JavaScript Expressions
The following JavaScript expressions are supported:
Contents
- JavaScript Expressions
- Variables
Variables
Workflow Variables
To access a workflow variable, use the getVariable function.
For example, if the SetVariable activity sets a variable called FirstName to ‘Luke’, it can be accessed as follows:
const firstName = getVariable('FirstName');
`Hello ${firstName}`
To set a workflow variable, use the setVariable function.
Activity Output
Any activity might provide some output, which is accessible from any other activity using workflow expressions. To access an activity’s output property called e.g. Output using a JavaScript expression, you can do so by specifying activities, then the activity name followed by .Output().
Notice that you must invoke the property as if it were a method. This is due to the way workflow storage providers work, which are potentially asynchronous in nature (such as Azure Blob Storage).
For example, if you have an activity named MyActivity, you can access its output as follows: activities.MyActivity.Output().
If the output is an object, you can access its properties too. For instance, the HTTP Endpoint activity returns the HTTP request as its output which is of type HttpRequestModel. When you name this activity "MyHttpEndpoint", you can access the HTTP request body like this:
activities.MyHttpEndpoint.Output().Body
If you happened to post a JSON document to your HTTP endpoint that looks like this:
{
"SomeDocument": {
"Title": "About Elsa Workflows"
}
}
Then you can access the “Title” field like this:
activities.MyHttpEndpoint.Output().Body.SomeDocument.Title
If your activity is a direct child of an HTTP Endpoint activity, you can access its output directly via the
inputvariable, which will be an instance ofHttpRequestModel.
SendHttpRequest Activity
The SendHttpRequest activity has two output properties:
[ActivityOutput] public HttpResponseModel? Response { get; set; }
[ActivityOutput] public object? ResponseContent { get; set; }
To access a SendHttpRequest activity with name SampleRequest1’s response content, use activities.SampleRequest1.ResponseContent().
input
Contains the input value that was received as output from the previously executed activity, if any.
input: object?
workflowInstanceId
Contains the workflow instance ID of the currently executing workflow.
workflowInstanceId: string
workflowDefinitionId
Contains the workflow definition ID of the currently executing workflow.
workflowDefinitionId: string
workflowDefinitionVersion
Contains the workflow definition version of the currently executing workflow.
workflowDefinitionVersion: number
correlationId
Contains the correlation ID of the currently executing workflow.
correlationId: string?
currentCulture
Contains the current culture.
currentCulture: CultureInfo
Currently, this value is always set to CultureInfo.InvariantCulture.
workflowContext
Contains the workflow context (if any) of the currently executing workflow.
workflowContext: object?
currentCulture
Returns the current culture.
currentCulture: CultureInfo
Common Functions
guid
Generates a new GUID value and returns its string representation.
guid(): string
This function is a thin wrapper around the following .NET code: Guid.NewGuid().ToString().
parseGuid
Parses a string into a GUID value.
parseGuid(value: string): Guid
This function is a thin wrapper around the following .NET code: Guid.Parse(value).
setVariable
Sets a workflow variable to the specified value.
setVariable(name: string, value: object): void
This function is a thin wrapper around the following .NET code: activityContext.SetVariable(name, value).
getVariable
Returns a workflow variable with the specified name.
getVariable(name: string): object
Instead of using getVariable(name: string), you can access workflow variables directly as described above in the Workflow Variables section.
This function is a thin wrapper around the following .NET code: activityContext.GetVariable(name).
getTransientVariable
Returns a transient workflow variable with the specified name.
getTransientVariable(name: string): object
This function is a thin wrapper around the following .NET code: activityContext.GetTransientVariable(name).
getConfig
Provides access to a .NET configuration value.
getConfig(name: string): string
This is a security-sensitive function and is therefore not available by default. You need to enable this function through a setting. To enable this function, Enable it in Admin -> Settings -> Config Access.
As an example, let’s say you have the following JSON in appsettings.json:
{
"Elsa": {
"Smtp": {
"Host": "localhost",
"Port": 2525
}
}
}
You can access the configured Port value using the following expression:
getConfig("Elsa:Smtp:Port") // returns '2525'
This function is a thin wrapper around the following .NET code: configuration.GetSection(name).Value where configuration is an instance of IConfiguration.
isNullOrWhiteSpace
Returns true if the specified string is null, empty or consists of white space only, false otherwise.
isNullOrWhiteSpace(value: string): boolean
This function is a thin wrapper around the following .NET code: string.IsNullOrWhiteSpace(value).
isNullOrEmpty
Returns true if the specified string is null or empty, false otherwise.
isNullOrEmpty(value: string): boolean
This function is a thin wrapper around the following .NET code: string.IsNullOrEmpty(value).
Workflow Functions
getWorkflowDefinitionIdByName
Returns the ID of the specified workflow by name. This is useful when for instance you are using the RunWorkflow activity, which requires the ID of the workflow definition to run.
getWorkflowDefinitionIdByName(name: string): string?
getWorkflowDefinitionIdByTag
Returns the ID of the specified workflow by tag. This is useful when for instance you are using the RunWorkflow activity, which requires the ID of the workflow definition to run.
getWorkflowDefinitionIdByTag(tag: string): string?
HTTP Functions
queryString
Returns the value of the specified query string parameter.
queryString(name: string): string
absoluteUrl
Converts the specified relative path into a fully-qualified absolute URL.
absoluteUrl(path: string): string
signalUrl
Generates a fully-qualified absolute signal URL that will trigger the workflow instance from which this function is invoked.
signalUrl(signal: string): string
Date/Time Functions
instantFromDateTimeUtc
Returns a new Instant object from the specified DateTime value.
Make sure that the DateTime value’s Kind property is DateTimeKind.Utc.
currentInstant
Returns the current date/time value in the form of a NodaTime’s Instant object.
currentInstant(): Instant
currentYear
Returns the current year.
currentYear(): number
startOfMonth
Returns the start of the month of the specified instant. If no instant is specified, the current instant is used.
startOfMonth(instant: Instant?): LocalDate;
endOfMonth(instant: Instant?)
Returns the end of the month of the specified instant. If no instant is specified, the current instant is used.
endOfMonth(instant: Instant?): LocalDate;
startOfPreviousMonth
Returns the start of the previous month of the specified instant. If no instant is specified, the current instant is used.
startOfPreviousMonth(instant: Instant?): LocalDate;
plus
Adds the specified Duration to the specified Instant and returns the result.
plus(instant: Instant, duration: Duration): Instant
minus
Subtracts the specified Duration from the specified Instant and returns the result.
minus(instant: Instant, duration: Duration): Instant
durationFromDays
Returns a duration constructed from the specified number of days.
durationFromDays(days: number): Duration
formatInstant
Formats the specified Instant using the specified format string and CultureInfo. If no culture info is provided, CultureInfo.InvariantCulture is used.
formatInstant(instant: Instant, format: string, cultureInfo: CultureInfo?): string
localDateFromInstant
Returns the LocalDate portion of the specified Instant.
localDateFromInstant(instant: Instant): LocalDate
instantFromLocalDate
Creates an Instant from the specified LocalDate value (start of date).
instantFromLocalDate(localDate: LocalDate): Instant