Date and time formatting

In this guide we will learn how date a time formatting can be customized within SDK’s components.

SDK components displaying date & time

The following components provided by the SDK display date time:

• ChannelPreviewStatus - Component showing last message date and time in ChannelList.
• ImageGalleryHeader - Component showing the header in the ImageGallery.
• InlineDateSeparator - Component separating groups of messages in MessageList.
• MessageEditedTimestamp - Component showing edited message time when clicked on an edited message.
• MessageSystem - Component showing system message.
• MessageTimestamp - Component showing message timestamp.
• StickyHeader - Component showing sticky header on the top of the MessageList/Channel.

Format Customization

The date time format can be customized by providing date format through the i18n JSON.

Date & time formatting with i18n service

Formatting via i18n service allows for SDK wide configuration. The configuration is stored with other translations in JSON files. Formatting with i18n service has the following advantages:

• It is centralized.
• It takes into consideration the locale out of the box.
• Allows for high granularity - formatting per string, not component (opposed to props approach).
• Allows for high re-usability - apply the same configuration in multiple places via the same translation key.
• Allows for custom formatting logic.

The default date time formatting configuration is stored in the JSON translation files. The default translation keys are namespaced with prefix timestamp/ followed by the component name. For example, the message date formatting can be targeted via timestamp/MessageTimestamp, because the underlying component is called MessageTimestamp.

We can apply custom configuration in all the translation JSON files. It could look similar to the following example key-value pair.

"timestamp/SystemMessage": "{{ timestamp | timestampFormatter(format: YYYY) }}",

Besides overriding the formatting parameters above, we can customize the translation key via timestampTranslationKey prop. All the above components (ChannelPreviewStatus, ImageGalleryHeader, InlineDateSeparator, MessageEditedTimestamp, MessageSystem, MessageTimestamp, StickyHeader) accept this prop.

import {
  MessageTimestampProps,
  MessageTimestamp,
} from "stream-chat-react-native";

const CustomMessageTimestamp = (props: MessageTimestampProps) => (
  <MessageTimestamp
    {...props}
    timestampTranslationKey="customTimestampTranslationKey"
  />
);

Understanding the formatting syntax

Once the default prop values are nullified, we override the default formatting rules in the JSON translation value. We can take a look at an example:

"timestamp/MessageSystem": "{{ timestamp | timestampFormatter(calendar: true) }}",

or with custom calendar formats:

"timestamp/MessageSystem": "{{ timestamp | timestampFormatter(calendar: true; calendarFormats: {\"lastDay: \"[gestern um] LT\", \"lastWeek\": \"[letzten] dddd [um] LT\", \"nextDay\": \"[morgen um] LT\", \"nextWeek\": \"dddd [um] LT\", \"sameDay\": \"[heute um] LT\", \"sameElse\": \"L\"}) }}",

or with custom format:

"timestamp/MessageTimestamp": "{{ timestamp | timestampFormatter(format: LT) }}",

Let’s dissect the example:

• The curly brackets ({{, }}) indicate the place where a value will be interpolated (inserted) into the string.
• Variable timestamp is the name of variable which value will be inserted into the string.
• The | character is a pipe that separates the variable from the formatting function.
• The timestampFormatter is the name of the formatting function that is used to convert the timestamp value into desired format
• The timestampFormatter can be passed the same parameters as the React components (calendar, calendarFormats, format) as if the function was called with these values.

Params:

• calendar - This is a Boolean field to decide if the date format should be in calendar format or not. The default value is false.
• calendarFormats - This is an object that contains the formats for the calendar. The default value is { sameDay: 'LT', nextDay: 'LT', nextWeek: 'dddd', lastDay: 'dddd', lastWeek: 'dddd', sameElse: 'L' }.
• format - This is a string that contains the format of the date.

If calendar formatting is enabled, the dates are formatted with time-relative words ("yesterday at ...", "last ..."). The calendar strings can be further customized with calendarFormats object. The calendarFormats object has to cover all the formatting cases as shows the example below:

{
  lastDay: '[gestern um] LT',
  lastWeek: '[letzten] dddd [um] LT',
  nextDay: '[morgen um] LT',
  nextWeek: 'dddd [um] LT',
  sameDay: '[heute um] LT',
  sameElse: 'L',
}

If calendar formatting is enabled, the format prop would be ignored. So to apply the format string, the calendar has to be disabled.

Custom date time formatter functions

Besides overriding the configuration parameters, we can override the default timestampFormatter function by providing custom Streami18n instance:

import { Chat, Streami18n } from "stream-chat-react-native";

const chatClient = "Your Chat client here";

const i18n = new Streami18n({
  formatters: {
    timestampFormatter: () => (val: string | Date) => {
      return new Date(val).getTime() + "";
    },
  },
});

export const ChatApp = ({ apiKey, userId, userToken }) => {
  return <Chat client={chatClient} i18nInstance={i18n}></Chat>;
};