# ReferenceExpressionBuilder

- Module: [Aspire.Hosting](/reference/api/typescript/aspire.hosting.md)
- Version: `13.2.0`
- Kind: `handle`
- Source: [GitHub](https://github.com/microsoft/aspire)

## Definition

```typescript
interface ReferenceExpressionBuilder {
  readonly isEmpty: boolean;
  appendFormatted(
      value: string,
      format?: string): void;
  appendLiteral(value: string): void;
  appendValueProvider(
      valueProvider: any,
      format?: string): void;
  build(): ReferenceExpression;
}
```

## Properties

- `isEmpty`: `boolean` `get` -- Gets the IsEmpty property

## Methods

- [appendFormatted](/reference/api/typescript/aspire.hosting/referenceexpressionbuilder/appendformatted.md) -- `method` -- Appends a formatted string value to the reference expression
    ```typescript
  appendFormatted(value: string, format?: string): void
  ```
- [appendLiteral](/reference/api/typescript/aspire.hosting/referenceexpressionbuilder/appendliteral.md) -- `method` -- Appends a literal string to the reference expression
    ```typescript
  appendLiteral(value: string): void
  ```
- [appendValueProvider](/reference/api/typescript/aspire.hosting/referenceexpressionbuilder/appendvalueprovider.md) -- `method` -- Appends a value provider to the reference expression
    ```typescript
  appendValueProvider(valueProvider: any, format?: string): void
  ```
- [build](/reference/api/typescript/aspire.hosting/referenceexpressionbuilder/build.md) -- `method` -- Builds the reference expression
    ```typescript
  build(): ReferenceExpression
  ```