packages/node_modules/pouchdb-find/src/validateSelector.js

// throws if the user is using the wrong query field value type
function checkFieldValueType(name, value, isHttp) {
	var message = '';
	var received = value;
	var addReceived = true;
	if ([ '$in', '$nin', '$or', '$and', '$mod', '$nor', '$all' ].indexOf(name) !== -1) {
		if (!Array.isArray(value)) {
			message = 'Query operator ' + name + ' must be an array.';

		}
	}

	if ([ '$not', '$elemMatch', '$allMatch' ].indexOf(name) !== -1) {
		if (!(!Array.isArray(value) && typeof value === 'object' && value !== null)) {
			message = 'Query operator ' + name + ' must be an object.';
		}
	}

	if (name === '$mod' && Array.isArray(value)) {
		if (value.length !== 2) {
			message = 'Query operator $mod must be in the format [divisor, remainder], ' +
				'where divisor and remainder are both integers.';
		} else {
			var divisor = value[0];
			var mod = value[1];
			if (divisor === 0) {
				message = 'Query operator $mod\'s divisor cannot be 0, cannot divide by zero.';
				addReceived = false;
			}
			if (typeof divisor !== 'number' || parseInt(divisor, 10) !== divisor) {
				message = 'Query operator $mod\'s divisor is not an integer.';
				received = divisor;
			}
			if (parseInt(mod, 10) !== mod) {
				message = 'Query operator $mod\'s remainder is not an integer.';
				received = mod;
			}
		}
	}
	if (name === '$exists') {
		if (typeof value !== 'boolean') {
			message = 'Query operator $exists must be a boolean.';
		}
	}

	if (name === '$type') {
		var allowed = [ 'null', 'boolean', 'number', 'string', 'array', 'object' ];
		var allowedStr = '"' + allowed.slice(0, allowed.length - 1).join('", "') + '", or "' + allowed[allowed.length - 1] + '"';
		if (typeof value !== 'string') {
			message = 'Query operator $type must be a string. Supported values: ' + allowedStr + '.';
		} else if (allowed.indexOf(value) == -1) {
			message = 'Query operator $type must be a string. Supported values: ' + allowedStr + '.';
		}
	}

	if (name === '$size') {
		if (parseInt(value, 10) !== value) {
			message = 'Query operator $size must be a integer.';
		}
	}

	if (name === '$regex') {
		if (typeof value !== 'string') {
			console.log("here", isHttp);
			if (isHttp) {
				message = 'Query operator $regex must be a string.';
			} else if (!(value instanceof RegExp)) {
				message = 'Query operator $regex must be a string or an instance ' +
					'of a javascript regular expression.';
			}
		}
	}

	if (message) {
		if (addReceived) {

			var type = received === null
			? ' '
			: Array.isArray(received)
			? ' array'
			: ' ' + typeof received;
			var receivedStr = typeof received === 'object' && received !== null
			?  JSON.stringify(received, null, '\t')
			: received;

			message += ' Received' + type + ': ' + receivedStr;
		}
		throw new Error(message);
	}
}


var requireValidation = [ '$all', '$allMatch', '$and', '$elemMatch', '$exists', '$in', '$mod', '$nin', '$nor', '$not', '$or', '$regex', '$size', '$type' ];

var arrayTypeComparisonOperators = [ '$in', '$nin', '$mod', '$all'];

var equalityOperators = [ '$eq', '$gt', '$gte', '$lt', '$lte' ];

// recursively walks down the a query selector validating any operators
function validateSelector(input, isHttp) {
	if (Array.isArray(input)) {
		for (var entry of input) {
			if (typeof entry === 'object' && value !== null) {
				validateSelector(entry, isHttp);
			}
		}
	} else {
		var fields = Object.keys(input);

		for (var i = 0; i < fields.length; i++) {
			var key = fields[i];
			var value = input[key];

			if (requireValidation.indexOf(key) !== -1) {
				checkFieldValueType(key, value, isHttp);
			}
			if (equalityOperators.indexOf(key) !== -1) {
				// skip, explicit comparison operators can be anything
				continue;
			}
			if (arrayTypeComparisonOperators.indexOf(key) !== -1) {
				// skip, their values are already valid
				continue;
			}
			if (typeof value === 'object' && value !== null) {
				validateSelector(value, isHttp);
			}
		}
	}
}

export default validateSelector;