"timestamp/SystemMessage": "{{ timestamp | timestampFormatter(format: YYYY) }}",
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 inChannelList
.ImageGalleryHeader
- Component showing the header in theImageGallery
.InlineDateSeparator
- Component separating groups of messages inMessageList
.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 theMessageList
/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.
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 thetimestamp
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 aBoolean
field to decide if the date format should be in calendar format or not. The default value isfalse
.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 any of the calendarFormats
keys are missing, then the underlying library will fall back to hard-coded english equivalents
If calendar
formatting is enabled, the format
prop would be ignored. So to apply the format
string, the calendar
has to be disabled.
The described rules follow the formatting rules required by the i18n library used under the hood - i18next
. You can learn more about the rules in the formatting section of the i18next
documentation.
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>;
};