validate_doc_update.js

function(newDoc, oldDoc, userCtx) {

    // Don't validate documents being deleted
    if (newDoc._deleted) {
        return;
    }

    // We require a schema to do validation
    if (!newDoc.schema) {
        throw({forbidden : 'The document schema is missing.'});
    }

    // ...and that schema must exist in the couchapp
    if (!this.schema.hasOwnProperty(newDoc.schema)) {
        throw({forbidden : 'There is no schema for: ' + newDoc.schema});
    }

    // Comment this out if you are throwing an admin party.
    // This check simply enforces that the author is who they claim to be
    //if (userCtx.name !== newDoc.author) {
    //    throw({forbidden: "Author must be the current user"});
    //}

    var
        JSV = require("lib/jsv").JSV,
        env = JSV.createEnvironment('json-schema-draft-03'),
        report = env.validate(newDoc, this.schema[newDoc.schema]),
        property;

    if (report.errors.length) {

        // Can only throw one error at a time (without stringifying)
        // See issue: COUCHDB-1635
        // https://issues.apache.org/jira/browse/COUCHDB-1635
        property = report.errors[0].uri.split('/')[1];
        
        if (property) {
            error = report.errors[0].message + " : " + property;
        } else {
            error = report.errors[0].message;
        }

        throw({forbidden: error});
    }
}