DNProject::resolveRevision PHP Method

    public function resolveRevision($value)
    {
        $repository = $this->getRepository();
        if (!$repository) {
            return false;
        }
        try {
            $revision = $this->repository->getRevision($value);
            return $revision->getCommit()->getHash();
        } catch (\Gitonomy\Git\Exception\ReferenceNotFoundException $e) {
            return false;
        }
    }

 /**
  * Create deployment. Can't use {@link create()} as it's taken by Object.
  *
  * @param \SS_HTTPRequest $request
  * @return \SS_HTTPResponse
  */
 public function createdeployment(\SS_HTTPRequest $request)
 {
     if ($request->httpMethod() !== 'POST') {
         return $this->getAPIResponse(['message' => 'Method not allowed, requires POST'], 405);
     }
     $this->checkSecurityToken();
     // @todo the strategy should have been saved when there has been a request for an
     // approval or a bypass. This saved state needs to be checked if it's invalidated
     // if another deploy happens before this one
     $sha = $this->project->resolveRevision($request->postVar('ref'));
     if (!$sha) {
         return $this->getAPIResponse(['message' => 'The given reference could not be resolved. Does it exist in the repository?'], 400);
     }
     // if a ref name was given that is not the sha, then set that. It could be a branch,
     // or tag name, or anything else that git uses as a named reference
     $refName = null;
     if ($request->postVar('ref_name') !== $request->postVar('ref')) {
         $refName = $request->postVar('ref_name');
     }
     $options = ['sha' => $sha, 'ref_type' => $request->postVar('ref_type'), 'ref_name' => $refName, 'title' => $request->postVar('title'), 'summary' => $request->postVar('summary')];
     if ($request->postVar('options')) {
         foreach (explode(',', $request->postVar('options')) as $option) {
             $options[$option] = true;
         }
     }
     $strategy = $this->createStrategy($options);
     $approver = Member::get()->byId($request->postVar('approver_id'));
     if ($approver && $approver->exists()) {
         if (!$this->project->allowed(ApprovalsDispatcher::ALLOW_APPROVAL, $approver)) {
             return $this->getAPIResponse(['message' => 'The given approver does not have permissions to approve'], 403);
         }
     }
     if ($request->postVar('id')) {
         $deployment = $strategy->updateDeployment($request->postVar('id'));
         $message = 'Deployment has been updated';
         $statusCode = 200;
     } else {
         $deployment = $strategy->createDeployment();
         $message = 'Deployment has been created';
         $statusCode = 201;
     }
     if ($approver && $approver->exists()) {
         $deployment->ApproverID = $approver->ID;
         $deployment->write();
     }
     $deploymentLink = \Controller::join_links(Director::absoluteBaseURL(), $deployment->Link());
     $response = $this->getAPIResponse(['message' => $message, 'location' => $deploymentLink, 'deployment' => $this->formatter->getDeploymentData($deployment)], $statusCode);
     $response->addHeader('Location', $deploymentLink);
     return $response;
 }