An easy way to buy, send, and accept bitcoin through the Coinbase API.
This library supports both the API key authentication method and OAuth. The below examples use an API key - for instructions on how to use OAuth, see OAuth Authentication.
A detailed step-by-step tutorial on how to use this library can be found at this blog.
Make sure you have set the environment variable $GOPATH
export GOPATH="path/to/your/go/folder"Obtain the latest version of the Coinbase Go library with:
go get github.com/fabioberger/coinbase-goThen, add the following to your Go project:
import (
"github.com/fabioberger/coinbase-go"
)Start by enabling an API Key on your account.
Next, create an instance of the client using the ApiKeyClient method:
c := coinbase.ApiKeyClient(os.Getenv("COINBASE_KEY"), os.Getenv("COINBASE_SECRET"))Notice here that we did not hard code the API key into our codebase, but set it in an environment variable instead. This is just one example, but keeping your credentials separate from your code base is a good security practice. Here is a step-by-step guide on how to add these environment variables to your shell config file.
Now you can call methods on c similar to the ones described in the API reference. For example:
balance, err := c.GetBalance()
if err != nil {
log.Fatal(err)
}
fmt.Printf("Balance is %f BTC", balance)A working API key example is available in example/ApiKeyExample.go. To run it, execute:
go run ./example/ApiKeyExample.go
All errors generated at runtime will be returned to the calling client method. Any API request for which Coinbase returns an error encoded in a JSON response will be parsed and returned by the client method as a Golang error struct. Lastly, it is important to note that for HTTP requests, if the response code returned is not '200 OK', an error will be returned to the client method detailing the response code that was received.
user, err := c.GetUser()
if err != nil {
log.Fatal(err)
}
fmt.Println(user.Name)
// 'User One'
fmt.Println(user.Email)
// '[email protected]'amount, err := c.GetBalance()
if err != nil {
log.Fatal(err)
}
fmt.Printf("Balance is %f BTC", amount)
// 'Balance is 24.229801 BTC'func (c Client) SendMoney(params *TransactionParams) (*transactionConfirmation, error)
params := &coinbase.TransactionParams{
To: "1HHNtsSVWuJXzTZrAmq71busSKLHzgm4Wb",
Amount: "0.0026",
Notes: "Thanks for the coffee!",
}
confirmation, err := c.SendMoney(params)
if err != nil {
log.Fatal(err)
}
fmt.Println(confirmation.Transaction.Status)
// 'pending'
fmt.Println(confirmation.Transaction.Id)
// '518d8567ed3ddcd4fd000034'The "To" parameter can also be a bitcoin address and the "Notes" parameter can be a note or description of the transaction. Descriptions are only visible on Coinbase (not on the general bitcoin network).
You can also send money in a number of currencies (see GetCurrencies()). The amount will be automatically converted to the correct BTC amount using the current exchange rate.
All possible transaction parameters are detailed below:
type TransactionParams struct {
To string
From string
Amount string
AmountString string
AmountCurrencyIso string
Notes string
UserFee string
ReferrerId string
Idem string
InstantBuy bool
OrderId string
}Note that parameters are equivalent to those of the coinbase API except in camelcase rather then with underscores between words (Golang standard). This can also be assumed for accessing return values. For detailed information on each parameter, check out the 'send_money' documentation
This will send an email to the recipient, requesting payment, and give them an easy way to pay.
params := &coinbase.TransactionParams{
From: "[email protected]", //Who are you requesting Bitcoins from
Amount: "2.5",
Notes: "contractor hours in January (website redesign for 50 BTC)",
}
confirmation, err := c.RequestMoney(params)
if err != nil {
log.Fatal(err)
}
fmt.Println(confirmation.Transaction.Request)
// 'true'
fmt.Println(confirmation.Transaction.Id)
// '518d8567ed3ddcd4fd000034'
success, err := c.ResendRequest("501a3554f8182b2754000003")
if err != nil {
log.Fatal(err)
}
fmt.Println(success)
// 'true'
success, err := c.CancelRequest("501a3554f8182b2754000003")
if err != nil {
log.Fatal(err)
}
fmt.Println(success)
// 'true'
// From the other account:
success, err := c.CompleteRequest("501a3554f8182b2754000003")
if err != nil {
log.Fatal(err)
}
fmt.Println(success)
// 'true'Sorted in descending order by timestamp, 30 per page. You can pass an integer as the first param to page through results, for example c.GetTransactions(2) would grab the second page.
response, err := c.GetTransactions(1)
if err != nil {
log.Fatal(err)
}
fmt.Println(response.CurrentPage)
// '1'
fmt.Println(response.NumPages)
// '2'
fmt.Println(response.Transactions[0].Id)
// '5018f833f8182b129c00002f'Transactions will always have an id attribute which is the primary way to identity them through the Coinbase api. They will also have a hsh (bitcoin hash) attribute once they've been broadcast to the network (usually within a few seconds).
Check the buy or sell price by passing a quantity of bitcoin that you'd like to buy or sell. The price can be given with or without the Coinbase's fee of 1% and the bank transfer fee of $0.15.
price, err := c.GetBuyPrice(1)
if err != nil {
log.Fatal(err)
}
fmt.Println(price.Subtotal.Amount) // Subtotal does not include fees
// '303.00'
fmt.Println(price.Total.Amount) // Total includes coinbase & bank fee
// '306.18'
price, err = c.GetSellPrice(1)
if err != nil {
log.Fatal(err)
}
fmt.Println(price.Subtotal.Amount) // Subtotal is current market price
// '9.90'
fmt.Println(price.Total.Amount) // Total is amount you will receive (after fees)
// '9.65'Buying and selling bitcoin requires you to link and verify a bank account through the web interface first.
Then you can call buy or sell and pass a quantity of bitcoin you want to buy.
On a buy, coinbase will debit your bank account and the bitcoin will arrive in your Coinbase account four business days later (this is shown as the payoutDate below). This is how long it takes for the bank transfer to complete and verify, although they are working on shortening this window. In some cases, they may not be able to guarantee a price, and buy requests will fail. In that case, set the second parameter (agreeBtcAmountVaries) to true in order to purchase bitcoin at the future market price when your money arrives.
On a sell they will credit your bank account in a similar way and it will arrive within two business days.
func (c Client) Buy(amount float64, agreeBtcAmountVaries bool) (*transfer, error)
transfer, err := c.Buy(1.0, true)
if err != nil {
log.Fatal(err)
}
fmt.Println(transfer.Code)
// '6H7GYLXZ'
fmt.Println(transfer.Btc.Amount)
// '1.00000000'
fmt.Println(transfer.Total.Amount)
// '$361.55'
fmt.Println(transfer.PayoutDate)
// '2013-02-01T18:00:00-08:00' (ISO 8601 format - can be parsed with time.Parse(transfer.PayoutDate, "2013-06-05T14:10:43.678Z"))transfer, err := c.Sell(1.0, true)
if err != nil {
log.Fatal(err)
}
fmt.Println(transfer.Code)
// '6H7GYLXZ'
fmt.Println(transfer.Btc.Amount)
// '1.00000000'
fmt.Println(transfer.Total.Amount)
// '$361.55'
fmt.Println(transfer.PayoutDate)
// '2013-02-01T18:00:00-08:00' (ISO 8601 format - can be parsed with time.Parse(transfer.PayoutDate, "2013-06-05T14:10:43.678Z"))This will create the code for a payment button (and modal window) that you can use to accept bitcoin on your website. You can read more about payment buttons here and try a demo.
The allowed ButtonParams are:
type Button struct {
Name string
PriceString string
PriceCurrencyIso string
Type string
Subscription bool
Repeat string
Style string
Text string
Description string
Custom string
CustomSecure bool
CallbackUrl string
SuccessUrl string
CancelUrl string
InfoUrl string
AutoRedirect bool
AutoRedirectSuccess bool
AutoRedirectCancel bool
VariablePrice bool
ChoosePrice bool
IncludeAddress bool
IncludeEmail bool
Price1 string
Price2 string
Price3 string
Price4 string
Price5 string
}The custom param will get passed through in callbacks to your site. The list of valid options are described here.
For detailed information on each parameter, check out the 'buttons' documentation
params := &coinbase.Button{
Name: "test",
Type: "buy_now",
Subscription: false,
PriceString: "1.23",
PriceCurrencyIso: "USD",
Custom: "Order123",
CallbackUrl: "http://www.example.com/my_custom_button_callback",
Description: "Sample Description",
Style: "custom_large",
IncludeEmail: true,
}
button, err := c.CreateButton(params)
if err != nil {
log.Fatal(err)
}
fmt.Println(button.Code)
// '93865b9cae83706ae59220c013bc0afd'
fmt.Println(button.EmbedHtml)
// '<div class=\"coinbase-button\" data-code=\"93865b9cae83706ae59220c013bc0afd\"></div><script src=\"https://coinbase.com/assets/button.js\" type=\"text/javascript\"></script>'You can fetch a list of all supported currencies and ISO codes with the GetCurrencies() method.
currencies, err := c.GetCurrencies()
if err != nil {
log.Fatal()
}
fmt.Println(currencies[0].Name)
// 'Afghan Afghani (AFN)'GetExchangeRates() will return a list of exchange rates.
exchanges, err := c.GetExchangeRates()
if err != nil {
log.Fatal(err)
}
fmt.Println(exchanges["btc_to_cad"])
// '117.13892'GetExchangeRate(from string, to string) will return a single exchange rate
exchange, err := c.GetExchangeRate("btc", "usd")
if err != nil {
log.Fatal(err)
}
fmt.Println(exchange)
// 117.13892user, err := c.CreateUser("[email protected]", "password")
if err != nil {
log.Fatal(err)
}
fmt.Println(user.Email)
// '[email protected]'
fmt.Println(user.ReceiveAddress)
// 'mpJKwdmJKYjiyfNo26eRp4j6qGwuUUnw9x'A receive address is returned also in case you need to send the new user a payment right away.
This will return a list of contacts the user has previously sent to or received from. Useful for auto completion. By default, 30 contacts are returned at a time; use the $page and $limit parameters to adjust how pagination works.
The allowed ContactsParams are:
type ContactsParams struct {
Page int
Limit int
Query string
}params := &coinbase.ContactsParams{
Page: 1,
Limit: 5,
Query: "user",
}
contacts, err := c.GetContacts(params)
if err != nil {
log.Fatal(err)
}
fmt.Println(strings.Join(contacts.Emails, ","))
// '[email protected], [email protected]'You can see a list of method calls here and how they are implemented. They are all wrappers around the Coinbase JSON API.
If there are any methods listed in the API Reference that don't have an explicit function name in the library, you can also call Get, Post, Put, or Delete with a path, params and holder struct for a quick implementation. Holder should be a pointer to some data structure that correctly reflects the structure of the returned JSON response. The library will attempt to unmarshal the response from the server into holder. For example:
balance := map[string]string{} // Holder struct depends on JSON format returned from API
if err := c.Get("account/balance", nil, &balance); err != nil {
log.Fatal(err)
}
fmt.Println(balance)
// map[amount:36.62800000 currency:BTC]Or feel free to add a new wrapper method and submit a pull request.
For an indepth tutorial on how to implement OAuth Authentication, visit this step-by-step tutorial.
To authenticate with OAuth, first create an OAuth application at https://coinbase.com/oauth/applications.
When a user wishes to connect their Coinbase account, redirect them to a URL created with func (o OAuth) CreateAuthorizeUrl(scope []string) string:
o, err := coinbase.OAuthService(YOUR_CLIENT_ID, YOUR_CLIENT_SECRET, YOUR_REDIRECT_URL)
if err != nil {
log.Fatal(err)
}
scope := []string{"all",}
header("Location: " . o.CreateAuthorizeUrl(scope));After the user has authorized your application, they will be redirected back to the redirect URL specified above. A code parameter will be included - pass this into GetTokens to receive a set of tokens:
query := req.URL.Query()
code := query.Get("code")
tokens, err := o.GetTokens(code, "authorization_code")
if err != nil {
log.Fatal(err)
}Store these tokens safely, and use them to make Coinbase API requests in the future. For example:
c := coinbase.OAuthClient(tokens)
amount, err := c.GetBalance()
if err != nil {
log.Fatal(err)
}A full example implementation is available in the example directory. In order to run this example implementation, you will need to install the following dependency:
go get github.com/go-martini/martiniYou will also need to set your coinbase application client_id and client_secret as environment variables by adding these environment variables to your bash config file (i.e ~/.bashrc, ~/.bash_profile, etc...) and reload them:
export COINBASE_CLIENT_ID="YOUR_CLIENT_ID"export COINBASE_CLIENT_SECRET="YOUR_CLIENT_SECRET"source ~/.bash_profileThe last step we need to take is to generate a cert and key pair in order to run our OAuth server over SSL. To do this, run the following command from within the example directory:
go run $(go env GOROOT)/src/pkg/crypto/tls/generate_cert.go --host="localhost"Once you have done this, run the example:
go run OAuthExample.goIf someone gains access to your API Key they will have complete control of your Coinbase account. This includes the abillity to send all of your bitcoins elsewhere.
For this reason, API access is disabled on all Coinbase accounts by default. If you decide to enable API key access you should take precautions to store your API key securely in your application. How to do this is application specific, but it's something you should research if you have never done this before.
In order to run the tests for this library, you will first need to install the Testify/Assert dependency with the following command:
go get github.com/stretchr/testify/assertThen run all tests by executing the following in your command line:
go test . -v
To run either only the endpoint or mock tests, use the below commands:
Endpoint(Live) :
go test . -v -test.run=TestEndpoint
Mock :
go test . -v -test.run=TestMock
If you would like to use the sandbox testnet instead of the live API endpoint, edit the "sandbox" variable in the config package to "true":
Sandbox = true