Computing Custom Date Format Patterns Throughout an Application

If you want to ensure consistency in date formatting throughout your application, you can define the pattern for each Edit Box or Computed Value control that displays a date. What you may not have considered is that you can compute the date format, so you can define it in one place and use the same format everywhere. In this post, I’ll show how you can set it up and even change it conditionally.

Locale Conversions

The browser will automatically attempt to format dates based on your specified locale. Here’s an example of a computed field set to display a date. The Display type must be set to Date/Time.

Date Format 1a Default Date Format - Settings

Here’s how it displays in my browser when the language is set to English:

Date Format 1b Default Date - English

Here’s how it displays when I change my browser language to French:
Date Format 1c Default Date - French

Custom Date Patterns

If you want to change the default formatting, you can define a custom date format pattern.

To define a specific pattern, change Display format to Custom and then you can edit the Pattern field. (You can select a pre-defined pattern or enter your own.)

Date Format 2 - Custom Date Format

In this case, the pattern will stay the same, regardless of the browser language.

(Note: When defining a date pattern, the month value uses one or more capital M’s, because the lower case m is for minutes when defining a time pattern.)

Computing Date Patterns

Just like most other properties in XPages, there’s a blue diamond next to the Pattern field, allowing you to use SSJS to compute it. This gives you the opportunity to create a library function to return some pattern to use. Then, you can set all of your date controls to call the same function and modify the pattern in one place.

Your library function could be as simple as this:

function getDateFormat() {
  return 'dd-MMM-yyyy';
}

Taking it one step further, you could add logic in the function to conditionally determine the pattern, whether it be based on a user preference or a locale or just changing date formatting patterns on a daily basis because you like to mess with your users.

If you use more complex logic, you may also want to consider storing the pattern in an applicationScope variable, so it’s available throughout the application.

function getDateFormat() {
  if (!applicationScope.dateFormat) {
    // Logic to determine date format
    applicationScope.put('dateFormat', some_date_format);
  }

  return applicationScope.dateFormat;
}

Computation Timing

The default setting for the logic Compute Dynamically (#). If you leave it that way, it will throw this error when you load the page: The value of the property pattern cannot be a run time
binding.

To fix this, select Compute on Page Load when entering/editing the snippet or change the octothorpe/pound sign/hash (#) to a dollar sign ($) in the page source, because date pattern computations only work on page load.

Compute Date Formats - 3

Quick Replace

If you’ve already set up hard-coded patterns on date fields, they would look something like this:

You can do a quick search and replace to modify them all easily.

Search for:

pattern="dd-MMM-yyyy"

Compute Date Formats - 4a

Click the Replace... button rather than the Search button.

Then replace with:

pattern="${javascript:return getDateFormat();}"

Compute Date Formats - 4b

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2 responses to “Computing Custom Date Format Patterns Throughout an Application”

  1. david says :

    I’m using notes9 ,facing a isuue as I change Display Format to “custom” , but the pattern is still locked, is there something else I had to setup?

    thanks

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