spleen-mongodb

The spleen module provides high-level abstractions for dynamic filters. This module will convert a spleen Filter into a MongoDB Query Filter Document object.

Contents

• Usage
• API
• Security

Usage

Add spleen-mongodb to your package.json file's dependencies:

$ npm install spleen-mongodb -S

Then use it in your code:

const spleen = require('spleen');
const splongo = require('spleen-mongodb');

const filter = spleen.parse('/foo/bar eq 42 and /baz in [1,2,3] or /qux gt 0');
const result = splongo.convert(filter);

console.log(result.value);
// {
//   "$or": [
//     {
//       "$and": [
//         { "foo.bar": 42 },
//         { "baz": { "$in": [1, 2, 3,] } }
//       ]
//     },
//     { "qux": { "$gt": 0 } }
//   ]
// }

API

The spleen-mongodb module provides the following interface.

splongo.convert(filter [, strategy])

Converts an instance of spleen's Filter class into an MongoDB Query Filter Document object.

Parameters

• filter: (required) the instance of Filter to convert.

• strategy: (optional) an instance of Strategy.

Returns

An object with the following keys:

• fields: an array of RFC 6901 JSON pointer values, representing the fields referenced by the converted Fitler.

• value: the MongoDB Query Filter Document.

splongo.errors.ConvertError

A general error thrown when spleen-mongodb is unable to convert a given Filter instance into a Query Filter Document object. This should generally never happen, and is here as a safeguard in the event a Filter instance is corrupted.

splongo.errors.DeniedFieldError

An error thrown when a field is encountered that has been explicitly black-listed by the deny option.

splongo.errors.InvalidTargetError

An error thrown if a target is encountered with an invalid format. For example, if a segment of the path contains reserved characters.

splongo.errors.UnallowedFieldError

An error thrown when a field is encountered that has not been white-listed by the allow option.

splongo.errors.RequiredFieldError

An error thrown when a Filter instance is passed to convert() missing a required field.

splongo.Strategy

A class that represents a conversion strategy. Instances are meant to be cached in memory to prevent having to recompute this information with every call to convert().

Strategy.prototype.constructor([options])

Create a new instance of Strategy.

• options: (optional) an object that provides conversion options. This object can have the keys:

  • allow: (optional) an array of RFC 6901 JSON pointer strings that are allowed to be in a Filter's list of targets. Any targets in a Filter instance not found in the allow or require lists will result in an error being thrown. This list functions as a white list, and can only be present if deny is absent. An empty array is the logical equivalent of the allow key being absent.

  • deny: (optional) an array of RFC 6901 JSON pointer strings that are not allowed to be in a Filter's list of targets. Any targets in a Filter instance found in this list will result in an error being thrown. This list functions as a black list, and can only be present if allow is absent.

  • require: (optional) object that specifies required field target behavior. This object can have the following keys:

    • fields: (optional) an array of RFC 6901 JSON pointer strings that are required to be in a Filter's list of targets (Filter.prototype.targets). If a required target is missing, an error is thrown. If this key is omitted or empty, there are assumed to be no required fields.

    • which: (optional) a string specifying which fields are required to be in a given Filter. This can be either any or all. If omitted, this value defaults to any.

Security

The combination of spleen and spleen-mongodb add a number of layers of protection to prevent NoSQL-injection attacks vulnerabilities. Either spleen will refuse to parse a given filter, or spleen-mongodb will throw an error if reserved MongoDB tokens are encountered.

That said, there are a couple of other things to consider:

1. It is advised that implementers make use of the Strategy class' allow/deny and require functionality. The idea is to prevent a DoS attack vector by ensuring expensive queries against un-indexed fields cannot be executed.

2. The spleen and spleen-mongodb libraries do not, and cannot, ensure queries are not executed against data to which a user lacks sufficient permission. When required, implementers should append static authorization checks to all queries taken as input.