cloudant-go-sdk

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IBM Cloudant Go SDK Version 0.4.2

IBM Cloudant Go SDK is a client library that interacts with the IBM Cloudant APIs.

Disclaimer: This library is still a 0.x release. We do consider this library production-ready and capable, but there are still some limitations we’re working to resolve, and refinements we want to deliver. We are working really hard to minimise the disruption from now until the 1.0 release, but there may still be some changes that impact applications using this SDK. For now, be sure to pin versions to avoid surprises.

Table of Contents

Overview

The IBM Cloudant Go SDK allows developers to programmatically interact with IBM Cloudant with the help of the cloudantv1 package.

Features

The purpose of this Go SDK is to wrap most of the HTTP request APIs provided by Cloudant and supply other functions to ease the usage of Cloudant. This SDK should make life easier for programmers to do what’s really important to them: developing software.

Reasons why you should consider using Cloudant Go SDK in your project:

  • Supported by IBM Cloudant.
  • Server compatibility with:
  • Includes all the most popular and latest supported endpoints for applications.
  • Handles the authentication.
  • Familiar user experience with IBM Cloud SDKs.
  • Flexibility to use either built-in models or byte-based requests and responses for documents.
  • HTTP2 support for higher performance connections to IBM Cloudant.
  • Perform requests synchronously.
  • Safe for concurrent use by multiple goroutines.
  • Transparently compresses request and response bodies.

Prerequisites

  • A Cloudant service instance or a CouchDB server.
  • Go version 1.19 or 1.20.

Installation

The current version of this SDK: 0.4.2

There are a few different ways to download and add the Cloudant Go SDK project for use by your Go application:

go get command

Use this command to download and add the SDK to allow your Go application to use it:

go get -u github.com/IBM/cloudant-go-sdk/cloudantv1@v0.4.2
Go modules

If your application is using Go modules, you can add a suitable import to your Go application, like this:

import (
  "github.com/IBM/cloudant-go-sdk/cloudantv1"
)

then run go mod tidy to download and install the latest version if the dependency is missing. This command will also update your Go application's go.mod file.

Authentication

This library requires some of your Cloudant service credentials to authenticate with your account.

  1. IAM, COUCHDB_SESSION, BASIC or NOAUTH authentication type.
    1. IAM authentication is highly recommended when your back-end database server is Cloudant. This authentication type requires a server-generated apikey instead of a user-given password. You can create one here.
    2. Session cookie (COUCHDB_SESSION) authentication is recommended for Apache CouchDB or for Cloudant when IAM is unavailable. It exchanges username and password credentials for an AuthSession cookie from the /_session endpoint.
    3. Basic (or legacy) authentication is a fallback for both Cloudant and Apache CouchDB back-end database servers. This authentication type requires the good old username and password credentials.
    4. Noauth authentication does not require credentials. Note that this authentication type only works with queries against a database with read access for everyone.
  2. The service url.

There are several ways to set these properties:

  1. As environment variables
  2. The programmatic approach
  3. With an external credentials file
Authentication with environment variables
IAM authentication

For Cloudant IAM authentication, set the following environmental variables by replacing the <url> and <apikey> with your proper service credentials. There is no need to set CLOUDANT_AUTH_TYPE to IAM because it is the default.

CLOUDANT_URL=<url>
CLOUDANT_APIKEY=<apikey>

For COUCHDB_SESSION authentication, set the following environmental variables by replacing the <url>, <username> and <password> with your proper service credentials.

CLOUDANT_AUTH_TYPE=COUCHDB_SESSION
CLOUDANT_URL=<url>
CLOUDANT_USERNAME=<username>
CLOUDANT_PASSWORD=<password>
Basic authentication

For Basic authentication, set the following environmental variables by replacing the <url>, <username> and <password> with your proper service credentials.

CLOUDANT_AUTH_TYPE=BASIC
CLOUDANT_URL=<url>
CLOUDANT_USERNAME=<username>
CLOUDANT_PASSWORD=<password>

Note: There are also additional Bearer token, Container and VPC Instance authentication methods. For more details, please follow the provided links. We recommend that you use IAM for Cloudant and Session for CouchDB authentication.

Authentication with external configuration

To use an external configuration file, the Cloudant API docs, or the general SDK usage information will guide you.

Programmatic authentication

To learn more about how to use programmatic authentication, see the related documentation in the Cloudant API docs or in the Go SDK Core document about authentication.

Using the SDK

For fundamental SDK usage information and config options, please see the common IBM Cloud SDK documentation.

Request timeout configuration

A 6m request timeout, which includes a 30s connect timeout, is set by default. Note that this also affects changes feed requests, regardless of a timeout set on PostChangesOptions. Be sure to set a request timeout appropriate to your application usage and environment. The request timeout section contains details on how to change the value.

Note: System settings may take precedence over configured timeout values.

Code examples

The following code examples authenticate with the environment variables.

1. Create a database and add a document

Note: This example code assumes that orders database does not exist in your account.

This example code creates orders database and adds a new document "example" into it. To connect, you must set your environment variables with the service url, authentication type and authentication credentials of your Cloudant service.

Cloudant environment variable naming starts with a service name prefix that identifies your service. By default, this is CLOUDANT, see the settings in the authentication with environment variables section.

If you would like to rename your Cloudant service from CLOUDANT, you must use your defined service name as the prefix for all Cloudant related environment variables.

Once the environment variables are set, you can try out the code examples.

package main

import (
	"encoding/json"
	"fmt"

	"github.com/IBM/cloudant-go-sdk/cloudantv1"
)

func main() {
	// 1. Create a client with `CLOUDANT` default service name =============
	client, err := cloudantv1.NewCloudantV1UsingExternalConfig(
		&cloudantv1.CloudantV1Options{},
	)
	if err != nil {
		panic(err)
	}

	// 2. Create a database ================================================
	exampleDbName := "orders"

	putDatabaseResult, putDatabaseResponse, err := client.PutDatabase(
		client.NewPutDatabaseOptions(exampleDbName),
	)
	if err != nil {
		if putDatabaseResponse.StatusCode == 412 {
			fmt.Printf("Cannot create \"%s\" database, it already exists.\n",
				exampleDbName)
		} else {
			panic(err)
		}
	}

	if putDatabaseResult != nil && *putDatabaseResult.Ok {
		fmt.Printf("\"%s\" database created.\n", exampleDbName)
	}

	// 3. Create a document ================================================
	// Create a document object with "example" id
	exampleDocID := "example"
	// Setting ID for the document is optional when "PostDocument" function
	// is used for CREATE.
	// When ID is not provided the server will generate one for your document.
	exampleDocument := cloudantv1.Document{
		ID: &exampleDocID,
	}

	// Add "name" and "joined" fields to the document
	exampleDocument.SetProperty("name", "Bob Smith")
	exampleDocument.SetProperty("joined", "2019-01-24T10:42:59.000Z")

	// Save the document in the database with "PostDocument" function
	createDocumentOptions := client.NewPostDocumentOptions(
		exampleDbName,
	).SetDocument(&exampleDocument)

	createDocumentResponse, _, err := client.PostDocument(createDocumentOptions)

	// =====================================================================
	// Note: saving the document can also be done with the "PutDocument"
	// function. In this case docID is required for a CREATE operation:
	/*
		createDocumentOptions := client.NewPutDocumentOptions(
			exampleDbName,
			exampleDocID,
		).SetDocument(&exampleDocument)

		createDocumentResponse, _, err := client.PutDocument(createDocumentOptions)
	*/
	// =====================================================================

	if err != nil {
		panic(err)
	}

	// Keeping track of the revision number of the document object
	// is necessary for further UPDATE/DELETE operations:
	exampleDocument.Rev = createDocumentResponse.Rev

	// Print out the document content
	exampleDocumentContent, _ := json.MarshalIndent(exampleDocument, "", "  ")
	fmt.Printf("You have created the document:\n%s\n", string(exampleDocumentContent))
}

When you run the code, you see a result similar to the following output.

"orders" database created.
You have created the document:
{
  "_id": "example",
  "_rev": "1-1b403633540686aa32d013fda9041a5d",
  "joined": "2019-01-24T10:42:99.000Z",
  "name": "Bob Smith"
}
2. Retrieve information from an existing database

Note: This example code assumes that you have created both the orders database and the example document by running the previous example code successfully. Otherwise, the following error message occurs, "Cannot delete document because either 'orders' database or 'example' document was not found."

Gather database information example 
package main

import (
	"encoding/json"
	"fmt"

	"github.com/IBM/cloudant-go-sdk/cloudantv1"
)

func main() {
	// 1. Create a client with `CLOUDANT` default service name ============
	client, err := cloudantv1.NewCloudantV1UsingExternalConfig(
		&cloudantv1.CloudantV1Options{},
	)
	if err != nil {
		panic(err)
	}
	// 2. Get server information ===========================================
	serverInformationResult, _, err := client.GetServerInformation(
		client.NewGetServerInformationOptions(),
	)
	if err != nil {
		panic(err)
	}
	fmt.Printf("Server Version: %s\n", *serverInformationResult.Version)
	// 3. Get database information for "orders" ==========================
	dbName := "orders"
	databaseInformationResult, _, err := client.GetDatabaseInformation(
		client.NewGetDatabaseInformationOptions(
			dbName,
		),
	)
	if err != nil {
		panic(err)
	}
	// 4. Show document count in database ==================================
	fmt.Printf("Document count in \"%s\" database is %d.\n",
		*databaseInformationResult.DbName,
		*databaseInformationResult.DocCount)
	// 5. Get "example" document out of the database by document id ============
	documentExampleResult, _, err := client.GetDocument(
		client.NewGetDocumentOptions(
			dbName,
			"example",
		),
	)
	if err != nil {
		panic(err)
	}
	// 6. Print out the Document content ===================================
	exampleBuffer, _ := json.MarshalIndent(documentExampleResult, "", "  ")
	fmt.Println(string(exampleBuffer))
}
When you run the code, you see a result similar to the following output. 
Server Version: 2.1.1
Document count in "orders" database is 1.
{
  "_id": "example",
  "_rev": "1-1b403633540686aa32d013fda9041a5d",
  "name": "Bob Smith",
  "joined": "2019-01-24T10:42:99.000Z"
}
3. Update your previously created document

Note: This example code assumes that you have created both the orders database and the example document by running the previous example code successfully. Otherwise, the following error message occurs, "Cannot update document because either 'orders' database or 'example' document was not found."

Update code example 
package main

import (
	"encoding/json"
	"fmt"

	"github.com/IBM/cloudant-go-sdk/cloudantv1"
)

func main() {
	// 1. Create a client with `CLOUDANT` default service name =============
	client, err := cloudantv1.NewCloudantV1UsingExternalConfig(
		&cloudantv1.CloudantV1Options{},
	)
	if err != nil {
		panic(err)
	}

	// 2. Update the document ==============================================
	exampleDbName := "orders"
	exampleDocID := "example"

	// Get the document if it previously existed in the database
	document, getDocumentResponse, err := client.GetDocument(
		client.NewGetDocumentOptions(
			exampleDbName,
			exampleDocID,
		),
	)

	// =====================================================================
	// Note: for response byte stream use:
	/*
		documentAsByteStream, getDocumentResponse, err := client.GetDocumentAsStream(
			client.NewGetDocumentOptions(
				exampleDbName,
				exampleDocID,
			),
		)
	*/
	// =====================================================================

	if err != nil {
		if getDocumentResponse.StatusCode == 404 {
			fmt.Printf("Cannot update document because "+
				"either \"%s\"  database or \"%s\" document was not found.\n",
				exampleDbName,
				exampleDocID)
		} else {
			panic(err)
		}
	}

	if document != nil {
		// Make some modification in the document content
		// Add Bob Smith's address to the document
		document.SetProperty("address", "19 Front Street, Darlington, DL5 1TY")
		// Remove the joined property from document object
		delete(document.GetProperties(), "joined")

		// Update the document in the database
		updateDocumentOptions := client.NewPostDocumentOptions(
			exampleDbName,
		).SetDocument(document)

		// =================================================================
		// Note: for request byte stream use:
		/*
			postDocumentOption := client.NewPostDocumentOptions(
				exampleDbName,
			).SetBody(documentAsByteStream)
		*/
		// =================================================================

		updateDocumentResponse, _, err := client.PostDocument(
			updateDocumentOptions,
		)

		// =================================================================
		// Note: updating the document can also be done with the "PutDocument"
		// function. DocID and Rev are required for an UPDATE operation
		// but Rev can be provided in the document object too:
		/*
			updateDocumentOptions := client.NewPutDocumentOptions(
				exampleDbName,
				core.StringNilMapper(document.ID), // docID is a required parameter
			).SetDocument(document) // Rev in the document object CAN replace below SetRev

			updateDocumentOptions.SetRev(core.StringNilMapper(document.Rev))

			updateDocumentResponse, _, err := client.PutDocument(
				updateDocumentOptions,
			)
		*/
		// =================================================================

		if err != nil {
			panic(err)
		}

		// Keeping track of the latest revision number of the document object
		// is necessary for further UPDATE/DELETE operations:
		document.Rev = updateDocumentResponse.Rev

		// Print out the new document content
		documentContent, _ := json.MarshalIndent(document, "", "  ")
		fmt.Printf("You have updated the document:\n%s\n", string(documentContent))
	}
}
When you run the code, you see a result similar to the following output. 
You have updated the document:
{
  "_id": "example",
  "_rev": "2-4e2178e85cffb32d38ba4e451f6ca376",
  "address": "19 Front Street, Darlington, DL5 1TY",
  "name": "Bob Smith"
}
4. Delete your previously created document

Note: This example code assumes that you have created both the orders database and the example document by running the previous example code successfully. Otherwise, the following error message occurs, "Cannot delete document because either 'orders' database or 'example' document was not found."

Delete code example 
package main

import (
	"fmt"

	"github.com/IBM/cloudant-go-sdk/cloudantv1"
)

func main() {

	// 1. Create a client with `CLOUDANT` default service name =============
	client, err := cloudantv1.NewCloudantV1UsingExternalConfig(
		&cloudantv1.CloudantV1Options{},
	)
	if err != nil {
		panic(err)
	}

	// 2. Delete the document ==============================================
	exampleDbName := "orders"
	exampleDocID := "example"

	// 2.1. Get the document if it previously existed in the database
	document, getDocumentResponse, err := client.GetDocument(
		client.NewGetDocumentOptions(
			exampleDbName,
			exampleDocID,
		),
	)
	if err != nil {
		if getDocumentResponse.StatusCode == 404 {
			fmt.Printf("Cannot delete document because "+
				"either \"%s\" database or \"%s\" document was not found.\n",
				exampleDbName,
				exampleDocID)
		} else {
			panic(err)
		}
	}
	// 2.2. Use its latest revision to delete
	if document != nil {
		deleteDocumentResult, _, err := client.DeleteDocument(
			client.NewDeleteDocumentOptions(
				exampleDbName,
				*document.ID, // docID is required for DELETE
			).SetRev(*document.Rev), // Rev is required for DELETE
		)
		if err != nil {
			panic(err)
		}

		if *deleteDocumentResult.Ok {
			fmt.Println("You have deleted the document.")
		}
	}
}
When you run the code, you see the following output. 
You have deleted the document.
Further code examples

For a complete list of code examples, see the examples directory.

Error handling

For sample code on handling errors, see Cloudant API docs.

Raw IO

For endpoints that read or write document content it is possible to bypass usage of the built-in struct with byte streams.

Depending on the specific SDK operation it may be possible to:

  • accept a user-provided byte stream to send to the server as a request body
  • return a byte stream of the server response body to the user

Request byte stream can be supplied for method options that have a Body property. For these cases you can pass this byte stream directly to the HTTP request body.

Response byte stream is supported in functions with the suffix of AsStream. The returned byte stream allows the response body to be consumed without triggering JSON unmarshalling that is typically performed by the SDK.

The update document section contains examples for both request and response byte stream cases.

The API reference contains further examples of using byte streams. They are titled "Example request as stream" and are initially collapsed. Expand them to see examples of:

Further resources
  • Cloudant API docs: API reference including usage examples for Cloudant Go SDK API.
  • Godoc: Cloudant Go SDK API Documentation.
  • Cloudant docs: The official documentation page for Cloudant.
  • Cloudant blog: Many useful articles about how to optimize Cloudant for common problems.

Questions

If you are having difficulties using this SDK or have a question about the IBM Cloud services, ask a question on Stack Overflow.

Issues

If you encounter an issue with the project, you are welcome to submit a bug report.

Before you submit a bug report, search for similar issues and review the KNOWN_ISSUES file to verify that your issue hasn't been reported yet.

Please consult the security policy before opening security related issues.

Open source at IBM

Find more open source projects on the IBM GitHub page.

Contributing

For more information, see CONTRIBUTING.

License

This SDK is released under the Apache 2.0 license. To read the full text of the license, see LICENSE.

Directories

Path Synopsis
Package cloudantv1 : Operations and models for the CloudantV1 service
 Package cloudantv1 : Operations and models for the CloudantV1 service
test
examples/src/create_db_and_doc
examples/src/delete_doc
examples/src/get_info_from_existing_database
examples/src/update_doc

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