Query parameter versioning in Rest API - Step-by-Step Execution

Concept Flow - Query parameter versioning

Client sends request

↓

Check URL for version parameter

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Use specified

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API version

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Process request with chosen version

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Send response back

The server checks if the client request URL has a version parameter. If yes, it uses that API version; otherwise, it uses a default version to process the request.

Execution Sample

Rest API

GET /api/resource?version=2

Server reads 'version' param
Uses API version 2
Returns response for v2

This example shows a client requesting API version 2 using a query parameter, and the server responding accordingly.

Execution Table

Step	Request URL	Version Parameter Found?	Version Used	Action
1	/api/resource?version=2	Yes	2	Process request with API version 2
2	/api/resource	No	1 (default)	Process request with default API version 1
3	/api/resource?version=3	Yes	3	Process request with API version 3
4	/api/resource?ver=2	No	1 (default)	Process request with default API version 1

💡 Requests processed based on presence and value of 'version' query parameter; default used if missing or unrecognized.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4
request_url	/api/resource?version=2	/api/resource	/api/resource?version=3	/api/resource?ver=2	/api/resource?ver=2
version_param_found	false	true	false	true	false
version_used	1 (default)	2	1 (default)	3	1 (default)

Key Moments - 2 Insights

Why does the server use the default version when the URL has 'ver=2' instead of 'version=2'?

The server looks specifically for the 'version' query parameter. Since 'ver' is different, it is not recognized, so the default version is used (see execution_table row 4).

What happens if the version parameter is missing in the request URL?

If the 'version' parameter is missing, the server uses the default API version to process the request (see execution_table row 2).

Visual Quiz - 3 Questions

Look at the execution_table, what version is used at Step 3?

A 1 (default)

B 2

C 3

D No version used

💡 Hint

Check the 'Version Used' column at Step 3 in the execution_table.

At which step does the server NOT find the 'version' parameter?

A Step 2

B Step 3

C Step 1

D Step 4

💡 Hint

Look at the 'Version Parameter Found?' column in the execution_table.

If the client sends '/api/resource?version=5', what will the server likely do?

A Use default version 1 always

B Use version 5 if supported

C Ignore the version parameter

D Return an error immediately

💡 Hint

Servers usually use the version parameter value if recognized; see how version 2 and 3 are handled in execution_table.

Concept Snapshot

Query parameter versioning:
- Client adds '?version=x' to URL
- Server reads 'version' parameter
- If found, use that API version
- If missing, use default version
- Allows multiple API versions via URL

Full Transcript

Query parameter versioning means the client tells the server which API version to use by adding a 'version' parameter in the URL. The server checks if this parameter exists. If yes, it uses that version to process the request. If not, it uses a default version. For example, a request to '/api/resource?version=2' uses version 2 of the API. If the parameter is missing or named differently, like 'ver', the server uses the default version. This method helps servers support multiple API versions without changing the URL path.