Filestack Go

This is the official Go SDK for Filestack - API and content management system that makes it easy to add powerful file uploading and transformation capabilities to any web or mobile application.

Resources

To learn more about this SDK, please visit our API Reference

Install

Install the package with:

go get github.com/filestack/filestack-go

Import it with:

import "github.com/filestack/filestack-go"

Quickstart

The Filestack SDK allows you to upload files, perform transformations and handle filelinks.

The Client

For most features provided by this SDK you will need a Client instance. It can be initialized with the following statement:

client.NewClient(yourApiKey)

The most basic use case:

package main

import (
	"fmt"
	"log"

	"github.com/filestack/filestack-go/client"
)

func main() {
	cli, err := client.NewClient(yourApiKey)
	if err != nil {
		log.Fatalf("failed to initialize client: %v", err)
	}
	fileLink := cli.MustNewFileLink(yourHandle)
	fmt.Print(fileLink.AsString())
}

Often you will need to adjust settings to your needs. NewClient constructor accepts optional arguments. For example if your account has enabled security, you will need to add an optional argument like here:

package main

import (
	"fmt"
	"log"
	"time"

	"github.com/filestack/filestack-go/client"
	clientOptions "github.com/filestack/filestack-go/options/client"
	"github.com/filestack/filestack-go/security"
)

func main() {
	sec := security.NewSecurity(YourSecret, &security.Policy{
		Expiry: time.Now().Add(time.Duration(24 * time.Hour)).Unix(), // the only required parameter
	})
	cli, err := client.NewClient(YourApiKey, clientOptions.SecurityPolicy(sec))
	if err != nil {
		log.Fatalf("failed to initialize the client: %v", err)
	}

	fileLink := cli.MustNewFileLink(YourHandle)
	fmt.Print(fileLink.AsString())
}

Overwrite the default http client

API requests are handled by RequestHandler service. It uses an instance of http.Client by default.
To fulfill your requirements, a custom client can be injected using options:

package main

import (
	"fmt"
	"log"
	"net/http"
	"time"

	"github.com/filestack/filestack-go/client"
	clientOptions "github.com/filestack/filestack-go/options/client"
)

func main() {
	httpClient := &http.Client{
		Timeout: time.Minute,
	}

	cli, err := client.NewClient(yourApiKey, clientOptions.HTTPClient(httpClient))
	if err != nil {
		log.Fatalf("failed to initialize client: %v", err)
	}
	fileLink := cli.MustNewFileLink(yourHandle)
	fmt.Print(fileLink.AsString())
}

Uploads

One of the basic features of this SDK are uploads.
The following example shows the easiest way to upload a file.

package main

import (
	"context"
	"fmt"
	"log"
	"os"

	"github.com/filestack/filestack-go/client"
)

func main() {
	file, err := os.Open(yourFilePath)
	if err != nil {
		log.Fatal("cannot read the file")
	}
	defer file.Close()

	cli, err := client.NewClient(yourApiKey)
	if err != nil {
		log.Fatalf("failed to initialize client: %v", err)
	}
	fileLink, err := cli.Upload(context.Background(), file)
	if err != nil {
		log.Fatalf("error: %v", err)
	}

	fmt.Println(fileLink.AsString())
}

Upload URL

When you are dealing with external files, UploadURL method can be used:

package main

import (
	"context"
	"fmt"
	"log"

	"github.com/filestack/filestack-go/client"
)

func main() {
	cli, err := client.NewClient(yourApiKey)
	if err != nil {
		log.Fatalf("failed to initialize the client: %v", err)
	}

	fileLink, err := cli.UploadURL(context.Background(), yourURL)
	if err != nil {
		log.Fatalf("error: %v", err)
	}

	fmt.Println(fileLink.AsString())
}

Transformations

You can perform a number of transformations on your files. The source files for transformations are called resources and they can be one of:

• external url
• handle
• storage alias

Most of the transformations work in a context of a single resource, but there are exceptions where more than one file reference is required.

Resources

For a handle string, you can create a new transformation with:

cli.MustNewTransformation(resource.NewHandle(yourHandle))

For an external URL use:

cli.MustNewTransformation(resource.NewExternalURL(yourExternalURL))

And for storage aliases use:

cli.MustNewTransformation(resource.NewStorageAlias(yourAlias, yourPath))

Performing transformations

package main

import (
	"fmt"

	"github.com/filestack/filestack-go/client"
	"github.com/filestack/filestack-go/resource"
)

func main() {
	cli := client.NewClient(yourApiKey)
	transformation := cli.MustNewTransformation(resource.NewExternalURL("https://www.google.com/image.jpg"))
	transformation.Flip() // or any other image transformation

	fmt.Println(transformation.BuildURL())
}

Transformations can be chained, since the API provides possibility to apply multiple tasks at once. For example:

transformation.Flip().Negative() // more than one transformation task at once

Transformation tasks can have optional parameters. For example Resize needs width, height or both dimensions together. Therefore majority of transformation methods expect Args as a parameter. This dedicated type wraps all parameters and provides setters for ease of use. Each method has its corresponding Args type and can be initialized with a constructor, as in the following example:

transformation.Upscale(args.NewUpscaleArgs().SetNoise("low"))

transformation.BlackWhite(args.NewBlackWhiteArgs().SetThreshold(5))

Workflows

Workflows allow you to perform a sequence of tasks and include a conditional logic.
They can be defined on your account. You refer to a workflow by its unique identifier.
More information about the concept of workflows can be found here: https://www.filestack.com/docs/workflows/overview/

The following example shows how to schedule a job:

externalURL := resource.NewExternalURL(yourImageURL)
workflow := client.NewWorkflow()
response, err := workflow.Run(context.Background(), yourWorkflowsId, externalURL)
if err != nil {
    // handle error
}
fmt.Printf("job id = %s", response.JobID)

The workflow type provides Run and Status methods. Workflows processing is asynchronous, therefore you don't get an instant result upong running it. You get a JobID instead and based on that value, you can check the processing status:

response, err := workflow.Status(context.Background(), workflowJobID)
if err != nil {
    // handle error
}
fmt.Println(response.Results)