Lab 5: CRUD Operations

Learning Objectives

By the end of this lab, you'll understand:

  • ✅ How to implement PUT requests (update entire resource)
  • ✅ How to implement PATCH requests (partial update)
  • ✅ How to implement DELETE requests (resource removal)
  • ✅ How to use request bodies with JSON payloads
  • ✅ How to load request bodies from files
  • ✅ How to test complete CRUD workflows

Real-World Scenario

So far you've tested GET and POST. But real APIs do more:

  • POST /users → Create user, get back ID
  • GET /users/:id → Retrieve user
  • PUT /users/:id → Replace entire user
  • PATCH /users/:id → Update only some fields
  • DELETE /users/:id → Remove user

A realistic performance test must include the full CRUD lifecycle.

Concept: CRUD Methods

POST (Create)

.exec(http("Create user")
    .post("/users")
    .body(StringBody("{\"name\": \"Alice\", \"email\": \"alice@example.com\"}"))
    .check(status().is(201))
    .check(jsonPath("$.id").saveAs("userId"))
)

GET (Read)

.exec(http("Get user")
    .get("/users/#{userId}")
    .check(status().is(200))
)

PUT (Update - Replace All)

.exec(http("Update user")
    .put("/users/#{userId}")
    .body(StringBody("{\"name\": \"Bob\", \"email\": \"bob@example.com\"}"))
    .check(status().is(200))
)

PATCH (Update - Partial)

.exec(http("Patch user")
    .patch("/users/#{userId}")
    .body(StringBody("{\"email\": \"newemail@example.com\"}"))
    .check(status().is(200))
)

DELETE (Remove)

.exec(http("Delete user")
    .delete("/users/#{userId}")
    .check(status().is(204))
)

Code Pattern: Complete CRUD Scenario

ScenarioBuilder crudJourney = scenario("CRUD Operations")
    // 1. CREATE
    .exec(http("Create user")
        .post("/users")
        .body(StringBody("{\"name\": \"Test User\", \"email\": \"test@example.com\"}"))
        .check(status().is(201))
        .check(jsonPath("$.id").saveAs("userId"))
    )
    .pause(1)

    // 2. READ
    .exec(http("Get user")
        .get("/users/#{userId}")
        .check(status().is(200))
        .check(jsonPath("$.name").is("Test User"))
    )
    .pause(1)

    // 3. UPDATE (PUT)
    .exec(http("Update user (PUT)")
        .put("/users/#{userId}")
        .body(StringBody("{\"name\": \"Updated User\", \"email\": \"updated@example.com\"}"))
        .check(status().is(200))
    )
    .pause(1)

    // 4. PARTIAL UPDATE (PATCH)
    .exec(http("Patch user (PATCH)")
        .patch("/users/#{userId}")
        .body(StringBody("{\"email\": \"patch@example.com\"}"))
        .check(status().is(200))
    )
    .pause(1)

    // 5. DELETE
    .exec(http("Delete user")
        .delete("/users/#{userId}")
        .check(status().is(204))
    );

Loading Request Bodies from Files

// Instead of: .body(StringBody("{...}"))
// Use: .body(new FileBody("bodies/create_user.json"))

.exec(http("Create user from file")
    .post("/users")
    .body(new FileBody("bodies/create_user.json"))
    .check(status().is(201))
)

Running the Lab

cd /Users/sgovinda/Learn/GatlingLearning

mvn gatling:test -Dgatling.simulationClass=io.learn.gatling.simulations.http.Sim05_CRUD

Expected Results

  • ✅ 200+ total requests (40 per user)
  • ✅ >99% success rate
  • ✅ p95 latency <2000ms
  • ✅ All CRUD operations work
  • ✅ POST returns 201
  • ✅ GET returns 200
  • ✅ PUT/PATCH return 200
  • ✅ DELETE returns 204

Key Takeaways

  1. POST = Create (201 Created)
  2. GET = Read (200 OK)
  3. PUT = Replace all (200 OK)
  4. PATCH = Update partial (200 OK)
  5. DELETE = Remove (204 No Content)
  6. Status codes matter - verify in checks
  7. Body loading from files keeps code clean

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