Go client library (unofficial) for NBP (National Bank of Poland) API: http://api.nbp.pl/en.html.
The module's functions allow you to download currency rates and prices of gold from the NBP API service. Three types have been prepared, corresponding to the basic information provided by the NBP. The NBPTable type is used to download full currency exchange rate tables. Three types of tables A, B, and C are supported, tables A and B contain average currency prices, table C contains 'buy' and 'sell' prices. The TableRaw, TableByDate, TableLast methods allow to download the exchange rate table (or multiple tables) and save the result in internal structures of the NBPTable type. The GetTableCurrent, GetTableToday, etc. methods return the downloaded data in the form of slices of structs. Create[]...] methods return strings prepared for printing or saving to file, based on data downloaded by Table[...] methods. Other types work the same way: NBPCurrency - for downloading the rates of a particular currency, and NBPGold for downloading gold prices.
Disclaimer: nbpapi client library is a private project, in no way related to the National Bank of Poland, except for the use of the NBP public API.
The library is used in the kursNBP project: https://github.com/pjaskulski/kursnbp.
Optionally you can store the results of the query in the memory of your computer. If a cache is enabled, the results are stored for 60 minutes by default, each time you call an identical query again API service it will return the results from the cache instead of querying the real NBP API server. Function EnableCache turns on the caching mechanism, DisableCache turns it off (deleting the memory content).
To install and use:
go get https://github.com/pjaskulski/nbpapi
To clone the repo and invoke the tests:
git clone https://github.com/pjaskulski/nbpapi
cd nbpapi
make test
make coverWarning: by default some tests use (great) httpmock library, to use the real NBP API service it is necessary to set the USEMOCK environment variable to '0'
// How to get table A of currency exchange rates published
// on 12 Nov 2020: function TableByDate("2020-11-12") fetch data, then
// one can get data from nbpTable.Exchange structures (or
// nbpTable.ExchangeC structures, depending of the type of
// table of exchange rates)
var tableNo string
client := nbpapi.NewTable("A")
err: = client.TableByDate("2020-11-12")
if err != nil {
log.Fatal(err)
}
for _, item := range client.Exchange {
tableNo = item.No
for _, currencyItem := range item.Rates {
fmt.Println(tableNo, currencyItem.Code, currencyItem.Currency, currencyItem.Mid)
}
}Output:
221/A/NBP/2020 THB bat (Tajlandia) 0.1256
221/A/NBP/2020 USD dolar amerykański 3.7995
221/A/NBP/2020 AUD dolar australijski 2.7636
221/A/NBP/2020 HKD dolar Hongkongu 0.4901
221/A/NBP/2020 CAD dolar kanadyjski 2.9074
221/A/NBP/2020 NZD dolar nowozelandzki 2.6119
221/A/NBP/2020 SGD dolar singapurski 2.8171
221/A/NBP/2020 EUR euro 4.4868
221/A/NBP/2020 HUF forint (Węgry) 0.012648
221/A/NBP/2020 CHF frank szwajcarski 4.1573
[...]
// today's gold price: function GetPriceToday returns GoldPrice struct
gold := nbpapi.NewGold()
price, err := gold.GetPriceToday()
if err != nil {
fmt.Println(err)
} else {
fmt.Println("Publication date: ", price.Data)
fmt.Println("Price of 1g of gold (PLN): ", price.Price)
}Output:
Publication date: 2020-11-27
Price of 1g of gold (PLN): 218.41
More examples in the \ example folder.
- Global functions:
- EnableCache
- DisableCache
- NBPTable type - complete tables of currency exchange rates:
- create new:
client := NewTable("C") - methods that downloading data into NBPTable type structures:
- TableRaw (only raw data: json or xml)
- TableByDate (raw data and and structures filled with data)
- TableLast (as above)
- methods that return structures with tables of currency exchange rates:
- GetTableCurrent
- GetTableCCurrent
- GetTableToday
- GetTableCToday
- GetTableByDay
- GetTableCByDay
- methods that return data (downloaded previously by TableByDate, or TableLast methods) as text, ready to be printed or saved to a file:
- CreatePrettyOutput
- CreateCSVOutput
- CreateRawOutput
- other methods:
- SetTableType
- create new:
- NBPCurrency type - particular currency exchange rates:
- create new:
client := NewCurrency("A") - methods that downloading data into NBPCurrency type structures:
- CurrencyRaw (only raw data: json or xml)
- CurrencyByDate (raw data and and structures filled with data)
- CurrencyLast (as above)
- CurrencyToday (as above)
- methods that return structures with currency rates:
- GetRateCurrent
- GetRateToday
- GetRateByDate
- methods that return data (downloaded previously) as text, ready to be printed or saved to a file:
- CreatePrettyOutput
- CreateCSVOutput
- CreateRawOutput
- other methods:
- SetTableType
- create new:
- NBPGold type - gold prices:
- create new:
client := NewGold() - methods that downloading data into NBPGold type structures:
- GoldRaw (only raw data: json or xml)
- GoldByDate (raw data and and structures filled with data)
- GoldLast (as above)
- methods that return structures with prices of gold:
- GetPriceToday
- GetPriceCurrent
- GetPriceByDate
- methods that return data (downloaded previously) as text, ready to be printed or saved to a file:
- CreatePrettyOutput
- CreateCSVOutput
- CreateRawOutput
- create new:
Detailed documentation:
package nbpapi // import "github.com/pjaskulski/nbpapi"
VARIABLES
var (
ErrInvalidCurrencyCode error = errors.New("Invalid currency code")
ErrInvalidTableType error = errors.New("Invalid table type, allowed values: A, B or C")
)
errors for invalid code, table type
var CacheOn bool = false
CacheOn - is in-memory cache on/off
var CurrencyValuesA = []string{"THB", "USD", "AUD", "HKD", "CAD", "NZD", "SGD", "EUR", "HUF", "CHF",
"GBP", "UAH", "JPY", "CZK", "DKK", "ISK", "NOK", "SEK", "HRK", "RON",
"BGN", "TRY", "ILS", "CLP", "PHP", "MXN", "ZAR", "BRL", "MYR", "RUB",
"IDR", "INR", "KRW", "CNY", "XDR"}
CurrencyValuesA - list of supported currencies for table type A
var CurrencyValuesB = []string{"MGA", "PAB", "ETB", "AFN", "VES", "BOB", "CRC", "SVC", "NIO", "GMD",
"MKD", "DZD", "BHD", "IQD", "JOD", "KWD", "LYD", "RSD", "TND", "MAD",
"AED", "STN", "BSD", "BBD", "BZD", "BND", "FJD", "GYD", "JMD", "LRD",
"NAD", "SRD", "TTD", "XCD", "SBD", "ZWL", "VND", "AMD", "CVE", "AWG",
"BIF", "XOF", "XAF", "XPF", "DJF", "GNF", "KMF", "CDF", "RWF", "EGP",
"GIP", "LBP", "SSP", "SDG", "SYP", "GHS", "HTG", "PYG", "ANG", "PGK",
"LAK", "MWK", "ZMW", "AOA", "MMK", "GEL", "MDL", "ALL", "HNL", "SLL",
"SZL", "LSL", "AZN", "MZN", "NGN", "ERN", "TWD", "TMT", "MRU", "TOP",
"MOP", "ARS", "DOP", "COP", "CUP", "UYU", "BWP", "GTQ", "IRR", "YER",
"QAR", "OMR", "SAR", "KHR", "BYN", "LKR", "MVR", "MUR", "NPR", "PKR",
"SCR", "PEN", "KGS", "TJS", "UZS", "KES", "SOS", "TZS", "UGX", "BDT",
"WST", "KZT", "MNT", "VUV", "BAM"}
CurrencyValuesB - list of supported currencies for table type B
var CurrencyValuesC = []string{"USD", "AUD", "CAD", "EUR", "HUF", "CHF", "GBP", "JPY", "CZK", "DKK", "NOK",
"SEK", "XDR"}
CurrencyValuesC - list of supported currencies for table type C
var Memory *cache.Cache
Memory - cache
var TableValues = []string{"A", "B", "C"}
TableValues - list of table types
FUNCTIONS
func DisableCache()
DisableCache func - turn off im-memory cache
func EnableCache()
EnableCache func - turn on im-memory cache
func IsValidXML(input string) bool
IsValidXML - func from:
https://stackoverflow.com/questions/53476012/how-to-validate-a-xml
TYPES
type ExchangeTable struct {
Table string `json:"table"`
No string `json:"no"`
EffectiveDate string `json:"effectiveDate"`
Rates []rateTable `json:"rates"`
}
ExchangeTable type
type ExchangeTableC struct {
Table string `json:"table"`
No string `json:"no"`
TradingDate string `json:"tradingDate"`
EffectiveDate string `json:"effectiveDate"`
Rates []rateTableC `json:"rates"`
}
ExchangeTableC type
type GoldRate struct {
Data string `json:"data"`
Price float64 `json:"cena"`
}
GoldRate type
type NBPCurrency struct {
Exchange exchangeCurrency
ExchangeC exchangeCurrencyC
Client *http.Client
// Has unexported fields.
}
NBPCurrency type
func NewCurrency(tableType string) *NBPCurrency
NewCurrency - function creates new currency type
func (c *NBPCurrency) CreateCSVOutput(lang string) string
CreateCSVOutput - function returns currency rates, in the form of CSV (data
separated by a comma), depending on the tableType field: for type A and B
tables a column with an average rate is printed, for type C two columns: buy
price and sell price
Parameters:
lang - 'en' or 'pl'
func (c *NBPCurrency) CreatePrettyOutput(lang string) string
CreatePrettyOutput - function returns exchange rates as formatted table
depending on the tableType field: for type A and B tables a column with an
average rate is printed, for type C two columns: buy price and sell price
Parameters:
lang - 'en' or 'pl'
func (c *NBPCurrency) CreateRawOutput() string
CreateRawOutput - function print just result of request (json or xml)
func (c *NBPCurrency) CurrencyByDate(code, date string) error
CurrencyByDate - function downloads and writes data to exchange (exchangeC)
slice, raw data (json) still available in result field
Function returns error or nil
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(rate for today) or 'current' - current table / rate (last published)
code - ISO 4217 currency code, depending on the type of the
table available currencies may vary
func (c *NBPCurrency) CurrencyLast(code string, last int) error
CurrencyLast - function downloads and writes data to exchange (exchangeC)
slice, raw data (json) still available in result field
Function returns error or nil
Parameters:
code - ISO 4217 currency code, depending on the type of the
table available currencies may vary
last - as an alternative to date, the last <n> tables/rates
can be retrieved
func (c *NBPCurrency) CurrencyRaw(code, date string, last int, format string) error
CurrencyRaw - function downloads data in json or xml form
Function returns error or nil
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(rate for today) or 'current' - current table / rate (last published)
last - as an alternative to date, the last <n> tables/rates
can be retrieved
code - ISO 4217 currency code, depending on the type of the
table available currencies may vary
format - 'json' or 'xml'
func (c *NBPCurrency) CurrencyToday(code string) error
CurrencyToday - function downloads and writes data to exchange (exchangeC)
slice, raw data (json) still available in result field
Function returns error or nil
Parameters:
code - ISO 4217 currency code, depending on the type of the
table available currencies may vary
func (c *NBPCurrency) GetRateByDate(code, date string) ([]Rate, error)
GetRateByDate - function downloads today's currency exchange rate and
returns slice of Rate struct (or error)
Parameters:
code - ISO 4217 currency code, depending on the type of the
table available currencies may vary
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(rate for today) or 'current' - current table / rate (last published)
func (c *NBPCurrency) GetRateCurrent(code string) (Rate, error)
GetRateCurrent - function downloads current currency exchange rate and
return Rate struct (or error)
Parameters:
code - ISO 4217 currency code, depending on the type of the
table available currencies may vary
func (c *NBPCurrency) GetRateToday(code string) (Rate, error)
GetRateToday - function downloads today's currency exchange rate and returns
Rate struct (or error)
Parameters:
code - ISO 4217 currency code, depending on the type of the
table available currencies may vary
func (c *NBPCurrency) SetTableType(tableType string) error
SetTableType - the function allows to set the supported type of exchange
rate table
type NBPGold struct {
GoldRates []GoldRate
Client *http.Client
// Has unexported fields.
}
NBPGold type
func NewGold() *NBPGold
NewGold - function creates new gold type
func (g *NBPGold) CreateCSVOutput(lang string) string
CreateCSVOutput - function returns prices of gold in CSV format (comma
separated data)
Parameters:
lang - 'en' or 'pl'
func (g *NBPGold) CreatePrettyOutput(lang string) string
CreatePrettyOutput - function returns a formatted table of gold prices
Parameters:
lang - 'en' or 'pl'
func (g *NBPGold) CreateRawOutput() string
CreateRawOutput - function returns just result of request (json or xml)
func (g *NBPGold) GetPriceByDate(date string) ([]GoldRate, error)
GetPriceByDate - function returns gold prices (as slice of struct), by date
("YYYY-MM-DD") or range of dates ("YYYY-MM-DD:YYYY-MM-DD")
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(price for today) or 'current' - current gold price (last published)
func (g *NBPGold) GetPriceCurrent() (GoldRate, error)
GetPriceCurrent - function downloads and returns current gold price as
GoldRate struct
func (g *NBPGold) GetPriceToday() (GoldRate, error)
GetPriceToday - function downloads and returns today's gold price, as
GoldRate struct
func (g *NBPGold) GoldByDate(date string) error
GoldByDate - function downloads and writes data to goldRates slice, raw data
(json) still available in NBPGold.result field
Function returns error or nil
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(price for today) or 'current' - current gold price (last published)
func (g *NBPGold) GoldLast(last int) error
GoldLast - function downloads and writes data to GoldRates slice, raw data
(json) still available in NBPGold.result field
Function returns error or nil
Parameters:
last - as an alternative to date, the last <n> prices of gold
can be retrieved
func (g *NBPGold) GoldRaw(date string, last int, format string) error
GoldRaw - function downloads data in json or xml form
Function returns error or nil
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(price for today) or 'current' - current gold price (last published)
last - as an alternative to date, the last <n> prices of gold
can be retrieved
format - 'json' or 'xml'
type NBPTable struct {
Exchange []ExchangeTable
ExchangeC []ExchangeTableC
Client *http.Client
// Has unexported fields.
}
NBPTable type
func NewTable(tableType string) *NBPTable
NewTable - function creates new table type
func (t *NBPTable) CreateCSVOutput(lang string) string
CreateCSVOutput - function prints tables of exchange rates in the console,
in the form of CSV (data separated by a comma), depending on the tableType
field: for type A and B tables a column with an average rate is printed, for
type C two columns: buy price and sell price
Parameters:
lang - 'en' or 'pl'
func (t *NBPTable) CreatePrettyOutput(lang string) string
CreatePrettyOutput - function returns tables of exchange rates as formatted
table, depending on the tableType field: for type A and B tables a column
with an average rate is printed, for type C two columns: buy price and sell
price
Parameters:
lang - 'en' or 'pl'
func (t *NBPTable) CreateRawOutput() string
CreateRawOutput - function returns just result of request (json or xml)
func (t *NBPTable) GetTableByDate(date string) ([]ExchangeTable, error)
GetTableByDate - function retrieves a table of exchange rates for a given
day and return slice of struct ExchangeTable (or error). Version for table
A, B (mid - average price)
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(rate for today) or 'current' - current table / rate (last published)
func (t *NBPTable) GetTableCByDate(date string) ([]ExchangeTableC, error)
GetTableCByDate - function retrieves a table of exchange rates for a given
day and return slice of struct ExchangeTable (or error). Version for table C
(ask, bid - buy, sell prices)
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(rate for today) or 'current' - current table / rate (last published)
func (t *NBPTable) GetTableCCurrent() ([]ExchangeTableC, error)
GetTableCCurrent - function downloads current table of currency exchange
rates and return slice of struct ExchangeTableC (or error), version for
table C (bid, ask - buy, sell prices)
func (t *NBPTable) GetTableCToday() ([]ExchangeTableC, error)
GetTableCToday - function downloads today's table of currency exchange rates
and return slice of struct ExchangeTableC (or error), version for table C
(bid, ask - buy, sell prices)
func (t *NBPTable) GetTableCurrent() ([]ExchangeTable, error)
GetTableCurrent - function downloads current table of currency exchange
rates and return slice of struct ExchangeTable (or error), version for table
A, B (mid - average price)
func (t *NBPTable) GetTableToday() ([]ExchangeTable, error)
GetTableToday - function downloads today's table of currency exchange rates
and return slice of struct ExchangeTable (or error), version for table A, B
(mid - average price)
func (t *NBPTable) SetTableType(tableType string) error
SetTableType - the function allows to set the supported type of exchange
rate table
func (t *NBPTable) TableByDate(date string) error
TableByDate - function downloads and writes data to NBPTable.Exchange
(NBPTable.ExchangeC) slice, raw data (json) still available in
NBPTable.result field
Function returns error or nil
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(rate for today) or 'current' - current table / rate (last published)
func (t *NBPTable) TableLast(last int) error
TableLast - function downloads and writes data to NBPTable.Exchange
(NBPTable.ExchangeC) slice, raw data (json) still available in
NBPTable.result field
Function returns error or nil
Parameters:
last - the last <n> tables/rates can be retrieved
func (t *NBPTable) TableRaw(date string, last int, format string) error
TableRaw - function downloads data in json or xml form, the data will be
placed as [] byte in the result field
Function returns error or nil
Parameters:
date - date in the format: 'YYYY-MM-DD' (ISO 8601 standard),
or a range of dates in the format: 'YYYY-MM-DD:YYYY-MM-DD' or 'today'
(rate for today) or 'current' - current table / rate (last published)
last - as an alternative to date, the last <n> tables/rates
can be retrieved
format - 'json' or 'xml'
type Rate struct {
No string
EffectiveDate string
Mid float64
Bid float64
Ask float64
}
Rate type
- more tests