---
title: "Perform a ValueSet expansion"
method: POST
path: "/ValueSet/"
---

# Perform a ValueSet expansion

`POST /ValueSet/`

## Overview
To retrieve a subset of records from an individual CodeSystem, you will need to perform a 'POST' operation, in which you will provide the details of the CodeSystem you are searching, along with any filters to be applied and properties you wish to include in the results.

When you make a 'POST' operation, you perform an expansion on a ValueSet and provide a requestBody. The endpoint will return a successful (200) response code along with the search results, which may be an empty array if no records match your criteria. or an unsuccesful (4xx/5xx) response.

## Response `200`

a valid

## Other responses

- `4XX` — An error occurred as follows: | HTTP Code | issue.severity | issue.code | issue.details.code | issue.details.display | |------------ |----------------|---------------|---------------------|--------------------- | |400 |error |invalid |HAPI-1940 |Invalid Date/Time/Quantity format | |400 |error |invalid |HAPI-0524 |Unknown Search Parameter| |404 |error |invalid |HAPI-2001 |Organization not found | |405 |error |method not allowed|HAPI-0427 |Method Not Allowed | |422 |unprocessable |too-costly |Too many records requested (Use _count and _offset)|Invalid parameter | |422 |unprocessable |processing |No declared filter on Codesystem |An input field has an invalid value for its type |

---

[API](https://skmtc.net/nhs/apis/organisation-data-service-fhir-api.md) · [All operations](https://skmtc.net/nhs/apis/organisation-data-service-fhir-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/nhs/organisation-data-service-fhir-api/versions/6cf3c5d3b6d3/schema)