# Liquid

When working with Elsa, you'll often want to write dynamic expressions. This page provides a glossary of various filters and tags you can use, in addition to the standard set that you can find in the [Liquid documentation](https://shopify.github.io/liquid/).

{% hint style="info" %}
Elsa uses the [Fluid library](https://github.com/sebastienros/fluid) to implement Liquid. More tags and filters can be found there, as well as details on providing your own tags and filters.
{% endhint %}

## Installing the Liquid Feature

The Liquid Expressions feature is provided by the following package:

```bash
dotnet add package Elsa.Expressions.Liquid
```

You can enable the feature as follows:

{% code title="Program.cs" %}

```csharp
services.AddElsa(elsa =>
{
   elsa.UseLiquid();
});
```

{% endcode %}

### Configuration

The `UseLiquid` extension provides an overload that accepts a delegate that lets you configure the `LiquidFeature`, which itself exposes a delegate to configure `FluidOptions`.

For example:

{% code title="Program.cs" %}

```csharp
services.AddElsa(elsa =>
{
   elsa.UseLiquid(liquid =>
   {
      liquid.FluidOptionstions += options =>
      {
         options.Encoder = HtmlEncoder.Default;
      }
   });
});
```

{% endcode %}

## Filters, Tags and Objects

The following filters, tags and objects are available to Liquid expressions:

* [Filters](#filters)
  * [json](#json)
  * [base64](#base64)
* [Objects](#objects)
  * [Variables](#variables)
  * [Input](#input)
  * [WorkflowInstanceId](#workflowinstanceid)
  * [WorkflowDefinitionId](#workflowdefinitionid)
  * [WorkflowDefinitionVersionId](#workflowdefinitionversionid)
  * [WorkflowDefinitionVersion](#workflowdefinitionversion)
  * [CorrelationId](#correlationid)

You can find more filters, tags and variables in the [Liquid documentation](https://shopify.github.io/liquid/).

### Filters

#### json

The `json` filter serialises an input value to a JSON string. Example:

```liquid
{{ some_value | json }}
```

#### base64

The base64 filter converts an input value into a base64 string. Example:

```liquid
{{ some_value | base64 }}
```

### Objects

#### Variables

The `Variables` object provides access to the workflow variables. For example, if your workflow has a variable called OrderId, you can get that workflow variable using the following Liquid expression:

```liquid
{{ Variables.OrderId }}
```

#### Input

The `Input` object provides access to workflow input. Example:

```liquid
{{ Input.OrderNumber }}
```

#### WorkflowInstanceId

The `WorkflowInstanceId` object provides access to the workflow instance ID of the currently executing workflow. Example:

```
{{ WorkflowInstanceId }}
```

#### WorkflowDefinitionId

The `WorkflowDefinitionId` object provides access to the workflow definition ID of the currently executing workflow. Example:

```
{{ WorkflowDefinitionId }}
```

#### WorkflowDefinitionVersionId

The `WorkflowDefinitionVersionId` object provides access to the workflow definition version ID of the currently executing workflow. Example:

```
{{ WorkflowDefinitionVersionId }}
```

#### WorkflowDefinitionVersion

The `WorkflowDefinitionVersion` object provides access to the workflow definition version of the currently executing workflow. Example:

```
{{ WorkflowDefinitionVersion }}
```

#### CorrelationId

The `CorrelationId` object provides access to the correlation ID of the currently executing workflow. Example:

```liquid
{{ CorrelationId }}
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.elsaworkflows.io/expressions/liquid.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.