fileblob

Documentation

Overview

Package fileblob provides a blob implementation that uses the filesystem. Use OpenBucket to construct a *blob.Bucket.

Open URLs

For blob.Open URLs, fileblob registers for the scheme "file"; URLs start with "file://" like "file:///path/to/directory". For full details, see URLOpener.

Escaping

Go CDK supports all UTF-8 strings; to make this work with providers lacking full UTF-8 support, strings must be escaped (during writes) and unescaped (during reads). The following escapes are performed for fileblob:

• Blob keys: ASCII characters 0-31 are escaped to "__0x<hex>__". If os.PathSeparator != "/", it is also escaped. Additionally, the "/" in "../", the trailing "/" in "//", and a trailing "/" is key names are escaped in the same way.

As

fileblob exposes the following types for As:

• Error: *os.PathError

Example

package main

import (
	"context"
	"fmt"
	"io/ioutil"
	"log"
	"os"

	"gocloud.dev/blob/fileblob"
)

func main() {

	// Create a temporary directory.
	dir, err := ioutil.TempDir("", "go-cloud-fileblob-example")
	if err != nil {
		log.Fatal(err)
	}
	defer os.RemoveAll(dir)

	// Create a file-based bucket.
	b, err := fileblob.OpenBucket(dir, nil)
	if err != nil {
		log.Fatal(err)
	}

	// Now we can use b to read or write files to the container.
	ctx := context.Background()
	err = b.WriteAll(ctx, "my-key", []byte("hello world"), nil)
	if err != nil {
		log.Fatal(err)
	}
	data, err := b.ReadAll(ctx, "my-key")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(data))

}

Output:

hello world

Example (Open)

package main

import (
	"context"
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"path"

	"gocloud.dev/blob"
)

func main() {
	// Create a temporary directory.
	dir, err := ioutil.TempDir("", "go-cloud-fileblob-example")
	if err != nil {
		log.Fatal(err)
	}
	defer os.RemoveAll(dir)

	// Open creates a *blob.Bucket from a URL.
	ctx := context.Background()
	b, err := blob.OpenBucket(ctx, path.Join("file://", dir))
	if err != nil {
		log.Fatal(err)
	}

	// Now we can use b to read or write files to the container.
	err = b.WriteAll(ctx, "my-key", []byte("hello world"), nil)
	if err != nil {
		log.Fatal(err)
	}
	data, err := b.ReadAll(ctx, "my-key")
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(string(data))

}

Output:

hello world

Index

• Constants
• func OpenBucket(dir string, opts *Options) (*blob.Bucket, error)
• type Options
• type URLOpener
  • func (*URLOpener) OpenBucketURL(ctx context.Context, u *url.URL) (*blob.Bucket, error)

Examples

• Package
• Package (Open)

Constants

const Scheme = "file"

Scheme is the URL scheme fileblob registers its URLOpener under on blob.DefaultMux.

Functions

func OpenBucket

func OpenBucket(dir string, opts *Options) (*blob.Bucket, error)

OpenBucket creates a *blob.Bucket backed by the filesystem and rooted at dir, which must exist. See the package documentation for an example.

Types

type Options

type Options struct{}

Options sets options for constructing a *blob.Bucket backed by fileblob.

type URLOpener

type URLOpener struct{}

URLOpener opens file bucket URLs like "file:///foo/bar/baz".

func (*URLOpener) OpenBucketURL

func (*URLOpener) OpenBucketURL(ctx context.Context, u *url.URL) (*blob.Bucket, error)

OpenBucketURL opens the file bucket at the URL's path. The URL's host is ignored. If os.PathSeparator != "/", any leading "/" from the path is dropped and remaining '/' characters are converted to os.PathSeparator. No query options are supported. Examples:

• file:///a/directory -> Passes "/a/directory" to OpenBucket.
• file://localhost/a/directory -> Also passes "/a/directory".
• file:///c:/foo/bar -> Passes "c:\foo\bar".
• file://localhost/c:/foo/bar -> Also passes "c:\foo\bar".