Untitled :: DataStax Astra DB Classic Documentation

Reading documents

Retrieving a specified document

Let’s check that the data was inserted for a particular document. Send a GET request to /api/rest/v2/namespaces/{namespace_name}/collections/{collections_name}/{document-id} to retrieve the document:

cURL command (/v2)
Result

curl -L \
-X GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness/{docid}' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{
	"documentId":"{docid}",
	"data":{
		"id":"some-stuff",
		"other":"This is nonsensical stuff."
	}
}

It is possible to get a value for a particular field in a document using one of two methods, either a where clause or a document-path. These methods can retrieve information from a document or a sub-document.

Retrieving a document using a where clause

Now let’s search for a particular document using a where clause. Send a GET request to /api/rest/v2/namespaces/{namespace_name}/collections/{collections_name}?{where-clause} to get the same information:

cURL command (/v2)
Result

curl -L -X  GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness?where=\{"firstname":\{"$eq":"Janet"\}\}' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{
	"data":{
		"Janet":{
			"email":"janet.doe@gmail.com",
			"favorite color":"grey",
			"firstname":"Janet",
			"lastname":"Doe"
		}
	}
}

Note that the where clause must be url encoded, so curly brackets are escaped with \ and spaces must be replaced with %20. Also, the full document is returned, as opposed to the value of the field specified in the {document-path} like the next command.

Read with `where`

You can also search with a multiple where clause. Send a GET request to /api/rest/v2/namespaces/{namespace_name}/collections/{collections_name}?{where-clause} to get the same information:

cURL command (/v2)
Result

curl -L -X  GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness?where=\{"firstname":\{"$eq":"Janet"\},"lastname":\{"$eq":"Doe"\}\}' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{
	"data":{
		"Janet":{
			"email":"janet.doe@gmail.com",
			"favorite color":"grey",
			"firstname":"Janet",
			"lastname":"Doe"
		}
	}
}

You can also retrieve documents using a WHERE clause that searches sub-documents:

cURL command (/v2)
Result

curl -L -X  GET 'lhttps://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness?where=\{"weights.type":\{"$eq":"bench%20press"\}\}' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{
	"data":{
		"Joey":{
			"firstname":"Joey",
			"lastname":"Doe",
			"weights":{
				"reps":15,
				"type":"bench press",
				"weight":150
			}
		}
	},
	"pageState":null
}

Multiple where can be used in a variety of cases. Here, a numerical value between to values is sought:

cURL command (/v2)
Result

curl -L -X  GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness?where=\{"weights.reps":\{"$gt":12\},"weights.reps":\{"$lt":20\}\}' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{
  "data": {
    "Joey": {
      "firstname": "Joey",
      "lastname": "Doe",
      "weights": {
        "reps": 15,
        "type": "bench press",
        "weight": 150
      }
    }
  }
}

Retrieving all documents

Let’s check that the document was inserted. Send a GET request to /api/rest/v2/namespaces/{namespace_name}/collections/{collections_name} to retrieve all the documents:

cURL command (/v2)
Result

curl --location \
--request GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness?page-size=3' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{
  "data":{
     "Joey":{
	"firstname":"Joey",
	"lastname":"Doe",
	"weights":{
		"reps":15,
		"type":"bench press",
		"weight":150
	}
     },
     "Janet":{
	"email":"janet.doe@gmail.com",
	"favorite color":"grey",
	"firstname":"Janet",
	"lastname":"Doe"
     },
     "{docid}":{
	"id":"some-stuff",
	"other":"This is nonsensical stuff."
     }
  }
}

The page-size parameter is included to get all the documents, rather than the last inserted document.

Retrieving all documents with Paging

For large collections, you can page a subset of the results. In this example, page-size is set to 5. Send a GET request to /api/rest/v2/namespaces/{namespace_name}/collections/{collections_name}page-size=5 to retrieve the first five documents (a page) in the collection:

cURL command (/v2)
Result

curl --location \
--request GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness?page-size=5' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{
  "pageState":"JGNlYjczMDc5LTE1NTItNGQyNS1hM2ExLWE2MzgxNWVlYTAyMADwf_____B_____",
  "data":{
    "58b12778-0efd-466e-89bf-66a4c99adee1":{"author":"Tom Clancy","title":"Red Rabbit"},
    "77fe8690-f8d4-43b8-b1c9-a328318d4eae":{"author":"Tom Clancy","title":"Every Man a Tiger"},
    "3177f86c-a633-4302-92a5-de4c15ab5840":{"author":"Tom Clancy","title":"Rainbow Six"},
    "cefc7117-fc73-47b8-a965-099cf3a59269":{"author":"Tom Clancy","title":"Clear and Present Danger"},
    "ceb73079-1552-4d25-a3a1-a63815eea020":{"author":"Tom Clancy","title":"The Cardinal of the Kremlin"}
  }
}

Pay close attention to the pageState value in the results. The pageState is a string representation a location in the result set. It is essentially an encoded shortcut that allows the final result set to be built from a specific point.

In order to get the next five documents, re-run the request with page-state parameter set to the first page’s pageState:

cURL command (/v2)
Result

curl -L -X  GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness/Joey/weights/type' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{"documentId":"Joey","data":"bench press"}

In this case, the sub-document weights is the document-path specified to retrieve that data about the reps, type, and weight.

cURL command (/v2)
Result

curl --location --request GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness/Joey/weights' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json'

{
	"documentId":"Joey",
	"data":{
		"reps":15,
		"type":"bench press",
		"weight":150
	}
}

Retrieving a specific portion of a document with document-path

Let’s add another record for the next example:

cURL command (/v2)
Result

curl -L -X PUT 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness/Martha' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header 'Content-Type: application/json' \
--data '{
    "firstname": "Martha",
    "lastname": "Smith",
    "weights": {
      "type": "bench press",
      "weight": 125,
      "reps": 12
  }
}'

{"documentId":"Martha"}

To find particular values, send a GET request to /api/rest/v2/namespaces/{namespace_name}/collections/{collections_name}/{document-id}/{document-path} to retrieve all the users that have, say, weight reps between 11 and 16:

cURL command (/v2)
Result

curl -L -X  GET 'https://$ASTRA_CLUSTER_ID-$ASTRA_REGION.apps.astra.datastax.com/api/rest/v2/namespaces/myworld/collections/fitness?where=\{"weights.*":\{"$gt":11\},"weights.*":\{"$lt":16\}\}&page-size=3' \
--header "X-Cassandra-Token: $ASTRA_DB_APPLICATION_TOKEN" \
--header "Content-Type: application/json"

{
  "data": {
    "Joey": {
      "firstname": "Joey",
      "lastname": "Doe",
      "weights": {
        "reps": 15,
        "type": "bench press",
        "weight": 150
      }
    },
    "Martha": {
      "firstname": "Martha",
      "lastname": "Smith",
      "weights": {
        "reps": 12,
        "type": "bench press",
        "weight": 125
      }
    }
  }
}