126 lines
3.3 KiB
Markdown
126 lines
3.3 KiB
Markdown
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go-cid
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==================
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[](http://ipn.io)
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[](http://ipfs.io/)
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[](http://webchat.freenode.net/?channels=%23ipfs)
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[](https://github.com/RichardLitt/standard-readme)
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[](https://godoc.org/github.com/ipfs/go-cid)
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[](https://coveralls.io/github/ipfs/go-cid?branch=master)
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[](https://travis-ci.org/ipfs/go-cid)
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> A package to handle content IDs in Go.
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This is an implementation in Go of the [CID spec](https://github.com/ipld/cid).
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It is used in `go-ipfs` and related packages to refer to a typed hunk of data.
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## Table of Contents
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- [Install](#install)
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- [Usage](#usage)
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- [API](#api)
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- [Contribute](#contribute)
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- [License](#license)
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## Install
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`go-cid` is a standard Go module which can be installed with:
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```sh
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go get github.com/ipfs/go-cid
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```
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Note that `go-cid` is packaged with Gx, so it is recommended to use Gx to install and use it (see Usage section).
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## Usage
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### Using Gx and Gx-go
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This module is packaged with [Gx](https://github.com/whyrusleeping/gx). In order to use it in your own project it is recommended that you:
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```sh
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go get -u github.com/whyrusleeping/gx
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go get -u github.com/whyrusleeping/gx-go
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cd <your-project-repository>
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gx init
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gx import github.com/ipfs/go-cid
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gx install --global
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gx-go --rewrite
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```
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Please check [Gx](https://github.com/whyrusleeping/gx) and [Gx-go](https://github.com/whyrusleeping/gx-go) documentation for more information.
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### Running tests
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Before running tests, please run:
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```sh
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make deps
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```
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This will make sure that dependencies are rewritten to known working versions.
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### Examples
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#### Parsing string input from users
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```go
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// Create a cid from a marshaled string
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c, err := cid.Decode("bafzbeigai3eoy2ccc7ybwjfz5r3rdxqrinwi4rwytly24tdbh6yk7zslrm")
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if err != nil {...}
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fmt.Println("Got CID: ", c)
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```
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#### Creating a CID from scratch
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```go
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// Create a cid manually by specifying the 'prefix' parameters
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pref := cid.Prefix{
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Version: 1,
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Codec: cid.Raw,
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MhType: mh.SHA2_256,
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MhLength: -1, // default length
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}
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// And then feed it some data
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c, err := pref.Sum([]byte("Hello World!"))
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if err != nil {...}
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fmt.Println("Created CID: ", c)
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```
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#### Check if two CIDs match
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```go
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// To test if two cid's are equivalent, be sure to use the 'Equals' method:
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if c1.Equals(c2) {
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fmt.Println("These two refer to the same exact data!")
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}
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```
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#### Check if some data matches a given CID
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```go
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// To check if some data matches a given cid,
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// Get your CIDs prefix, and use that to sum the data in question:
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other, err := c.Prefix().Sum(mydata)
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if err != nil {...}
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if !c.Equals(other) {
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fmt.Println("This data is different.")
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}
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```
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## Contribute
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PRs are welcome!
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Small note: If editing the Readme, please conform to the [standard-readme](https://github.com/RichardLitt/standard-readme) specification.
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## License
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MIT © Jeromy Johnson
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