Sample Post Install Script for a Push Upgrade

 Hi,

In this sample script, the package upgrade contains new Visualforce pages and a new permission set that grants access to those pages. The script performs the following actions.

• Gets the Id of the Visualforce pages in the old version of the package
• Gets the permission sets that have access to those pages
• Gets the list of profiles associated with those permission sets
• Gets the list of users who have those profiles assigned
• Assigns the permission set in the new package to those users

Eg:

global class PostInstallClass implements InstallHandler {

    global void onInstall(InstallContext context) {

        //Get the Id of the Visualforce pages 

        List<ApexPage> pagesList = [SELECT Id FROM ApexPage WHERE NamespacePrefix =  

            'TestPackage' AND Name = 'vfpage1'];

        //Get the permission sets that have access to those pages

        List<SetupEntityAccess> setupEntityAccessList = [SELECT Id, 

            ParentId, SetupEntityId, SetupEntityType FROM SetupEntityAccess 

            WHERE SetupEntityId IN :pagesList];        

        Set<ID> PermissionSetList = new Set<ID> ();

        for (SetupEntityAccess sea : setupEntityAccessList) {

            PermissionSetList.add(sea.ParentId);

        }

        List<PermissionSet> PermissionSetWithProfileIdList = 

            [SELECT id, Name, IsOwnedByProfile, Profile.Name,

            ProfileId FROM PermissionSet WHERE IsOwnedByProfile = true 

            AND Id IN :PermissionSetList];   

        //Get the list of profiles associated with those permission sets

        Set<ID> ProfileList = new Set<ID> ();

        for (PermissionSet per : PermissionSetWithProfileIdList) {

            ProfileList.add(per.ProfileId);

        }

        //Get the list of users who have those profiles assigned

        List<User> UserList = [SELECT id FROM User where ProfileId IN :ProfileList];                

        //Assign the permission set in the new package to those users

        List<PermissionSet> PermissionSetToAssignList = [SELECT id, Name 

            FROM PermissionSet WHERE Name='TestPermSet' AND 

            NamespacePrefix = 'TestPackage'];

        PermissionSet PermissionSetToAssign = PermissionSetToAssignList[0];

        List<PermissionSetAssignment> PermissionSetAssignmentList = new List<PermissionSetAssignment>();

        for (User us : UserList) {

            PermissionSetAssignment psa = new PermissionSetAssignment();

            psa.PermissionSetId = PermissionSetToAssign.id;

            psa.AssigneeId = us.id;

            PermissionSetAssignmentList.add(psa);

        }

        insert PermissionSetAssignmentList;

    }

}

Test Class:

// Test for the post install class

@isTest

private class PostInstallClassTest {

    @isTest           

    public static void test() {

      PostInstallClass myClass = new PostInstallClass();

      Test.testInstall(myClass, null);

    }

}         

Referene:

https://developer.salesforce.com/docs/atlas.en-us.sfdx_dev.meta/sfdx_dev/push_upgrade_post_install_script.htm