How to find a Github file 's SHA blob

The docs for updating a file specify that you will need to provide the SHA for the file you will be replacing. The easiest way would be to query github for that, too. For example:

> curl https://api.github.com/repos/testacc01/testrepo01/contents/test.txt
{
  "name": "test.txt",
  "path": "test.txt",
  "sha": "4f8a0fd8ab3537b85a64dcffa1487f4196164d78",
  "size": 13,
 …

So, you can see what the SHA is in the "sha" field of the JSON response. Use that when you formulate your request to update the file with a new version. After you have successfully updated the file, the file will have a new SHA that you will need to request before it can be updated again. (Unless, I guess, your next update goes on a different branch.)

Using Octokit Rest API:

import { Octokit } from "@octokit/rest";

const { data: { sha } } = await octokit.request('GET /repos/{owner}/{repo}/contents/{file_path}', {
      owner: "owner-name",
      repo: "repo-name",
      file_path: "file-path-with-extension-from-root"
    });

If you don't want to hit the api, you could generate the SHA yourself. Git generates the SHA by concatenating a header in the form of blob {content.length} {null byte} and the contents of your file. For example:

content = "what is up, doc?"
header = "blob #{content.bytesize}\0"
combined = header + content # will be "blob 16\u0000what is up, doc?"
sha1 = Digest::SHA1.hexdigest(combined)

Source: https://git-scm.com/book/en/v2/Git-Internals-Git-Objects

If you use GraphQL API v4, you can use the following to find the sha of a specific file :

{
  repository(owner: "testacc01", name: "testrepo01") {
    object(expression: "master:test.txt") {
      ... on Blob {
        oid
      }
    }
  }
}

Try it in the explorer