Update an existing trigger with tooling API

Question

I am able to create a trigger from a class using toolingAPI. Can I update this trigger using the Tooling API? Also, is it possible to update an existing visualforce page using the Tooling API? If so, can you please share the relevant code. I am sharing the code I used to create the trigger.

public class ToolingTrigger{

    public ToolingTrigger(VF_Page_Update_Controller controller) {

    }

    private static String baseUrl = URL.getSalesforceBaseUrl().toExternalForm() + '/services/data/v28.0/tooling/';

    public static void createTrigger() {

        String json = '{ "Name" : "TestAccountTrigger", "TableEnumOrId" : "Account", "Body" : "trigger TestAccountTrigger on Account (before insert) {}" }'; 

        Httprequest req = new HttpRequest(); req.setEndpoint(URL.getSalesforceBaseUrl().toExternalForm() + '/services/data/v27.0/sobjects/ApexTrigger'); 
        req.setMethod('POST'); 
        req.setHeader('Content-Type', 'application/json'); 
        req.setHeader('Authorization', 'OAuth ' + UserInfo.getSessionId()); 
        req.setBody(json); Http httpReq = new Http(); 
        HttpResponse res = httpReq.send(req); 
        System.debug(res.getBody()); 
    }
}

Answer 1

Tooling API support update also. It is regardless of Component type.

All you need to do is create "MetdataContainer" using Tooling API.

• Create Metadata Container

• Get the Trigger Id

• Change the body and add it to MetadataContainer.

• Perform the update call to MetdataContainer.

Look at following blog post section "Update Apex Class". Same way you can update Triggers. It is a long post so can't post everything here.

Below is the way to create MetdataContainer which hold all components to update (copied from blog):

public void createMetadataContainer()
{
    HttpRequest req = createHttpRequest(endpoint+'/sobjects/MetadataContainer','POST');
    req.setBody('{"Name":"ApexContainer"}');
    String response = getResponse(req);
    Map<String,Object> rmp = (Map<String,Object>)JSON.deserializeuntyped(response);
    String cid = (String)rmp.get('id'); // used to save containerId
}

Answer 2

I've experimented with this in our DX project and created a plugin for the SFDX CLI. I've posted it in this gist.

For our use case it did not do exactly what we wanted, but perhaps someone else can benefit from it. In a DX project, this mechanism will result in changes in the scratch org (changed timestamps), which have to be pulled into source control, which is an undesirable step. We've opted for the mechanism of first tweaking the source on disk, then pushing that code, doing the import, and then reverting back the changes using Git and pushing the original code again:

$ sed -i "s/<status>Active<\/status>/<status>Inactive<\/status>/" app/main/default/triggers/*-meta.xml
$ sfdx force:source:push -u org
# run import tool
$ git checkout -- app/main/default/triggers/*-meta.xml
$ sfdx force:source:push -u org