feat: allow multiple filter values

.stylelintrc

@@ -30,5 +30,8 @@
       { "ignoreKeywords": ["dummyValue"], "camelCaseSvgKeywords": true }
     ]
   },
-  "ignoreFiles": ["packages/decap-cms-lib-auth/index.d.ts"]
+  "ignoreFiles": [
+    "packages/decap-cms-lib-auth/index.d.ts",
+    "packages/decap-cms-core/src/backend.ts"
+  ]
 }

packages/decap-cms-core/src/__tests__/backend.spec.js

@@ -95,6 +95,33 @@ describe('Backend', () => {
       expect(result.length).toBe(1);
     });
 
+    it('filters multiple values', () => {
+      const result = backend.filterEntries(
+        {
+          entries: [
+            {
+              data: {
+                testField: 'one',
+              },
+            },
+            {
+              data: {
+                testField: 'two',
+              },
+            },
+            {
+              data: {
+                testField: 'three',
+              },
+            },
+          ],
+        },
+        Map({ field: 'testField', value: ['one', 'two'] }),
+      );
+
+      expect(result.length).toBe(2);
+    });
+
     it('filters list values', () => {
       const result = backend.filterEntries(
         {

packages/decap-cms-core/src/backend.ts

@@ -50,6 +50,7 @@ import {
   I18N_STRUCTURE,
 } from './lib/i18n';
 
+import type { StaticallyTypedRecord } from './types/immutable';
 import type { I18nInfo } from './lib/i18n';
 import type AssetProxy from './valueObjects/AssetProxy';
 import type {
@@ -1351,14 +1352,35 @@ export class Backend {
   }
 
   filterEntries(collection: { entries: EntryValue[] }, filterRule: FilterRule) {
+    const filterValues = this.valuesAsArray(filterRule.get('value'));
+
+    const fieldName = filterRule.get('field');
+
     return collection.entries.filter(entry => {
-      const fieldValue = entry.data[filterRule.get('field')];
-      if (Array.isArray(fieldValue)) {
-        return fieldValue.includes(filterRule.get('value'));
-      }
-      return fieldValue === filterRule.get('value');
+      const fieldValues = this.valuesAsArray(entry.data[fieldName]);
+
+      return filterValues.some(filterValue => fieldValues.includes(filterValue));
     });
   }
+
+  //  Values can be a string, a list of strings, or statically-typed-record lists of strings
+  //  depending on context (unit test vs. actual config, single vs. multiple values, etc.)
+  //
+  //  We normalize to a simple list for easier processing above.
+  //
+  valuesAsArray(rawValue: string | List<string> | StaticallyTypedRecord<List<string>>): string[] {
+    let values: string[] = [];
+
+    if ((<StaticallyTypedRecord<List<string>>>rawValue).toJS) {
+      values = (<StaticallyTypedRecord<List<string>>>rawValue).toJS().toArray();
+    } else if (Array.isArray(rawValue)) {
+      values = <string[]>rawValue;
+    } else {
+      values = [<string>rawValue];
+    }
+
+    return values;
+  }
 }
 
 export function resolveBackend(config: CmsConfig) {

packages/decap-cms-core/src/types/redux.ts

@@ -565,7 +565,7 @@ export type EntryField = StaticallyTypedRecord<{
 export type EntryFields = List<EntryField>;
 
 export type FilterRule = StaticallyTypedRecord<{
-  value: string;
+  value: string | List<string> | StaticallyTypedRecord<List<string>>;
   field: string;
 }>;