Is there any way to get a package's resource's field names/datatypes with downloading the entire resource?

Question

The CKAN <site>/api/3/action/package_show API provides a lot of metadata, but for tabular (row-column) resources I don't see any way to get the field names and datatypes other than by reading the resource itself and probably guessing at the datatypes. Am I missing anything?

Answer 1

If the site in question has enabled it, the CKAN's Datastore allows you to query tabular data directly via additional API functions. In your case you would probably use the datastore_info function to get the column names and data types for a given resource.

Here's an example of getting that information for some weather data (using the excellent HTTPie command line tool):

$ http post https://transparenz.karlsruhe.de/api/3/action/datastore_info id=117ae307-902a-4bf1-9c43-8b1aa9e8c2bd
HTTP/1.1 200 OK
Cache-Control: no-cache
Connection: keep-alive
Content-Length: 642
Content-Type: application/json;charset=utf-8
Date: Fri, 21 Jul 2017 11:25:19 GMT
Pragma: no-cache
Server: nginx/1.11.2
Strict-Transport-Security: max-age=31536000
Vary: X-Forwarded-Proto,X-Forwarded-Port

{
    "help": "https://transparenz.karlsruhe.de/api/3/action/help_show?name=datastore_info", 
    "result": {
        "meta": {
            "count": 3550
        }, 
        "schema": {
            "Apparent temperature (Degree Celcius)": "number", 
            "Atmospheric pressure (hPa; not normalized to sea level)": "number", 
            "Average wind speed (km/h; 10min window)": "number", 
            "Date and time (YYYY-MM-DD HH:MM:SS)": "date", 
            "Dew point (Degree Celcius)": "number", 
            "Global irradiance (W/m^2)": "number", 
            "Humidity (%)": "number", 
            "Maximum wind speed (km/h; 10min window)": "number", 
            "Precipitation (mm)": "number", 
            "Temperature (Degree Celcius)": "number", 
            "Wind direction (Degree)": "number"
        }
    }, 
    "success": true
}

You can check whether a CKAN instance is running the Datastore extension via the status_show API function.