--- title: CRUD Data Store description: Auto-generate a fully functional REST CRUD API over an in-memory JSON data store using a single PUT /mockserver/crud request, with no expectations required. shortTitle: CRUD Data Store layout: page pageOrder: 9.6 section: 'Mock Server' subsection: true sitemap: priority: 0.7 changefreq: 'monthly' lastmod: 2026-06-01T08:00:00+00:00 ---

The CRUD data store lets you stand up a complete REST API for a JSON resource with a single control-plane request. MockServer registers list, get, create, update, and delete endpoints automatically, backed by an in-memory store. No expectations need to be written by hand.

This is useful for tests that need a stateful resource API — for example, a /users service where test cases create, update, and delete records independently.

Registering a CRUD resource

Send a PUT request to /mockserver/crud with a JSON body describing the resource. MockServer registers the endpoints immediately and returns a confirmation.

Request fields

Field	Type	Required	Default	Description
basePath	string	yes		Root path for the resource (e.g. /users). Must start with /, must not be /, and must not overlap /mockserver.
idField	string	no	id	Name of the JSON field used as the unique identifier in each item.
idStrategy	string enum	no	AUTO_INCREMENT	AUTO_INCREMENT — assigns sequential numeric ids starting at 1. UUID — assigns a random UUID string.
initialData	array of objects	no	null	Optional seed records to pre-populate the store. Each object must contain the id field; existing id values are preserved and the auto-increment counter is advanced past the highest numeric id found.

Example request

PUT /mockserver/crud HTTP/1.1
Content-Type: application/json

{
  "basePath": "/users",
  "idField": "id",
  "idStrategy": "AUTO_INCREMENT",
  "initialData": [
    {"id": 1, "name": "Alice", "email": "alice@example.com"},
    {"id": 2, "name": "Bob",   "email": "bob@example.com"}
  ]
}

Response (201 Created)

{
  "basePath" : "/users",
  "idField" : "id",
  "idStrategy" : "AUTO_INCREMENT",
  "itemCount" : 2
}

Generated endpoints

After registration MockServer handles the following standard REST operations on the basePath. These are served by MockServer's own dispatcher before expectation matching, so they do not consume expectation slots.

Method	Path	Description	Success status
GET	{basePath}	Return all items as a JSON array, in insertion order.	200
POST	{basePath}	Create a new item. MockServer assigns the id automatically (AUTO_INCREMENT or UUID) and returns the stored item.	201
GET	{basePath}/{id}	Return a single item by id. Returns 404 if not found.	200
PUT	{basePath}/{id}	Replace an item by id. The id field in the stored item is always set to the path id. Returns 404 if not found.	200
PATCH	{basePath}/{id}	Partially update an item by id. Only the fields present in the request body are merged into the existing item (shallow merge). The id field cannot be changed via PATCH. Returns 404 if not found.	200
DELETE	{basePath}/{id}	Delete an item by id. Returns 404 if not found.	204

Limits and lifecycle

Each store holds up to 10,000 items by default. A POST that would exceed this limit returns 507 Insufficient Storage.
The in-memory store is cleared when MockServer is reset (PUT /mockserver/reset). Re-register the CRUD resource after a reset if needed.
Multiple CRUD resources can be registered at different base paths simultaneously.
Registering the same basePath a second time replaces the existing handler and resets its store.

Example usage

# Register the resource
curl -s -X PUT http://localhost:1080/mockserver/crud \
  -H 'Content-Type: application/json' \
  -d '{"basePath":"/users","idStrategy":"AUTO_INCREMENT"}'

# Create a record
curl -s -X POST http://localhost:1080/users \
  -H 'Content-Type: application/json' \
  -d '{"name":"Alice","email":"alice@example.com"}'
# -> {"id":1,"name":"Alice","email":"alice@example.com"}

# List all records
curl -s http://localhost:1080/users
# -> [{"id":1,"name":"Alice","email":"alice@example.com"}]

# Get by id
curl -s http://localhost:1080/users/1
# -> {"id":1,"name":"Alice","email":"alice@example.com"}

# Update (full replace)
curl -s -X PUT http://localhost:1080/users/1 \
  -H 'Content-Type: application/json' \
  -d '{"name":"Alice Smith","email":"alice@example.com"}'

# Partial update (PATCH - only change the email, keep the name)
curl -s -X PATCH http://localhost:1080/users/1 \
  -H 'Content-Type: application/json' \
  -d '{"email":"alice.smith@example.com"}'
# -> {"id":1,"name":"Alice Smith","email":"alice.smith@example.com"}

# Delete
curl -s -X DELETE http://localhost:1080/users/1