}, isEven);

function isEven(value) {
  return value % 2 === 0 
    ? { data: value } 
    : { invalid: "must be an even number" };
}

In line 2, we use the isEven custom function as a schema option. Then in line 3, pass in the isEven function defined in line 5 which receives the value and returns either data or invalid depending on whether the value is divisible by 2. Note that the string assigned to invalid will be prepended with the label value, e.g., "Pages must be an even number".