Get the preview

Read the latest generated preview — the proposed output, sheet-per-template — so your customer can review it before you execute.

GET https://app.vern.so/api/v1/migrations/{migration_id}/preview

Returns the current preview — the output of the latest generate or update run, mapped to your templates sheet-by-sheet. This is exactly what the agent proposes to import; show it to your customer, then refine or execute.

A migration has a preview once a generate/update run reaches awaiting_approval. Before that, this returns 404.

Authentication

Requires an x-api-key header. See Authentication.

Response

200 OK

{
  "status": "awaiting_approval",
  "templates": [
    { "slug": "contacts", "name": "Contacts" }
  ],
  "sheets": [
    {
      "template": { "slug": "contacts", "name": "Contacts" },
      "rows": [
        ["Email", "First Name", "Last Name", "Account"],
        ["[e-mail]", "Jane", "Doe", "Acme Corp"],
        ["[e-mail]", "John", "Smith", "Acme Corp"]
      ],
      "invalid_cells": []
    }
  ]
}

status · string

Always awaiting_approval when a preview exists.

templates · object[]

The templates this migration targets, each { slug, name }.

sheets · object[]

One entry per output sheet:

Show sheet

template · object

{ slug, name } — the template this sheet maps to.

rows · string[][]

The proposed rows as a grid, header row first.

invalid_cells · object[]

Cells flagged invalid in the preview. Empty in the common case.

Choosing columns

Two optional parameters shape which columns come back. Both default off, so leaving them out returns exactly what it always has.

fields · string

Comma-separated column names to return, in the order you give them. Matched exactly and case-sensitive. An unrecognised name returns 400 (unknown_field) listing the valid ones rather than being ignored — a typo should not quietly leave data out.

omit_empty · boolean · default: "false"

Drop columns that hold no data. A column is dropped only when it’s empty in every row, so the rows you get back all keep the same shape. Empty means an empty string, null, or an absent value; whitespace counts as data. Combine with fields and the pruning applies within your selection.

Here “empty” is judged from the rows in this response, which are the whole payload — a preview is a sample of what the plan would produce, so a column that’s empty in the sample may still be filled by the real import.

Errors

Status	Meaning
401	API key missing or invalid.
404	No preview generated yet, or the migration isn’t in your account.
429	30 requests per minute per account (the Reads class). Check Retry-After. See Rate limits.
500	Server error.

Example

curl https://app.vern.so/api/v1/migrations/c0a8012e-.../preview \
  -H "x-api-key: $VERN_API_KEY"

Next

• Start a run — update to refine, or execute to import.
• Export CSV — get the validated rows after execute.