relative date field formatter (#13921)

* add relative date field formatter

* add unit test for relative_date field formatter

src/core_plugins/kibana/common/field_formats/types/__tests__/relative_date.js

@@ -0,0 +1,26 @@
+import expect from 'expect.js';
+import moment from 'moment-timezone';
+import { RelativeDateFormat } from '../relative_date';
+
+describe('Relative Date Format', function () {
+  let convert;
+
+  beforeEach(function () {
+    const relativeDate = new RelativeDateFormat({});
+    convert = relativeDate.convert.bind(relativeDate);
+  });
+
+  it('decoding an undefined or null date should return a "-"', function () {
+    expect(convert(null)).to.be('-');
+    expect(convert(undefined)).to.be('-');
+  });
+
+  it('decoding invalid date should echo invalid value', function () {
+    expect(convert('not a valid date')).to.be('not a valid date');
+  });
+
+  it('should parse date values', function () {
+    const val = '2017-08-13T20:24:09.904Z';
+    expect(convert(val)).to.be(moment(val).fromNow());
+  });
+});

src/core_plugins/kibana/common/field_formats/types/relative_date.js

@@ -0,0 +1,25 @@
+import moment from 'moment';
+import { FieldFormat } from '../../../../../ui/field_formats/field_format';
+
+export class RelativeDateFormat extends FieldFormat {
+  constructor(params) {
+    super(params);
+  }
+
+  _convert(val) {
+    if (val === null || val === undefined) {
+      return '-';
+    }
+
+    const date = moment(val);
+    if (date.isValid()) {
+      return date.fromNow();
+    } else {
+      return val;
+    }
+  }
+
+  static id = 'relative_date';
+  static title = 'Relative Date';
+  static fieldType = 'date';
+}

src/core_plugins/kibana/public/field_formats/__tests__/_conformance.js

@@ -20,7 +20,8 @@ const formatIds = [
   'url',
   '_source',
   'truncate',
-  'boolean'
+  'boolean',
+  'relative_date'
 ];
 
 // eslint-disable-next-line kibana-custom/no-default-export

src/core_plugins/kibana/public/field_formats/register.js

@@ -2,6 +2,7 @@ import { RegistryFieldFormatsProvider } from 'ui/registry/field_formats';
 import { UrlFormat } from '../../common/field_formats/types/url';
 import { BytesFormat } from '../../common/field_formats/types/bytes';
 import { DateFormat } from '../../common/field_formats/types/date';
+import { RelativeDateFormat } from '../../common/field_formats/types/relative_date';
 import { DurationFormat } from '../../common/field_formats/types/duration';
 import { IpFormat } from '../../common/field_formats/types/ip';
 import { NumberFormat } from '../../common/field_formats/types/number';
@@ -15,6 +16,7 @@ import { BoolFormat } from '../../common/field_formats/types/boolean';
 RegistryFieldFormatsProvider.register(() => UrlFormat);
 RegistryFieldFormatsProvider.register(() => BytesFormat);
 RegistryFieldFormatsProvider.register(() => DateFormat);
+RegistryFieldFormatsProvider.register(() => RelativeDateFormat);
 RegistryFieldFormatsProvider.register(() => DurationFormat);
 RegistryFieldFormatsProvider.register(() => IpFormat);
 RegistryFieldFormatsProvider.register(() => NumberFormat);