fix: where-filter null handling (#457)

src/builtin/filters/array.ts

@@ -3,6 +3,7 @@ import { toArray } from '../../util/collection'
 import { isTruthy } from '../../render/boolean'
 import { FilterImpl } from '../../template/filter/filter-impl'
 import { Scope } from '../../context/scope'
+import { isComparable } from '../../drop/comparable'
 
 export const join = (v: any[], arg: string) => v.join(arg === undefined ? ' ' : arg)
 export const last = (v: any) => isArray(v) ? arrayLast(v) : ''
@@ -40,7 +41,9 @@ export function slice<T> (v: T[], begin: number, length = 1): T[] {
 export function where<T extends object> (this: FilterImpl, arr: T[], property: string, expected?: any): T[] {
   return toArray(arr).filter(obj => {
     const value = this.context.getFromScope(obj, String(property).split('.'))
-    return expected === undefined ? isTruthy(value, this.context) : value === expected
+    if (expected === undefined) return isTruthy(value, this.context)
+    if (isComparable(expected)) return expected.equals(value)
+    return value === expected
   })
 }
 

test/integration/builtin/filters/array.ts

@@ -183,6 +183,18 @@ describe('filters/array', function () {
         - Boring sneakers
         `)
     })
+    it('should support filter by null property', function () {
+      return test(`{% assign untyped_products = products | where: "type", null %}
+        Untyped products:
+        {% for product in untyped_products -%}
+        - {{ product.title }}
+        {% endfor %}`, { products }, `
+        Untyped products:
+        - Coffee mug
+        - Limited edition sneakers
+        - Boring sneakers
+        `)
+    })
     it('should support nested property', async function () {
       const authors = [
         { name: 'Alice', books: { year: 2019 } },