# ReferenceExpression

Term type: API type

A structured expression that combines text and resource value references without resolving those references too early.

Also known as: reference expression

A `ReferenceExpression` retains the structure of a value assembled from endpoints, parameters, connection strings, and literal text.

At runtime, value providers can resolve the expression to concrete values. During publishing, a publisher can preserve or translate references into its own representation.

Do not eagerly concatenate an unresolved endpoint into plain text when authoring an integration. Once the structure is lost, a publisher cannot reliably recover the dependency information from the string.

## Practical example

Compose a database connection string from an endpoint and a secret parameter while preserving both references for run or publish mode.

## Learn more

- [Compose resource values with expressions](https://aspire.dev/architecture/resource-hierarchies/)

## Related terms

- [Connection string](https://aspire.dev/hub/glossary/connection-string/)

- [Deferred evaluation](https://aspire.dev/hub/glossary/deferred-evaluation/)

- [Hoisting](https://aspire.dev/hub/glossary/hoisting/)