validate-with-xmllint

Wrapper for xmllint. Easy validation of XML. XML Schemas and DTDs supported. Zero dependencies.

Features

Validate schemaless XML file 👉 function validateXML(input: string | Buffer): Promise<void>
Validate with DTDs 👉 function validateXMLWithDTD(input: string | Buffer): Promise<void>
Validate with XML Schemas (XSD) 👉 function validateXMLWithXSD(input: string | Buffer, xsdfile: string | Buffer): Promise<void>
Written in TypeScript
Tests with good coverage included
Zero NPM dependencies
Availability of xmllint is verified during installation time
No network connections used during validations

Usage

Importing functions

const {
  validateXML,
  validateXMLWithDTD,
  validateXMLWithXSD
} = require("validate-with-xmllint");

Demos of passing validations

All the examples below return promises which will eventually resolve.

validateXML("<hello>world!</hello>");
validateXML("<tiny/>");

/**
 * All referenced DTD's must be available locally as `xmllint`
 * is invoked with `--nonet` which prevents network connections
 **/
validateXMLWithDTD(
  `<?xml version="1.0" encoding="utf-8"?>
    <!DOCTYPE root SYSTEM "./test/dtds/valid-dtd.dtd">
    <root>
        <body/>
        <body/>
    </root>`
);

/**
 * Path to XSD Schema file must be provided with the document
 **/
validateXMLWithXSD(
  `<?xml version="1.0"?>
    <root>
        <text>
        DEMO
        </text>
        <body>
            <name>foo</name>
        </body>
    </root>`,
  "./test/xsds/valid-xsd.xsd"
);

Demos of failing validations

All the examples below return promises which will eventually reject with the output from xmllint.

validateXML("<open_tag_only>");
validateXML("garbage");

validateXMLWithDTD(
  `<?xml version="1.0" encoding="utf-8"?>
    <!DOCTYPE root SYSTEM "./test/dtds/valid-dtd.dtd">
    <this>
      Not allowed by the dtd!
    </this>`
);

validateXMLWithXSD(
  `<?xml version="1.0"?>
    <root>
        <something_unexpected_here/>
    </root>`,
  "./test/xsds/valid-xsd.xsd"
);

See more demos within the tests.

FAQ

Package install fails with error "Failed at the validate-with-xmllint@... postinstall script."

The validate-with-xmllint is a wrapper for program xmllint. A postinstall script fails if it is not available. See next section for further info.

How to install `xmllint`?

You might already have it. Execute xmllint --version and see what it prints out.

On Debian distros look up libxml2-utils, on RedHat libxml2. A recent version of xmllint should be bundled by default on MacOS.

This package runs a postinstall script to verify that you have xmllint available.

How to see the actual errors in my XML?

The promise is rejected with the error output from xmllint. The error contains all the available details. Expect to see something like this:

Error: xmllint exited with code 3 when executed with xmllint --schema /Users/aautio/foobar/validate-with-xmllint/test/xsds/valid-xsd.xsd --noout --nonet -:
-:2: element root: Schemas validity error : Element 'root': Missing child element(s). Expected is ( body ).
- fails to validate

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