API Request Log with Python: A 2027 Project Guide

A student backend developer needs a trustworthy answer to a small operational question: what is the mean duration of successful requests by endpoint group? This Python project turns that question into a command-line processor. The useful result is a traceable decision rule, a clear output and evidence that a change behaves as expected.

This is a 2027 study-edition project brief. All example records and operational situations are fictional. Start with basic Python 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

Average response time is calculated for successful sample requests. Failed requests need their own count rather than being dropped without explanation, and a mean alone does not describe tail latency. For this exercise, one row represents one request. The stable key is record_id; endpoint_group is the grouping or filtering label. The numeric response_ms field uses milliseconds. Accepted states are started, succeeded, failed.

The summary selects status succeeded and applies mean 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 Python approach

Keep parsing, validation and calculation in separate functions. Read the fixture without changing it, reject malformed rows with an explanatory message, and return a new result object. A short script is easier to debug when the calculation can be called without opening files or reading keyboard input.

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

• Functions and return values. Apply this choice to request records and explain its effect on response_ms.
• Dictionaries keyed by stable identifiers. Apply this choice to request records and explain its effect on response_ms.
• Explicit exception handling. Apply this choice to request records and explain its effect on response_ms.

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": "api-request-log-01",
    "endpoint_group": "Catalogue",
    "response_ms": 120,
    "status": "succeeded",
    "recorded_on": "2027-01-04"
  },
  {
    "record_id": "api-request-log-02",
    "endpoint_group": "Reservations",
    "response_ms": 300,
    "status": "started",
    "recorded_on": "2027-01-05"
  },
  {
    "record_id": "api-request-log-03",
    "endpoint_group": "Reports",
    "response_ms": 180,
    "status": "succeeded",
    "recorded_on": "2027-01-06"
  }
]

Only the first and third records match succeeded. Their response_ms values are 120 and 180; the full-fixture result is 150 milliseconds, with 2 matching records. Selecting endpoint_group = Catalogue leaves the first record, so the result becomes 120 milliseconds, with 1 match. This provides two independent checks for the filter and aggregation.

The full-fixture output contract is:

{
  "matching_count": 2,
  "operation": "mean",
  "value": 150,
  "unit": "milliseconds"
}

Check the result by endpoint_group

The overall figure answers the all-records version of the question. Grouping by endpoint_group produces the following separate expectations, using the same succeeded 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. Read and validate the fixture

Parse each request into a consistent shape. Check record_id, endpoint_group, response_ms and status before performing a calculation. Return useful errors for malformed records, and keep file handling outside the function that applies the rule.

2. Implement a reference calculation

Select records whose status is succeeded, then apply the mean operation to response_ms. Return the matching count with the result. Keeping the count visible makes it easier to detect an accidental denominator or filtering error.

3. Exercise the function at its boundaries

Call the same function with all records, a endpoint_group filter and an empty match. Print the original collection afterwards to check for mutation. Save a compact result object so a later interface can reuse the calculation.

Find the mistake before polishing the result

A useful defect to introduce deliberately is: Failed requests disappear from every visible measure. 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: Display a failure count separately from successful-request mean duration. Preserve before-and-after evidence. Add a missing endpoint_group, a negative response_ms, 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 Python concerns as well:

• A second invocation must return the same result.
• Unknown states must not silently become valid.
• The input collection must remain unchanged.

For an empty filter match, the expected mean value is undefined (no matching observations). 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 student backend developer question, the record definition and the expected calculation first. Then demonstrate a endpoint_group 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 endpoint_group 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 request records belong in the result?

Select records whose status is exactly succeeded and that satisfy the chosen endpoint_group 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?

Treat the empty result as undefined and show a clear no-observations 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 response_ms result is correct?

Reconcile the first and third sample records, then repeat the calculation for Catalogue 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 Python 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 Service Health Checks using Python, or compare API Request Log using Core Java. These companion practice guides are part of the 2027 learning collection.