# Class ParametersCollection

OptimaJet.Workflow.Core.Model.ParametersCollection

Represents the collection of process parameters owned by a [ProcessInstance](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ProcessInstance/).

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

```csharp
public sealed class ParametersCollection : IEnumerable<ParameterDefinitionWithValue>, IEnumerable
```

## Type Hierarchy

-   ParametersCollection Current type
    -   Implemented interfaces
        -   [IEnumerable](https://learn.microsoft.com/dotnet/api/system.collections.ienumerable)
        -   [IEnumerable<ParameterDefinitionWithValue>](https://learn.microsoft.com/dotnet/api/system.collections.generic.ienumerable-1)

## Constructors

`public ParametersCollection(List<ParameterDefinitionWithValue> parameters, ProcessInstance owner)` 

Initializes a new instance of the [ParametersCollection](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParametersCollection/) class with `parameters`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameters` | `List<ParameterDefinitionWithValue>` | The [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) objects to store in the collection. |
| `owner` | `ProcessInstance` | The [ProcessInstance](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ProcessInstance/) that owns the process parameters. |

### Exceptions

| Type | Description |
| --- | --- |
| `ArgumentNullException` | `parameters` or `owner` is [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). |

`public ParametersCollection(IEnumerable<ParameterDefinitionWithValue> parameters, ProcessInstance owner)` 

Initializes a new instance of the [ParametersCollection](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParametersCollection/) class by copying `parameters`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameters` | `IEnumerable<ParameterDefinitionWithValue>` | The sequence of [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) objects used to populate the collection. |
| `owner` | `ProcessInstance` | The [ProcessInstance](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ProcessInstance/) that owns the process parameters. |

### Exceptions

| Type | Description |
| --- | --- |
| `ArgumentNullException` | `parameters` or `owner` is [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). |

`public ParametersCollection(ProcessInstance owner)` 

Initializes an empty instance of the [ParametersCollection](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParametersCollection/) class.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `owner` | `ProcessInstance` | The [ProcessInstance](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ProcessInstance/) that owns the process parameters. |

### Exceptions

| Type | Description |
| --- | --- |
| `ArgumentNullException` | `owner` is [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). |

## Methods

`public IEnumerator<ParameterDefinitionWithValue> GetEnumerator()` 

### Returns

| Type | Description |
| --- | --- |
| `IEnumerator<ParameterDefinitionWithValue>` |  |

`public void AddParameter(ParameterDefinitionWithValue parameter)` 

Adds `parameter`, replacing any parameters with the same parameter name.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameter` | `ParameterDefinitionWithValue` | The [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) to add. |

`public void AddParameters(IEnumerable<ParameterDefinitionWithValue> parameters)` 

Adds `parameters`, replacing current parameters with matching parameter names.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameters` | `IEnumerable<ParameterDefinitionWithValue>` | The [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) objects to add. |

`public void ReplaceParameters(List<ParameterDefinitionWithValue> parameters)` 

Replaces the process parameters in the collection with `parameters`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `parameters` | `List<ParameterDefinitionWithValue>` | The [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) objects that become the collection contents. |

`public bool IsParameterExisting(string name)` 

Determines whether the collection contains a process parameter or nested property identified by `name` with a non-[null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null) value.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The parameter name or dot-separated path to a nested property. |

### Returns

| Type | Description |
| --- | --- |
| `Boolean` | [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) if the parameter or nested property has a non-[null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null) value; otherwise, [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool). |

`public ParameterDefinitionWithValue GetParameter(string name)` 

Gets the parameter or nested parameter property identified by `name`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The parameter name or dot-separated path to a nested property. |

### Returns

| Type | Description |
| --- | --- |
| `ParameterDefinitionWithValue` | The matching [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/), or [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null) if no parameter is found or a nested value is [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). |

`public Task<ParameterDefinitionWithValue> GetParameterAsync(string name)` 

Asynchronously gets the parameter or nested parameter property identified by `name`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The parameter name or dot-separated path to a nested property. |

### Returns

| Type | Description |
| --- | --- |
| `Task<ParameterDefinitionWithValue>` | A [Task<TResult>](https://learn.microsoft.com/dotnet/api/system.threading.tasks.task-1) whose result is the matching [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/), or [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null) if no parameter is found or a nested value is [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). |

`public T GetParameter<T>(string name)` 

Gets the value of the parameter or nested parameter property identified by `name`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The parameter name or dot-separated path to a nested property. |

### Returns

| Type | Description |
| --- | --- |
| `{T}` | The value as `T`, or the default value of `T` if no value is found. |

### Remarks

When `T` is a reference type other than [string](https://learn.microsoft.com/dotnet/api/system.string) and the result is not [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null), reading a process parameter whose [ParameterDefinition.Purpose](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinition/) is [ParameterPurpose.Persistence](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterPurpose/) and whose [ParameterDefinitionWithValue.IsImplicit](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) is [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) marks the containing [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) as modified.

### Example

If the `Order` parameter contains a nested `Customer.Name` property, `parameters.GetParameter<string>("Order.Customer.Name")` returns that property's value.

`public Task<T> GetParameterAsync<T>(string name)` 

Asynchronously gets the value of the parameter or nested parameter property identified by `name`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The parameter name or dot-separated path to a nested property. |

### Returns

| Type | Description |
| --- | --- |
| `Task<T>` | A [Task<TResult>](https://learn.microsoft.com/dotnet/api/system.threading.tasks.task-1) whose result is the value as `T`, or the default value of `T` if no value is found. |

### Remarks

When `T` is a reference type other than [string](https://learn.microsoft.com/dotnet/api/system.string) and the result is not [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null), reading a process parameter whose [ParameterDefinition.Purpose](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinition/) is [ParameterPurpose.Persistence](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterPurpose/) and whose [ParameterDefinitionWithValue.IsImplicit](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) is [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) marks the containing [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) as modified.

### Example

If the `Order` parameter contains a nested `Customer.Name` property, `await parameters.GetParameterAsync<string>("Order.Customer.Name")` returns that property's value.

`public void SetParameter<T>(string name, T value, ParameterPurpose purposeIfMissing = ParameterPurpose.Temporary)` 

Sets the value of the parameter or nested parameter property identified by `name`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The parameter name or dot-separated path to a nested property. |
| `value` | `{T}` | The value to assign. |
| `purposeIfMissing` | `ParameterPurpose` | The [ParameterPurpose](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterPurpose/) assigned to a missing implicit parameter. When `purposeIfMissing` is [ParameterPurpose.Persistence](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterPurpose/), a missing explicit parameter defined in [ProcessDefinition.Parameters](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ProcessDefinition/) is also created as a persistent parameter. |

### Example

`parameters.SetParameter("Order.Customer.Name", "Alice")` assigns `"Alice"` to the nested `Name` property of `Customer` in the `Order` parameter.

`public Task SetParameterAsync<T>(string name, T value, ParameterPurpose purposeIfMissing = ParameterPurpose.Temporary)` 

Asynchronously sets the value of the parameter or nested parameter property identified by `name`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The parameter name or dot-separated path to a nested property. |
| `value` | `{T}` | The value to assign. |
| `purposeIfMissing` | `ParameterPurpose` | The [ParameterPurpose](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterPurpose/) assigned to a missing implicit parameter. When `purposeIfMissing` is [ParameterPurpose.Persistence](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterPurpose/), a missing explicit parameter defined in [ProcessDefinition.Parameters](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ProcessDefinition/) is also created as a persistent parameter. |

### Returns

| Type | Description |
| --- | --- |
| `Task` | A [Task](https://learn.microsoft.com/dotnet/api/system.threading.tasks.task) that represents the asynchronous operation. |

### Example

`await parameters.SetParameterAsync("Order.Customer.Name", "Alice")` assigns `"Alice"` to the nested `Name` property of `Customer` in the `Order` parameter.

`public void SetImplicitSerializedParameter(string name, string value, ParameterPurpose purposeIfMissing = ParameterPurpose.Temporary)` 

Sets the implicit process parameter identified by `name` from the JSON-serialized value in `value`.

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The name of the implicit parameter. |
| `value` | `String` | The JSON-serialized parameter value. |
| `purposeIfMissing` | `ParameterPurpose` | The [ParameterPurpose](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterPurpose/) to assign if the implicit parameter must be created. |

`public void RemoveParameter(string name, bool removeFromCollection = false)` 

Sets the process parameter or nested property identified by `name` to [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null), or removes the top-level parameter from the collection when `removeFromCollection` is [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool).

### Parameters

| Name | Type | Description |
| --- | --- | --- |
| `name` | `String` | The parameter name or dot-separated path to a nested property. A path is supported only when `removeFromCollection` is [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool). |
| `removeFromCollection` | `Boolean` | [true](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) to remove the top-level [ParameterDefinitionWithValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinitionWithValue/) from the collection; [false](https://learn.microsoft.com/dotnet/csharp/language-reference/builtin-types/bool) to set the parameter or nested property value to [null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null). |

`public void InitPersistenceParametersFromScheme()` 

Initializes process parameters from non-[null](https://learn.microsoft.com/dotnet/csharp/language-reference/keywords/null) [ParameterDefinition.InitialValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinition/) values for definitions in [ProcessDefinition.Parameters](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ProcessDefinition/) whose [ParameterDefinition.Purpose](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinition/) is [ParameterPurpose.Persistence](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterPurpose/).

### Exceptions

| Type | Description |
| --- | --- |
| `InvalidJsonParameterValueException` | A persistent parameter other than [string](https://learn.microsoft.com/dotnet/api/system.string) has a [ParameterDefinition.InitialValue](https://api.workflowengine.io/core/OptimaJet.Workflow.Core.Model/ParameterDefinition/) that cannot be deserialized from JSON. |

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