---
title: Brand Theme Selector Data Block
description: "*The Brand Theme Selector (BrandThemeSelector) Data Block is a System Data Block and cannot be deleted.* The Brand Theme Selector (BrandThemeSelector) Data Block is a Transform Data Block in Assette designed to return the appropriate brand theme name for a…"
url: "https://learn.assette.com/docs/brand-theme-selector-data-block/"
updated: "2025-03-31"
category: Developers / Data Blocks / Data Blocks by Category / System Data Blocks
---

# Brand Theme Selector Data Block

*The Brand Theme Selector (BrandThemeSelector) Data Block is a System Data Block and cannot be deleted.*

The Brand Theme Selector (BrandThemeSelector) Data Block is a Transform Data Block in Assette designed to return the appropriate brand theme name for a given product. This block supports branding logic for product-specific themes by retrieving brand theme values from a source and returning the matching entry based on a provided product code.

While the BrandThemeSelector Data Block is not required to use [Brand Themes](https://learn.assette.com/docs/brand-themes-overview/), it is required if firms plan on using the [Dynamic Brand Themes](https://learn.assette.com/docs/dynamic-branding-in-assette/).

## General Info

| Field | Value |
| --- | --- |
| Name | BrandThemeSelector |
| Block Category | Transform |
| Block Type | Python |
| Output Type | Text |
| Editable | True |

## Dependencies

This block depends on the following Data Blocks. These dependencies must be published and valid in the environment for this block to function correctly.

| Data Block | Description |
| --- | --- |
| CalculationEnv | Provides runtime environment variables or global configuration. [[Link](https://learn.assette.com/docs/calculation-env-data-block/)] |
| BrandThemeExtract | A Data Block that returns a list of available brand themes, each associated with a specific product. [[Link](https://learn.assette.com/docs/brand-theme-extract-data-block/)] |

## Example Definition

```
Product=""
if(params.__len__()>0):
    Product = params.get("ProductCode") or ""
BrandThemes = read("BrandThemeExtract", {})
BrandThemes = BrandThemes.get("data") or []
MatchingBrandTheme = {}
BrandThemeName = ""
if len(BrandThemes)>0:
    for BrandTheme in BrandThemes:
        if (BrandTheme.get("Product") or "") !="":
            if (BrandTheme.get("Product") or "")==Product:
                MatchingBrandTheme = BrandTheme
                break
if len(MatchingBrandTheme)>0:
    BrandThemeName = MatchingBrandTheme.get("BrandThemeName") or ""
response["text"] = BrandThemeName
```

## **How to Use This Block**

The BrandThemeSelector Data Block is used for [Dynamic Brand Themes](https://learn.assette.com/docs/dynamic-branding-in-assette/)— allowing branding to change based on the selected product. This ensures that documents reflect the correct visual theme or layout aligned with the selected investment product.

Example scenario:

- A fact sheet or client report dynamically selects colors, fonts, or logo placement based on the output of this block.
- The theme name returned by this block is used to trigger a corresponding theme setup in a presentation template.

## **Best Practices**

- Ensure that BrandThemeExtract contains accurate and up-to-date mappings of products to brand themes.
- Limit the number of themes to only those required, to keep performance optimized.
- Use clear and consistent naming for `ProductCode` and `BrandThemeName` values for easier maintenance.
- When editing this block, maintain the basic structure of the logic to preserve compatibility with downstream systems.