Jira Scriptrunner script to Create/Update issues from text file

[David Kang]

Hi. I am trying to create a script to run a scheduled job of creating/updating issues everyday. I am reading the field values from a text file and parsing through the data to create issues. I am quite new to groovy and had a few questions.

1. From my understanding, the user will be the currently logged in user. In my case that the script can run without a user being logged in, how would I set the user?

def user = ComponentAccessor.getJiraAuthenticationContext().getUser()
//what i'm currently using

2. I am having a difficult time understanding how issues are stored into an object. 

a. When trying to create an issue, what is the process? I saw that there is an object called Issue and MutableIssue. Am i storing my field values into this Issue object and passing the object to a createissue function?

b. For updating issues, I am trying to find the issue by a jql query. Is this similar to create, where I find the issue, store the issue into an object, then pass the issue object to a updateissue function?

Anyone know where I can find some documentations or tutorials on how to create/update issues. On google, most of the results seem to be user specific problems and can't find a general way of creating/updating issues using Scriptrunner.