README

API for accessing Polish National Bank (NBP - Narodowy Bank Polski) currency and commodities exchange rates.

Usage

Installing via composer

composer require maciej-sz/nbp-php

Minimal setup

<?php
require_once 'vendor/autoload.php';

use MaciejSz\Nbp\Service\CurrencyAverageRatesService;

$currencyAverages = CurrencyAverageRatesService::new();
$rate = $currencyAverages->fromDay('2023-01-02')->fromTable('A')->getRate('USD');

printf('%s rate is %d', $rate->getCurrencyCode(), $rate->getValue());

USD rate is 4.381100

Examples

All working examples from this README are included in the examples/ directory of the repository.

Services

CurrencyAverageRatesService

This service provides API for accessing average rates published in NBP tables.

`fromMonth` method

Returns flat collection of rates from all NBP tables at given month

$averageRatesFromJanuary = $currencyAverages->fromMonth(2023, 1);

foreach ($averageRatesFromJanuary as $rate) {
    printf(
        '%s rate from %s is %F' . PHP_EOL,
        $rate->getCurrencyCode(),
        $rate->getEffectiveDate()->format('Y-m-d'),
        $rate->getValue()
    );
}

THB rate from 2023-01-02 is 0.126700
USD rate from 2023-01-02 is 4.381100
AUD rate from 2023-01-02 is 2.976700
...

`fromDay` method

Returns a dictionary with NBP tables from given day.

$eurRateFromApril4th = $currencyAverages
    ->fromDay('2023-04-04')
    ->fromTable('A')
    ->getRate('EUR');

echo $eurRateFromApril4th->getValue(); // 4.6785

`fromDayBefore` method

Returns a dictionary with NBP tables from day before given day. This method can be useful in some bookkeeping applications when there is a legislatory need to calculate transfer prices. The legislation requires for the prices to be calculated using currency rate applied in the business day before the actual transfer date. Which is exactly what this method exposes.

Example:

$eurRateFromBeforeJanuary2nd = $currencyAverages
    ->fromDayBefore('2023-01-02')
    ->fromTable('A')
    ->getRate('EUR')
;

printf(
    '%s rate from %s is %F',
    $eurRateFromBeforeJanuary2nd->getCurrencyCode(),
    $eurRateFromBeforeJanuary2nd->getEffectiveDate()->format('Y-m-d'),
    $eurRateFromBeforeJanuary2nd->getValue()
);

EUR rate from 2022-12-30 is 4.689900

`getMonthTablesA` method

Returns the A table iterator from a specific month. Rates here are grouped into tables, which represent the actual data structure provided by NBP. To get the rates there needs to be second iteration:

$aTablesFromMarch = $currencyAverages->getMonthTablesA(2023, 3);

foreach ($aTablesFromMarch as $table) {
    foreach ($table->getRates() as $rate) {
        printf(
            '%s rate from table %s is %F' . PHP_EOL,
            $rate->getCurrencyCode(),
            $table->getNo(),
            $rate->getValue()
        );
    }
}

THB rate from table 042/A/NBP/2023 is 0.126700
USD rate from table 042/A/NBP/2023 is 4.409400
AUD rate from table 042/A/NBP/2023 is 2.981900
...
THB rate from table 043/A/NBP/2023 is 0.126600
USD rate from table 043/A/NBP/2023 is 4.400200
AUD rate from table 043/A/NBP/2023 is 2.963800
...

Example getting specific rate:

$aTablesFromMarch = $currencyAverages->getMonthTablesA(2023, 3);

foreach ($aTablesFromMarch as $table) {
    $chfRate = $table->getRate('CHF');
    printf(
        '%s rate from table %s is %F' . PHP_EOL,
        $chfRate->getCurrencyCode(),
        $table->getNo(),
        $chfRate->getValue()
    );
}

CHF rate from table 042/A/NBP/2023 is 4.703100
CHF rate from table 043/A/NBP/2023 is 4.674300
CHF rate from table 044/A/NBP/2023 is 4.728000
// ...

`getMonthTablesB` method

Returns the B table iterator from a specific month.

$bTablesFromMarch = $currencyAverages->getMonthTablesB(2022, 3);

foreach ($bTablesFromMarch as $table) {
    try {
        $rate = $table->getRate('MNT');
    } catch (CurrencyCodeNotFoundException $e) {
        continue;
    }
    printf(
        '%s rate from table %s is %F' . PHP_EOL,
        $rate->getCurrencyName(),
        $table->getNo(),
        $rate->getValue()
    );
}

tugrik (Mongolia) rate from table 009/B/NBP/2022 is 0.001500
tugrik (Mongolia) rate from table 010/B/NBP/2022 is 0.001529
tugrik (Mongolia) rate from table 011/B/NBP/2022 is 0.001469
tugrik (Mongolia) rate from table 012/B/NBP/2022 is 0.001457
tugrik (Mongolia) rate from table 013/B/NBP/2022 is 0.001417

Warning about missing currencies in table B

In table B there can be multiple currencies with the same code.

It is also possible, that a specific currency is present in table from one day, but is not present in table from the next day.

In such case you should not use the getRate($rate) method but rather iterate over all currencies returned by getRates().

Currency trading rates service

This service is used to get buy and sell currency rates from NBP tables.

`fromMonth` method

Returns trading rates from entire month.

$tradingRatesFromApril = $currencyTrading->fromMonth(2023, 4);

foreach ($tradingRatesFromApril as $rate) {
    printf(
        "%s rate from %s effective day traded on %s ask price is %s, bid price is %s\n",
        $rate->getCurrencyCode(),
        $rate->getEffectiveDate()->format('Y-m-d'),
        $rate->getTradingDate()->format('Y-m-d'),
        $rate->getAsk(),
        $rate->getBid()
    );
}

USD rate from 2023-04-03 effective day traded on 2023-03-31 ask price is 4.3338, bid price is 4.248
AUD rate from 2023-04-03 effective day traded on 2023-03-31 ask price is 2.9072, bid price is 2.8496
CAD rate from 2023-04-03 effective day traded on 2023-03-31 ask price is 3.2033, bid price is 3.1399
EUR rate from 2023-04-03 effective day traded on 2023-03-31 ask price is 4.7208, bid price is 4.6274
...

`fromEffectiveDay` method

Return rates from effective date.

$gbpFromApril4th = $currencyTrading->fromEffectiveDay('2023-04-04')->getRate('GBP');

printf(
    '%s rate from %s effective day traded on %s ask price is %s, bid price is %s',
    $gbpFromApril4th->getCurrencyCode(),
    $gbpFromApril4th->getEffectiveDate()->format('Y-m-d'),
    $gbpFromApril4th->getTradingDate()->format('Y-m-d'),
    $gbpFromApril4th->getAsk(),
    $gbpFromApril4th->getBid()
);

GBP rate from 2023-04-04 effective day traded on 2023-04-03 ask price is 5.3691, bid price is 5.2627

`fromTradingDay` method

Return rates from trading date.

$gbpFromApril4th = $currencyTrading->fromTradingDay('2023-04-04')->getRate('GBP');

printf(
    '%s rate from %s effective day traded on %s ask price is %s, bid price is %s',
    $gbpFromApril4th->getCurrencyCode(),
    $gbpFromApril4th->getEffectiveDate()->format('Y-m-d'),
    $gbpFromApril4th->getTradingDate()->format('Y-m-d'),
    $gbpFromApril4th->getAsk(),
    $gbpFromApril4th->getBid()
);

GBP rate from 2023-04-05 effective day traded on 2023-04-04 ask price is 5.4035, bid price is 5.2965

Gold rates service

This service is used to get gold commodity rates from NBP tables.

`fromMonth` method

Gets all rates from specific month.

$jan2013rates = $goldRates->fromMonth(2013, 1);

foreach ($jan2013rates as $rate) {
    printf(
        'Gold rate from %s is %F' . PHP_EOL,
        $rate->getDate()->format('Y-m-d'),
        $rate->getValue()
    );
}

Gold rate from 2013-01-02 is 165.830000
Gold rate from 2013-01-03 is 166.970000
Gold rate from 2013-01-04 is 167.430000
...

`fromDay` method

Returns a gold rate from specific date.

$goldRateFromJan2nd2014 = $goldRates->fromDay('2014-01-02');

printf(
    'Gold rate from %s is %F',
    $goldRateFromJan2nd2014->getDate()->format('Y-m-d'),
    $goldRateFromJan2nd2014->getValue()
);

Gold rate from 2014-01-02 is 116.350000

`fromDayBefore` method

Returns a gold rate from before a specific date.

$goldRateBeforeJan2nd = $goldRates->fromDayBefore('2014-01-02');

printf(
    'Gold rate from %s is %F',
    $goldRateBeforeJan2nd->getDate()->format('Y-m-d'),
    $goldRateBeforeJan2nd->getValue()
);

Gold rate from 2013-12-31 is 116.890000

Using cache

Note that a library implementing PSR-6 has to be provided in order to use the caching abilities.

The CachedTransport class is a proxy for all other transport implementations. This transport has to be backed by another transport, as it relies on it to make the actual requests that have not been cached yet.

Example

use Symfony\Component\Cache\Adapter\FilesystemAdapter as CachePoolAdapter;

// 1) create repository backed by caching transport
$cachePool = new CachePoolAdapter();
$cachingTransportFactory = CachingTransportFactory::new($cachePool);
$client = NbpWebClient::new(transportFactory: $cachingTransportFactory);
$nbpRepository = NbpWebRepository::new($client);

// 2) create needed services using cache-backed repository:
$goldRates = new GoldRatesService($nbpRepository);

// 3) run multiple times to check the effect of caching:
$start = microtime(true);
$goldRates->fromDayBefore('2013-05-15')->getValue();
$end = microtime(true);
$took = $end - $start;
printf('Getting the rate took %F ms', $took * 1000);

Using custom transport

The library uses Symfony HTTP Client and Guzzle as default transports. If those packages are not available then it falls back to the file_get_contents method. This may not be ideal in some situations. Especially when there is no access to HTTP client packages as may be the case when using PHP version prior to 8.0.

In such cases it is suggested to use different transport. It can be achieved by replacing the TransportFactory of the NbpClient with your own implementation.

$customTransportFactory = new class() implements TransportFactory {
    public function create(string $baseUri): Transport
    {
        return new class() implements Transport {
            public function get(string $path): array
            {
                echo "Requesting resource: {$path}" . PHP_EOL;

                $ch = curl_init();
                $url = NbpWebClient::BASE_URL . $path;
                curl_setopt($ch, CURLOPT_URL, $url);
                curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
                try {
                    $output = curl_exec($ch);
                } finally {
                    curl_close($ch);
                }

                echo 'Request successful' . PHP_EOL;

                return json_decode($output, true);
            }
        };
    }
};

$client = NbpWebClient::new(transportFactory: $customTransportFactory);
$nbpRepository = NbpWebRepository::new($client);
$goldRates = GoldRatesService::new($nbpRepository);

$rate = $goldRates->fromDay('2022-01-03');

printf(
    'Gold rate from %s is %F',
    $rate->getDate()->format('Y-m-d'),
    $rate->getValue()
);

Requesting resource: /api/cenyzlota/2022-01-01/2022-01-31
Request successful
Gold rate from 2022-01-03 is 235.720000

Layers

Service layer

The service consists of facades for the package. Classes here are named services instead of facades due to common understanding of this word as something through which you access the internals of a system.

This layer provides a high level business-oriented methods for interacting with the NBP API. It exposes most common use cases of the nbp-php package and is the likely starting point for all applications using this package. One needs to interact with other layers only for more complex tasks.

The service layer is structured in the way that it directly communicates with the repository layer.

Repository layer

Repository layer allows getting data from NBP API by providing methods that closely reflect the NBP Web API. This layer operates on higher level, hydrated domain objects.

The only constraint here is that the repository layer operates on month-based dates. So for example you can get trading rates from entire month, but in order to retrieve a specific date you have to iterate through the retrieved month (you can use service layer for that). This is by design for the purpose of reducing network traffic to the NBP servers. It also allows simplifying caching on the transport layer, because there is no need for any cache-pooling logic.

Client layer

Client layer is a bridge between the repository and the transport layer. It processes request objects on the input, and then it uses the transport layer to fulfill those requests.

The requests thet client layer uses are higher-level requests then those on the transport layer. They implement NbpClientRequest interface.

Transport layer

The transport layer is responsible for directly interacting with the NBP API. A few independent transport implementations are provided for serving connections to the NBP API.

It is also equipped with a convenient factories which pick the most appropriate implementation depending on installed libraries and configuration.

maciej-sz / nbp-php

Maintainers

Details

README

Usage

Installing via composer

Minimal setup

Examples

Services

CurrencyAverageRatesService

`fromMonth` method

`fromDay` method

`fromDayBefore` method

`getMonthTablesA` method

`getMonthTablesB` method

Warning about missing currencies in table B

Currency trading rates service

`fromMonth` method

`fromEffectiveDay` method

`fromTradingDay` method

Gold rates service

`fromMonth` method

`fromDay` method

`fromDayBefore` method

Using cache

Example

Using custom transport

Layers

Service layer

Repository layer

Client layer

Transport layer

maciej-sz / nbp-php

Maintainers

Details

README

Usage

Installing via composer

Minimal setup

Examples

Services

CurrencyAverageRatesService

fromMonth method

fromDay method

fromDayBefore method

getMonthTablesA method

getMonthTablesB method

Warning about missing currencies in table B

Currency trading rates service

fromMonth method

fromEffectiveDay method

fromTradingDay method

Gold rates service

fromMonth method

fromDay method

fromDayBefore method

Using cache

Example

Using custom transport

Layers

Service layer

Repository layer

Client layer

Transport layer

`fromMonth` method

`fromDay` method

`fromDayBefore` method

`getMonthTablesA` method

`getMonthTablesB` method

`fromMonth` method

`fromEffectiveDay` method

`fromTradingDay` method

`fromMonth` method

`fromDay` method

`fromDayBefore` method