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Custom properties and parameter substitution

Published: Not Available

Last Update: September 25, 2024

 

As defined in the Core LTI 1.3 specifications, Learn supports the addition of custom parameters to both the global tool configuration and a per-placement configuration. These can be defined as key-value pairs separated by equal signs (=). Additionally, Learn supports dynamic variables (also called parameter substitution in the specifications), where the value added in the launch will depend on the status of the environment at launch time.

Custom Parameters​

As mentioned, the custom parameters are key-value pairs that are added to the JWT token sent to your tool when the LTI Message Launch flow is completed. Each pair occupies a single line, and there is no limit on the amount of custom parameters that can be added. An example of the custom parameters is the following:

key1=some & value

The resulting value in the JWT token sent to your tool is the following:

"https://purl.imsglobal.org/spec/lti/claim/custom": {
    "key1": "some & value",
}

Parameter substitution​

To enhance this functionality, you can also use the custom dynamic variables defined in Dynamic Rendering with template Variables to get user, course or environment information at launch time.

Learn also supports the substitution variables defined in the LTI specification file here: https://www.imsglobal.org/spec/lti/v1p3#customproperty. The syntax is the same as a custom parameter (a key-value pair separated by an equal sign), but the variable from the specification must be preceded with a dollar sign, as seen here:

firstAvailable=$ResourceLink.available.startDateTime
userSysRoles=@X@user.role@X@

The resulting values on the launch will be:

"https://purl.imsglobal.org/spec/lti/claim/custom": {
    "firstAvailable": "2024-09-25T13:00:00Z",
    "userSysRoles": "Z",
}
No value to replace

In case the variable doesn't have a value stored for it (e.g: System role, enrollment start date, context history, etc), the system will send the string with the variable unaltered, as seen here:

The parameter:

groupId=$CourseGroup.id

The included value

"groupId": "$CourseGroup.id",