graphql script to add a specific tag to all scenes in stashapp, try it in chrome developer console

stash_tag.js

let graphqlUrl = "http://ip:9999/graphql"

async function updateSceneTags(input) {
  return await fetch(graphqlUrl, {
    "headers": {
      "content-type": "application/json"
    },
    "body": JSON.stringify({
      query: `mutation MyMutation($input: [SceneUpdateInput!]!) {
        scenesUpdate(input: $input) { id }
      }`,
      variables: { input },
      operationName: "MyMutation"
    }),
    "method": "POST",
  });
}

async function getNontagged(tag_id) {
  const res = await fetch(graphqlUrl, {
    "headers": {
      "content-type": "application/json"
    },
    "body": JSON.stringify({
      query: `query MyQuery {
        findScenes(scene_filter: { tags: {value: "${tag_id}", modifier: EXCLUDES}}) {
          scenes { id }
        }
      }`
    }),
    "method": "POST",
  });
  return (await res.json()).data.findScenes.scenes
}

// it's not supported to mass tag an id-range
//  updateSceneTags([...Array(40).keys()].map(i => { return { id: i, tag_ids: [4] } }))
// because stash only takes 25 at a time, instead loop until no untagged videos left..
let nt = []
//const isOk = (l) => confirm((l.length ? l.length+" updated, continue?" : "update non-tagged videos?"))
const isOk = (l) => { console.log(l.length+" updated"); return (l.length > 0); }
const tag_id = 4
while(isOk(nt)) {
  nt = (await getNontagged(tag_id)).map(e => { e.tag_ids=[tag_id]; return e })
  await updateSceneTags(nt)
}