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Placeholders let you insert dynamic values from entity data into text fields at runtime. They use the &{...} syntax and work across most text fields in Alumio, such as values in the Value setter, templates in the Merger, and URL paths in HTTP transformers. Placeholders are different from patterns — patterns navigate data, placeholders interpolate values into strings.

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Syntax

SyntaxDescription
&{product.name}The value at product.name in the entity
&{products.0.sku}The sku of the first product
&{@}The entire output of the current transformer
@{globals.<key>}A global variable set by the Global variable setter

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Examples

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Value setter

Set a field to a concatenated string: Key: full_name Value: &{first_name} &{last_name} If the entity contains first_name: "Jane" and last_name: "Doe", the result is: 
{
    "full_name": "Jane Doe"
}

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Merger

Merge HTTP transformer output into the entity using a placeholder: Template: { "response": "&{@}" } This captures the full output of the HTTP transformer and stores it under response.

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HTTP transformer URL

Use entity data in a request URL: URL: https://api.example.com/products/&{product.id} If product.id is 42, the request goes to https://api.example.com/products/42.

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Notes

  • Placeholders resolve at runtime — if the referenced path does not exist in the entity, the placeholder is replaced with an empty string.
  • &{@} is only available in contexts that wrap a transformer output, such as the Merger.
  • Global variables (@{globals.<key>}) must be set earlier in the route using the Global variable setter transformer.