List Objects in Production¶

Task: Connect to the DataONE production environment, retrieve the list of Objects, and print out the list.

First, load the dataone R package and connect to the production Coordinating Node:

In [23]:

library(dataone)
cn <- CNode()

listObjects accepts a number of optional arguments (see ?listObjects) such as count which controls the number of objects that are returned:

In [18]:

listObjects(cn, count = 5)

$objectInfo

$identifier

'0000120ce277dbb2e140d74b50ca23e5'

$formatId

'http://www.isotc211.org/2005/gmd-pangaea'

$checksum

$text: '0000120ce277dbb2e140d74b50ca23e5'
$.attrs: algorithm: 'MD5'

$dateSysMetadataModified

'2018-04-20T07:59:45.497+00:00'

$size

'19541'

$objectInfo

$identifier

'000026213216f47287f0d3027f3c4be3'

$formatId

'http://www.isotc211.org/2005/gmd-pangaea'

$checksum

$text: '000026213216f47287f0d3027f3c4be3'
$.attrs: algorithm: 'MD5'

$dateSysMetadataModified

'2018-04-20T05:09:36.311+00:00'

$size

'26256'

$objectInfo

$identifier

'0000aa6924377b6a7e5ab59bcec5d4f3'

$formatId

'http://www.isotc211.org/2005/gmd-pangaea'

$checksum

$text: '0000aa6924377b6a7e5ab59bcec5d4f3'
$.attrs: algorithm: 'MD5'

$dateSysMetadataModified

'2018-02-17T03:01:16.406+00:00'

$size

'35084'

$objectInfo

$identifier

'0000d11ff42b22915fcce5cfa6027040'

$formatId

'http://www.isotc211.org/2005/gmd-pangaea'

$checksum

$text: '0000d11ff42b22915fcce5cfa6027040'
$.attrs: algorithm: 'MD5'

$dateSysMetadataModified

'2018-01-06T10:43:32.073+00:00'

$size

'35257'

$objectInfo

$identifier

'0000eb4ff1fc59ae6c33a4981e00eabf'

$formatId

'http://www.isotc211.org/2005/gmd-pangaea'

$checksum

$text: '0000eb4ff1fc59ae6c33a4981e00eabf'
$.attrs: algorithm: 'MD5'

$dateSysMetadataModified

'2018-01-08T11:18:27.291+00:00'

$size

'49904'

$.attrs

count: '5'
start: '0'
total: '2897219'

As another example, we can filter to just CSV objects created within a time frame:

In [19]:

csvs <- listObjects(cn, 
                    fromDate = "2020-01-01T00:00:00.000Z", 
                    toDate = "2021-01-01T00:00:00.000Z", 
                    formatId = "text/csv", 
                    count = 5)
length(csvs$objectInfo)

5

You can see we received five results like we requested but there are many more available:

In [20]:

csvs$.attrs[3]

total: '28191'

Knowing this, we can use the start argument to page through the results:

In [ ]:

page_two <- listObjects(cn, 
                        fromDate = "2020-01-01T00:00:00.000Z", 
                        toDate = "2021-01-01T00:00:00.000Z", 
                        formatId = "text/csv", 
                        count = 5,
                        start = 5)

In [ ]:

page_two

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