It may happen that your implementation sends additional date information, such as the date of first time an app was launched, in the custom attributes of customers. If that date has a different format than the one required by Decision Hub, you can use Expressions to transform it. The example in this article explains how to transform a date in `dd.mm.yyyy` format into a timestamp that can be used in Decision Hub. In the custom attributes of the customer profile, the parameter that stores the date is called `app_first_started`. If you're an advanced user, you can modify the regular expressions in the article to work with different formats of dates in the parameter. ## Prerequisites --- - Implementation of [tracking code](/developers/web/installation-and-configuration#creating-a-tracking-code) on your website. - The attribute with the date (in this example, it's `app_first_started`) must be defined. This can be done in one of the following ways: - [Add the attribute in **Profile attributes**](/docs/crm/customer-properties#adding-profile-attributes-in-the-synerise-portal). - Create or update a customer with the attribute (using the API or SDK). ## Process --- The process consists of three stages: 1. [Create expressions to extract elements of the date](#create-expressions-to-extract-elements-of-the-date). 2. [Create an expression to re-arrange the elements of the date into a format that can be converted into a timestamp](#create-an-expression-to-re-arrange-the-elements-of-the-date). 3. [Convert the date into a timestamp](#convert-into-a-timestamp).

Due to event data retention, such attributes should be stored permanently in a customer's profile, not in event data.

In the course of this procedure, you can use the **Show in profile card** toggle in each expression to preview the results in a test customer's profile.

## Create expressions to extract elements of the date --- Three separate expressions are used to extract the day, month, and year. The only difference between them is the regular expression used. 1. Go to

**Behavioral Data Hub > Expressions > New expression**. 2. From the **Expressions for** dropdown list, select **Attribute**. 3. In the **Formula definition** section, click **Select**. 4. From the list that opens, select **Function > Regexp**. 5. In the brackets, click the left **Select** button and from the list, select **Profile**. 7. Click the **unnamed** node that appeared. 8. At the bottom of the page, click **Choose attribute**. 9. In the list of attributes, find and select `app_first_started` (you can use the search field). 10. In the brackets, click the right **Select** button and from the list, select **Constant**. 11. Click the **0** node that appeared. 12. At the bottom of the page, in the input field, paste the regular expression that extracts the day: `(?<=^)(\d*?)(?=\.)` 13. Above the formula creator, enter a meaningful name for the expression.

Expression to extract the day from a date in `dd.mm.yyyy` format

14. In the upper-right corner, click **Save**. 15. In the upper-right corner, click **Publish**. 16. Create the month and year expression by performing the following steps twice: 1. Return to the list of expressions and locate the expression you created. 2. To the right, click the

icon and select **Duplicate**. 3. Click the duplicated expression to open it for editing. 4. Change the name of the expression. 5. In the **Formula definition** section, click the node with the regular expression. 6. Change the regular expression to: - For month: `(?<=\.)(\d*?)(?=\.)` - For year: `(?<=\.)(\d*?)(?=$)` 7. Click **Publish**. ## Create an expression to re-arrange the elements of the date --- In this stage, you create an expression that concatenates (joins) the results of the three expressions above into a single string in `yyyy/mm/dd` format. This format can later be converted into a timestamp. 1. Go to

**Behavioral Data Hub > Expressions > New expression**. 2. Create the following attribute expression:

Expression to concatenate the elements of a date

**Explanation**: - **Concat** is a function. - Expression results (green nodes) are treated and inserted like customer attributes. - `/` is a constant. The expression takes three strings (year, month, day) that are the results of the expressions you created before and joins them into one string with `/` as the separator. 3. Click **Save**. 4. Click **Publish**. ## Convert into a timestamp --- In this stage, convert the `yyyy/mm/dd` date into an Analytics-compatible timestamp. 1. Go to

**Behavioral Data Hub > Expressions > New expression**. 2. Create the following expression:

Expression that converts yyyy/mm/dd into a timestamp — Expression that converts `yyyy/mm/dd` into a timestamp

**Explanation:** - **To timestamp** is a function. - Expression results are treated and inserted like customer attributes. 3. Click **Save**. 4. Click **Publish**. ## What's next --- You can now use the result of the last expression (called "Timestamp from yyyy/mm/dd" in this example) as a timestamp in analytics, for example to create a segmentation of customers who first started the app after a certain date or to find the transactions that a customer made before they first started the application. If you enabled the **Show in profile card** toggles, the expression results are visible in the right panel of a customer card in **Profiles**:

Expression results in a customer profile

## Check the use case set up on the Synerise Demo workspace --- You can find five expressions created in this use case in our Synerise Demo workspace at the links listed below: - [expression used to extract the day](https://app.synerise.com/analytics/expressions/4b67b443-c5bd-4637-9f52-a05b5d77ca33) - [expression used to extract the month](https://app.synerise.com/analytics/expressions/f2e2409c-3dff-4205-89b6-5d0525b31e64) - [expression used to extract the year](https://app.synerise.com/analytics/expressions/257b0362-a181-4d21-bfe7-82a8f89ba513) - [expression to re-arrange the elements of the date](https://app.synerise.com/analytics/expressions/3f330b8a-7d11-4ab9-88c4-946a3c3d83b8) - [expression for timestamp from yyyy/mm/dd](https://app.synerise.com/analytics/expressions/25677e70-e82f-4932-8329-1883fb00fe3d) If you’re our partner or client, you already have automatic access to the **Synerise Demo workspace (1590)**, where you can explore all the configured elements of this use case and copy them to your workspace. If you’re not a partner or client yet, we encourage you to fill out the contact [form](https://demo.synerise.com/request) to schedule a meeting with our representatives. They’ll be happy to show you how our demo works and discuss how you can apply this use case in your business. ## Read more --- - [Expressions](/docs/analytics/expressions)