Bicycle Parking Register with Spring Boot: A 2027 Project Guide

The starting point for this Spring Boot exercise is a campus mobility volunteer working with parking_entry records. Their question is specific: How many bicycles are currently parked by zone? Building a layered REST feature around that question gives the project a manageable scope and makes the result possible to verify.

This is a 2027 study-edition project brief. All example records and operational situations are fictional. Start with basic Spring Boot knowledge, the ability to inspect structured data and a local practice environment. The complete first version should answer the stated question before adding accounts, real integrations or additional screens.

Define the project rule

Parked counts describe currently occupied positions in this simplified exercise. Released entries leave the occupancy measure; a capacity limit requires a separate validated field. For this exercise, one row represents one parking_entry. The stable key is record_id; parking_zone is the grouping or filtering label. The numeric bicycle_count field uses bicycles. Accepted states are requested, parked, released.

The summary selects status parked and applies sum to the selected numeric values. Keep this definition visible in the interface, response or report so another learner can reproduce it. Use positive finite values in the starter fixture and define any future zero or missing-value policy explicitly.

Choose the Spring Boot approach

Keep HTTP binding in a controller, the decision in a service and persistence behind a repository boundary. Translate invalid input into a documented response. Test the service independently before adding infrastructure, then verify the full request path. Put environment-specific configuration outside source files and describe the assumptions of the local database.

The three design decisions to explain in your project notes are:

• Controller-service separation. Apply this choice to parking_entry records and explain its effect on bicycle_count.
• Validation at the request boundary. Apply this choice to parking_entry records and explain its effect on bicycle_count.
• Transactional business updates. Apply this choice to parking_entry records and explain its effect on bicycle_count.

Work through a small sample

The three records below are deliberately small enough to inspect by hand. They are a compact specification for the data shape and expected result, and can later be expanded into a larger synthetic fixture.

[
  {
    "record_id": "bicycle-parking-01",
    "parking_zone": "North Rack",
    "bicycle_count": 2,
    "status": "parked",
    "recorded_on": "2027-01-04"
  },
  {
    "record_id": "bicycle-parking-02",
    "parking_zone": "Library Rack",
    "bicycle_count": 1,
    "status": "requested",
    "recorded_on": "2027-01-05"
  },
  {
    "record_id": "bicycle-parking-03",
    "parking_zone": "Workshop Rack",
    "bicycle_count": 3,
    "status": "parked",
    "recorded_on": "2027-01-06"
  }
]

Only the first and third records match parked. Their bicycle_count values are 2 and 3; the full-fixture result is 5 bicycles, with 2 matching records. Selecting parking_zone = North Rack leaves the first record, so the result becomes 2 bicycles, with 1 match. This provides two independent checks for the filter and aggregation.

The full-fixture output contract is:

{
  "matching_count": 2,
  "operation": "sum",
  "value": 5,
  "unit": "bicycles"
}

Check the result by parking_zone

The overall figure answers the all-records version of the question. Grouping by parking_zone produces the following separate expectations, using the same parked rule. The middle group has a record in the source fixture but no qualifying observation.

Use this breakdown when answering the group-level question. Compare like-for-like units and keep the matching count visible, especially for averages. A different filter changes which records enter the calculation; it does not change the meaning of the metric.

The code blocks describe sample data and an expected result. Implement the surrounding feature using the installed version of your chosen tools, then save the actual run evidence separately from these expectations.

Build the feature in three passes

1. Describe the request contract

Define a read operation for the parking_entry collection and an optional parking_zone filter. Document accepted status values and the positive numeric bicycle_count field. Decide how the client receives validation details before implementing a write operation.

2. Place the rule in a service

Calculate the sum for parked records inside a request-independent function. Keep persistence access separate. Return a count, value and bicycles label so a consumer can distinguish an empty set from an actual measured result.

3. Verify the stored outcome

Start with the fixture, execute one controlled change, and read it back. A rejected update must leave the collection unchanged. If the application uses memory only, document its restart behaviour instead of implying that the data is durable.

Find the mistake before polishing the result

A useful defect to introduce deliberately is: Released entries remain in the occupancy summary. First reproduce it against the fixture, then identify the smallest rule or state transition that explains the mismatch. Fix that boundary and rerun the full-fixture and selected-label examples. This creates a stronger explanation than changing several unrelated parts until the screen looks right.

The scenario-specific acceptance check is: Release one entry and reconcile the remaining parked quantity. Preserve before-and-after evidence. Add a missing parking_zone, a negative bicycle_count, an unrecognised status and a duplicate record_id as separate invalid cases. Define the rejection or duplicate-handling policy before testing, and verify that invalid input does not silently change valid existing records.

Check the Spring Boot concerns as well:

• Invalid requests must not reach persistence.
• A failed write must not look successful.
• The service test must not require an HTTP server.

For an empty filter match, the expected sum value is 0. Keep matching_count at zero. This distinction prevents an empty dataset from being interpreted as a measured observation.

Explain the finished work in a portfolio

Show the campus mobility volunteer question, the record definition and the expected calculation first. Then demonstrate a parking_zone filter and the acceptance check. Include the fixture, setup instructions, chosen tool versions, actual test output and one remaining limitation in the repository. If you show a screenshot, pair it with the input that produced it. Another learner should be able to repeat the same result from a clean checkout.

For a focused extension, add a second parking_zone selection and compare the two groups using the same rule. Specify how missing groups appear and keep the original fixture as a regression case. Expand scope only after the current calculation, state handling and recovery path remain understandable.

Questions learners often ask

Which parking_entry records belong in the result?

Select records whose status is exactly parked and that satisfy the chosen parking_zone filter. Other states remain in the source data and can have separate summaries. Follow the domain rule above when a record changes state.

What should happen when no records match?

Return a zero total with a matching count of zero and a clear empty-result message. Keep the applied filter visible so the user can change it. Avoid using a loading indicator for a completed request that simply has no matching data.

How can I prove the bicycle_count result is correct?

Reconcile the first and third sample records, then repeat the calculation for North Rack alone. Save both expected and actual outputs, and rerun the scenario-specific acceptance check after making a change.

Continue learning with Groot Academy

Use this exercise as a concrete discussion point when choosing a learning path. Explore the related Groot Academy course and ask about the current syllabus, learning mode and project practice. Course availability and batch details should be confirmed directly with the academy.

For implementation details, consult the official Spring Boot documentation matching the tools you install. This project defines an original practice brief; it does not depend on a forecast about 2027 software releases.

Continue with Campus Shuttle Seat Requests using Spring Boot, or compare Bicycle Parking Register using Java Microservices. These companion practice guides are part of the 2027 learning collection.