NoSQL

Apply a narrow edit to the reviewed version

BOTIE

Read version from the current record and compare it with expected before connecting the edited branch.
Ready to test
0 passed · 0 failed · 1 not run

An empty floor. Start with the information your machine needs.

Received result

Your answer will arrive here.

Examples, experiments and workspace controls
Live values

Connect a tool's inputs to see what it produces. You can try a branch before connecting it to Result.

Try your own inputs

Use a copy of the example to try your own data. Keep the problem's assumptions in mind, and predict the effect of a change before checking the output. You can also add another branch to compare two ways of doing the calculation.

Start at an output arrow, then click or drag to an input. Drag empty space to pan. Delete removes a selection. Ctrl/Cmd+Z undoes a change.
Context for this challenge

Read version from the current record and compare it with expected before connecting the edited branch.

Botie’s form may be older than the current pump document.

Inspect the component calculation
Compare exact scalar values(
  Stored value: Read a document path(
    Document: Current pump document
    Field path: version
  )
  Expected value: Version reviewed by the editor
)
Examples and results
Current pump document
{
  "asset_id": "P1",
  "version": 4,
  "status": "monitor",
  "notes": [
    "keep"
  ]
}
Version reviewed by the editor
4
Required result
true
Try a fresh construction

This clears this draft, including its undo history. Earlier successful attempts stay recorded. Build again without opening hints to record an independent attempt.

Stuck? Inspect a worked construction

The tools below form one possible solution. You can assemble it, follow its signals, and undo that change to return to your own construction.

Assumptions and test precision

The browser runs an explicit model of the mechanism. It does not connect to MongoDB or Redis, simulate their query planners, or establish their concurrency guarantees. Numerical tests allow a difference of 0.001. Lists and structures must also have the right shape.

Your last tested pieces can start the full construction. An existing draft there keeps its own pieces.

A retry still expects the previous version

This check uses the pieces from “Apply the status edit only to its expected version”.

BOTIE

The first edit has already left P8 at version 2 with status inspect. A retry still expects version 1. Predict the entire returned document without incrementing again.
Current pump document
{
  "asset_id": "P8",
  "version": 2,
  "status": "inspect",
  "notes": [
    "retained"
  ]
}
Version reviewed by the editor
1
Requested status
inspect

Use a number, text, or an array matching the requested result. For a matrix, put each row in brackets. Saving your prediction runs your current construction on these inputs and checks the earlier examples too.

Build a construction in the workspace above first. This case will test those pieces.

Why is a client-side read of version followed by an unconditional server write still unsafe?

The actual service must enforce the condition and transition atomically. The graph only models that rule.

The browser runs an explicit model of the mechanism. It does not connect to MongoDB or Redis, simulate their query planners, or establish their concurrency guarantees.

Work through the Python challenges →
Continue the courseCan We Find North’s Hot Pumps Without Reading Every Document? →