adding

src/filter.js

@@ -72,26 +72,24 @@ class Filter {
 	_in(value, key, result) {
 		let isValid = false
 
-		if (!result[key]) {
-			isValid = false
-		}
-
-		if (Array.isArray(value)) {
-			let found = false
-
-			// run through array
-			value.forEach((v, index) => {
-				if (result[key].indexOf(v) !== -1) {
-					found = true
+		if (result[key]) {
+			if (Array.isArray(value)) {
+				let found = false
+
+				// run through array
+				value.forEach((v, index) => {
+					if (result[key].indexOf(v) !== -1) {
+						found = true
+					}
+				})
+
+				if (found) {
+					isValid = true
+				}
+			} else {
+				if (result[key].indexOf(value) !== -1) {
+					isValid = true
 				}
-			})
-
-			if (found) {
-				isValid = true
-			}
-		} else {
-			if (result[key].indexOf(value) !== -1) {
-				isValid = true
 			}
 		}
 

test/filter.js

@@ -54,6 +54,21 @@ describe('Filter', function () {
 		assert.equal(filter.validate(data), true)
 	})
 
+	it('_in single, missing tags', function() {
+
+		const filter = new Filter({
+			tags: {
+				_in: 'monday'
+			}
+		})
+
+		const data = {
+			name: 'monday'
+		}
+
+		assert.equal(filter.validate(data), false)
+	})
+
 	it('_in array', function() {
 
 		const filter = new Filter({