---
title: "Fetch an asset object"
method: GET
path: "/{assetObjectHref}"
tags: ["Data"]
---

# Fetch an asset object

`GET /{assetObjectHref}`

Return an asset object

### Notes on Caching

Asset objects are cached by default for 2 hours (7200 seconds). Depending on the
update interval of an asset object (e.g. for frequently updated data)
the `Cache-Control` header can be different, in special cases it can even be
set to `no-cache` (e.g. for realtime data).

All endpoints support the precondition headers `If-Match` and `If-None-Match`.
To reduce unnecessary traffic it's highly recommended to use these headers
(mostly `If-None-Match`) when making calls.

In case your application is using frequently updated data and you want to
be sure not to miss an update of the data, the recommended procedure is as
follows:

```python
import requests
import time

refresh_interval = 60

item_etag = "*"
item_url = "https://data.geo.admin.ch/collections/{collectionID}/items/{itemId}"

asset_id = 'data.json'
asset_etag = "*"

poll_for_new_data = True

while(poll_for_new_data):
  item_response = requests.get(item_url, headers={'If-None-Match': f'"{item_etag}"'})
  if item_response.status_code == 304:
    # item metadata and hence any associated asset object didn't
    # change since last call

    time.sleep(refresh_interval)

  elif item_response.status_code == 200:
    # item metadata has changed since last visit

    item_etag = item_response.headers.get("ETag") # save the new etag
    asset_href = item_response.json['assets'][asset_id]['href'] # save the asset href

    obj_response = requests.get(asset_href, headers={'If-None-Match': f'"{asset_etag}"'})
    if obj_response.status_code == 304:
      # "our" asset object didn't change since last call,
      # we can ignore that the item metadata changed,
      # it was a different asset that has changed

      time.sleep(refresh_interval)

    elif obj_response.status_code == 200:
      # "our" asset object has changed, we load the new data

      asset_etag = obj_response.headers.get("ETag")  # save the new asset etag
      asset_checksum = obj_response.headers.get("X-Amz-Meta-Sha256")
      object = obj_response.data

      # calculate the sha256 checksum of the data in a proper way
      checksum = calc_checksum(object)
      if checksum != asset_checksum:
        # Error: corrupted data from download
        # do proper error handling

      # do sth with the data
    else:
      # do proper error handling
  else:
    # do proper error handling
```

## Headers

- `If-None-Match` string

## Response `200`

The asset object

## Other responses

- `304` — The cached resource was not modified since last request.
- `404` — The specified asset object was not found
- `412` — Some condition specified by the request could not be met in the server

---

[API](https://skmtc.net/geoadmin/apis/the-spatiotemporal-asset-catalog-api-for-data-geo-admin-ch.md) · [All operations](https://skmtc.net/geoadmin/apis/the-spatiotemporal-asset-catalog-api-for-data-geo-admin-ch/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/geoadmin/the-spatiotemporal-asset-catalog-api-for-data-geo-admin-ch/versions/015864bb4d77/schema)