# Class SubstitutionsProcessor

OptimaJet.Workflow.Core.CodeActions.SubstitutionsProcessor

Expands process parameter placeholders embedded in action, condition, and rule parameters, annotation values, and other text evaluated for a process instance.

Namespace: [OptimaJet.Workflow.Core.CodeActions](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.CodeActions/)

```csharp
public static class SubstitutionsProcessor
```

## Methods

`public static Task<(string newValue, bool wasSubstituted)> SubstituteAsync(string value, ProcessInstance processInstance)` 

Replaces process parameter placeholders in `value` with values resolved through `processInstance`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `value` | `String` | The text to inspect for parameter placeholders. |
| `processInstance` | `ProcessInstance` | The [ProcessInstance](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ProcessInstance/) that supplies parameter values for replacements. |

### Returns

| Type | Description |
| --- | --- |
| `Task<String, Boolean>` | A tuple containing the transformed text and [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) when at least one placeholder was matched; otherwise, the original text and [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool). |

### Exceptions

| Type | Description |
| --- | --- |
| `Exception` | Thrown when a parameter resolves to [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null) and its placeholder specifies a nonempty format other than `json`. |
| `RegexMatchTimeoutException` | Thrown when placeholder matching exceeds the one-second regular-expression timeout. |

### Remarks

Placeholders use the `@ParameterName` or `@(ParameterName)` form recognized by [RegexPattern.ParameterAndMaybeQuotes](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.CodeActions/RegexPattern/). Parentheses can delimit a placeholder from adjacent text and allow spaces in parameter names. Dotted names resolve values within structured parameters.

A nonempty format after `:` is passed to the value's `ToString(string)` overload. The special `json` format serializes the value with [ParametersSerializer](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Runtime/ParametersSerializer/). Matching single or double quotes immediately around the entire placeholder are consumed as part of the match: ordinary replacements are emitted in double quotes, while a `json` replacement is inserted as a serialized JSON value.

### Example

`Order @Order.Id was created on @(CreatedAt:yyyy-MM-dd)` substitutes a nested parameter value and a formatted date. `@(Payload:json)` inserts the serialized parameter value.

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