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copyright lastupdated keywords subcollection
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2015, 2020
2020-04-20
getting started, example, connect to service instance, create a database, populate database, retrieve data, queries, retrieve data, api endpoint, delete database, close connection, python code, couchdb-as-a-service, couchdb hosted, couchdb, databases for couchdb
cloudant

{:new_window: target="_blank"} {:shortdesc: .shortdesc} {:screen: .screen} {:codeblock: .codeblock} {:pre: .pre} {:tip: .tip} {:note: .note} {:important: .important} {:deprecated: .deprecated} {:external: target="_blank" .external}

Getting started with {{site.data.keyword.cloudant_short_notm}}

{: #getting-started-with-cloudant}

In this {{site.data.keyword.cloudantfull}} getting started tutorial, we use Python to create an {{site.data.keyword.cloudant_short_notm}} database and populate that database with a simple collection of data. You can retrieve data by using queries or API endpoints. {: shortdesc}

For more information, see our hands-on tutorials that help you learn more about {{site.data.keyword.cloudant_short_notm}}. Or try one of the tutorials that focuses on a specific language:

For more language-specific tutorials, see Get started by deploying your first app{: new_window}{: external}.

Before you begin

{: #prereqs}

Verify that you have what you need to start the tutorial from the following list:

  1. To check the Python version installed on your machine, run the following command:

      python3 --version

    {: pre}

  2. Verify that your version matches the most recent version. The result looks something like this:

    Python 3.8.1

    {: screen}

    • The Cloudant Python library enables your Python applications to work with {{site.data.keyword.cloudant_short_notm}} on {{site.data.keyword.cloud_notm}}.

  3. To check that the client library is already installed, run the following command at a prompt:

      pip3 freeze

    {: pre}

    You see a list of all the Python modules that are installed on your system. Review the list, looking for an {{site.data.keyword.cloudant_short_notm}} entry similar to the following one:

    cloudant==<version>

    {: screen}

  4. If the cloudant module isn't installed, install it by using a command similar to the following one.

    pip3 install cloudant

    {: pre}

    For more information about the Python library, see the supported platforms documentation.

Step 1. Connect to your {{site.data.keyword.cloudant_short_notm}} service instance on {{site.data.keyword.cloud_notm}}

{: #step-1-connect-to-your-cloudant-nosql-db-service-instance-on-ibm-cloud}

  1. Run the python3 command to start the Python interactive shell. 
    python3
    {: codeblock}

Python 3 interactive shell{: caption="Figure 1. Python 3 interactive shell" caption-side="bottom"}

  1. Run the import statements of the {{site.data.keyword.cloudant_short_notm}} Client Library components to enable your Python application to connect to the {{site.data.keyword.cloudant_short_notm}} service instance.

    from cloudant.client import Cloudant
from cloudant.error import CloudantException
from cloudant.result import Result, ResultByKey

    {: codeblock}

  2. Create an {{site.data.keyword.cloudant_short_notm}} service credential:

a. In the {{site.data.keyword.cloud_notm}} dashboard, go to the Menu icon > Resource List, and open your {{site.data.keyword.cloudant_short_notm}} service instance.

b. In the menu, click Service credentials.

c. Click the New credential button.

Create new service credentials.{: caption="Figure 2. Create new service credentials" caption-side="bottom"}

d. Enter a name for the new credential in the Add new credential window, as shown in the following screen capture.

e. (Optional) Add inline configuration parameters.

f. Click the Add button.

Add a service credential.{: caption="Figure 3. Add a service credentials" caption-side="bottom"}

Your credentials are added to the Service credentials table.

g. Click View credentials under Actions.

View all service credentials.{: caption="Figure 4. View all service credentials" caption-side="bottom"}

The details for the service credentials appear:

The {{site.data.keyword.cloudant_short_notm}} service credentials{: caption="Figure 5. The {{site.data.keyword.cloudant_short_notm}} service credentials" caption-side="bottom"}

  1. Establish a connection to the {{site.data.keyword.cloudant_short_notm}} service instance. The way {{site.data.keyword.cloudant_short_notm}} establishes this connection depends on whether you're using {{site.data.keyword.cloud_notm}} Identity and Access Management (IAM) or {{site.data.keyword.cloudant_short_notm}} Legacy authentication. For more information about either authentication type, see the IAM guide.

    If you're using {{site.data.keyword.cloudant_short_notm}} Legacy authentication, replace your service credentials from the previous step.

    client = Cloudant("<username>", "<password>", url="<url>")
client.connect()

    {: codeblock}

    If you're using IAM authentication, replace your service credentials from the previous step.

    client = Cloudant.iam("<username>", "<apikey>")
client.connect()

    {: codeblock}

Step 2. Create a database

{: #step-2-create-a-database}

  1. Define a variable in the Python application:
database_name = "<your-database-name>"

{: codeblock}

... where <your-database-name> is the name you would like to give your database.

The database name must begin with a letter and can include only lowercase characters (a-z), numerals (0-9), and any of the following characters _, $, (, ), +, -, and /. {: important}

  1. Create the database:
my_database = client.create_database(database_name)

{: codeblock}

  1. Confirm that the database was created successfully:
if my_database.exists():
    print(f"'{database_name}' successfully created.")

{: codeblock}

Step 3. Store a small collection of data as documents within the database

{: #step-3-store-a-small-collection-of-data-as-documents-within-the-database}

  1. Define a collection of data:
sample_data = [
    [1, "one", "boiling", 100],
    [2, "two", "hot", 40],
    [3, "three", "warm", 20],
    [4, "four", "cold", 10],
    [5, "five", "freezing", 0]
  ]

{: codeblock}

  1. Use Python code to "step" through the data and convert it into JSON documents. Each document is stored in the database:
# Create documents by using the sample data.
# Go through each row in the array
for document in sample_data:
  # Retrieve the fields in each row.
  number = document[0]
  name = document[1]
  description = document[2]
  temperature = document[3]
  #
  # Create a JSON document that represents
  # all the data in the row.
  json_document = {
      "numberField": number,
      "nameField": name,
      "descriptionField": description,
      "temperatureField": temperature
  }
  #
  # Create a document by using the database API.
  new_document = my_database.create_document(json_document)
  #
  # Check that the document exists in the database.
  if new_document.exists():
      print(f"Document '{number}' successfully created.")

{: codeblock}

Notice that we check to ensure that each document is successfully created. {: tip}

Step 4. Retrieve data through queries

{: #step-4-retrieve-data-through-queries}

A small collection of data was stored as documents within the database. You can do a minimal or full retrieval of that data from the database. A minimal retrieval includes the basic data about a document. A full retrieval also includes the data within a document.

  • To run a minimal retrieval, follow these steps:

    1. First, request a list of all documents within the database.
    result_collection = Result(my_database.all_docs)

    {: codeblock}

    This list is returned as an array.

    1. Display the content of an element in the array.
    print(f"Retrieved minimal document:\n{result_collection[0]}\n")

    {: codeblock}

    The result is similar to the following example:

    [{u'value': {u'rev': u'1-106e76a2612ea13468b2f243ea75c9b1'}, u'id': u'14be111aac74534cf8d390eaa57db888', u'key': u'14be111aac74534cf8d390eaa57db888'}]

    {: screen}

    The u prefix is an indication that Python is displaying a Unicode string. {: tip}

    If we tidy the appearance a little, we can see that the minimal document details returned are similar to this example.

    [
    {
        "value": {
            "rev": "1-106e76a2612ea13468b2f243ea75c9b1"
        },
        "id": "14be111aac74534cf8d390eaa57db888",
        "key": "14be111aac74534cf8d390eaa57db888"
    }
]

    {: codeblock}

    NoSQL databases like {{site.data.keyword.cloudant_short_notm}} don't always adhere to the first in first out method, which means that a document that is stored in the database isn't always the first document that is returned in a list of results. {: note}

  • To run a full retrieval, request a list of all documents within the database, and provide the include_docs option to specify that the document content must also be returned.

    result_collection = Result(my_database.all_docs, include_docs=True)
print(f"Retrieved full document:\n{result_collection[0]}\n")

    {: codeblock}

    The result is similar to the following example:

    [{u'value': {u'rev': u'1-7130413a8c7c5f1de5528fe4d373045c'}, u'id': u'0cfc7d902f613d5fdb7b7818e262353b', u'key': u'0cfc7d902f613d5fdb7b7818e262353b', u'doc': {u'temperatureField': 40, u'descriptionField': u'hot', u'numberField': 2, u'nameField': u'two', u'_id': u'0cfc7d902f613d5fdb7b7818e262353b', u'_rev': u'1-7130413a8c7c5f1de5528fe4d373045c'}}]

    {: screen}

    If we tidy the appearance a little, we can see that the full document details we got back are similar to this example.

    [
  {
    "value": {
      "rev": "1-7130413a8c7c5f1de5528fe4d373045c
    },
    "id": "0cfc7d902f613d5fdb7b7818e262353b",
    "key": "0cfc7d902f613d5fdb7b7818e262353b",
    "doc": {
      "temperatureField": 40,
      "descriptionField": "hot",
      "numberField": 2,
      "nameField": "two",
      "_id": "0cfc7d902f613d5fdb7b7818e262353b",
      "_rev": "1-7130413a8c7c5f1de5528fe4d373045c"
    }
  }
]

    {: codeblock}

(Optional) Step 5. See database information on the {{site.data.keyword.cloudant_short_notm}} Dashboard

{: #optional-step-5-ibm-cloudant-dashboard}

Follow these steps to see your database and documents on the {{site.data.keyword.cloudant_short_notm}} Dashboard.

  1. Log in to your {{site.data.keyword.cloud_notm}} account. The {{site.data.keyword.cloud_notm}} dashboard can be found at: cloud.ibm.com. After you authenticate with your user name and password, you're presented with the IBM Cloud dashboard.
  2. Click Services in the Resource summary pane to see your {{site.data.keyword.cloudant_short_notm}} service instances.
  3. Click the service instance whose details you want to see.
  4. Click Launch Cloudant Dashboard. When the dashboard opens, you can see the databases that are associated with your service.

Step 6. Delete the database

{: #step-6-delete-the-database}

When you're finished with the database, it can be deleted.

try:
    client.delete_database(database_name)
except CloudantException:
    print(f"There was a problem deleting '{database_name}'.\n")
else:
    print(f"'{database_name}' successfully deleted.\n")

{: codeblock}

We included some basic error handling to show you how to troubleshoot and address potential issues.

Step 7. Close the connection to the service instance

{: #step-7-close-the-connection-to-the-service-instance}

The final step is to disconnect the Python client application from the service instance:

client.disconnect()

{: codeblock}

Next steps

{: #next-steps}

For more information about all {{site.data.keyword.cloudant_short_notm}} offerings, see the main {{site.data.keyword.cloudant_short_notm}}{: new_window}{: external} site.

For more information, see tutorials, {{site.data.keyword.cloudant_short_notm}} concepts, tasks, and techniques in the {{site.data.keyword.cloudant_short_notm}} documentation.

Appendix. Complete Python code listing

{: #appendix-complete-python-code-listing}

The complete Python code listing is as follows. Remember to replace the <username>, <password>, <url>, and <apikey> values with your service credentials. Similarly, replace the <yourDatabaseName> value with the name for your database.

from cloudant.client import Cloudant
from cloudant.error import CloudantException
from cloudant.result import Result

# {{site.data.keyword.cloudant_short_notm}} Legacy authentication
client = Cloudant("<username>", "<password>", url="<url>")
client.connect()

# IAM Authentication (uncomment if needed, and comment out previous {{site.data.keyword.cloudant_short_notm}} Legacy authentication section)
# client = Cloudant.iam("<username>", "<apikey>")
# client.connect()

database_name = "<your-database-name>"

my_database = client.create_database(database_name)

if my_database.exists():
    print(f"'{database_name}' successfully created.")

sample_data = [
    [1, "one", "boiling", 100],
    [2, "two", "hot", 40],
    [3, "three", "warm", 20],
    [4, "four", "cold", 10],
    [5, "five", "freezing", 0]
]

# Create documents using the sample data.
# Go through each row in the array
for document in sample_data:
    # Retrieve the fields in each row.
    number = document[0]
    name = document[1]
    description = document[2]
    temperature = document[3]

    # Create a JSON document that represents
    # all the data in the row.
    json_document = {
        "numberField": number,
        "nameField": name,
        "descriptionField": description,
        "temperatureField": temperature
    }

    # Create a document using the Database API.
    new_document = my_database.create_document(json_document)

    # Check that the document exists in the database.
    if new_document.exists():
        print(f"Document '{number}' successfully created.")

result_collection = Result(my_database.all_docs)

print(f"Retrieved minimal document:\n{result_collection[0]}\n")

result_collection = Result(my_database.all_docs, include_docs=True)
print(f"Retrieved full document:\n{result_collection[0]}\n")

try:
    client.delete_database(database_name)
except CloudantException:
    print(f"There was a problem deleting '{database_name}'.\n")
else:
    print(f"'{database_name}' successfully deleted.\n")

client.disconnect()

{: codeblock}