= Working with Currencies and Exchange Rates
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The `currency` FieldType provides support for monetary values to Solr/Lucene with query-time currency conversion and exchange rates. The following features are supported:

* Point queries
* Range queries
* Function range queries
* Sorting
* Currency parsing by either currency code or symbol
* Symmetric & asymmetric exchange rates (asymmetric exchange rates are useful if there are fees associated with exchanging the currency)
* Range faceting (using either `facet.range` or `type:range` in `json.facet`) as long as the `start` and `end` values are specified in the same Currency.

== Configuring Currencies

.CurrencyField has been Deprecated
[WARNING]
====
CurrencyField has been deprecated in favor of CurrencyFieldType; all configuration examples below use CurrencyFieldType.
====

The `currency` field type is defined in `schema.xml`. This is the default configuration of this type.

[source,xml]
----
<fieldType name="currency" class="solr.CurrencyFieldType"
           amountLongSuffix="_l_ns" codeStrSuffix="_s_ns"
           defaultCurrency="USD" currencyConfig="currency.xml" />
----

In this example, we have defined the name and class of the field type, and defined the `defaultCurrency` as "USD", for U.S. Dollars. We have also defined a `currencyConfig` to use a file called "currency.xml". This is a file of exchange rates between our default currency to other currencies. There is an alternate implementation that would allow regular downloading of currency data. See <<Exchange Rates>> below for more.

Many of the example schemas that ship with Solr include a <<dynamic-fields.adoc#dynamic-fields,dynamic field>> that uses this type, such as this example:

[source,xml]
----
    <dynamicField name="*_c"   type="currency" indexed="true"  stored="true"/>
----

This dynamic field would match any field that ends in `_c` and make it a currency typed field.

At indexing time, money fields can be indexed in a native currency. For example, if a product on an e-commerce site is listed in Euros, indexing the price field as "1000,EUR" will index it appropriately. The price should be separated from the currency by a comma, and the price must be encoded with a floating point value (a decimal point).

During query processing, range and point queries are both supported.

=== Sub-field Suffixes

You must specify parameters `amountLongSuffix` and `codeStrSuffix`, corresponding to dynamic fields to be used for the raw amount and the currency dynamic sub-fields, for example:

[source,xml]
----
<fieldType name="currency" class="solr.CurrencyFieldType"
           amountLongSuffix="_l_ns" codeStrSuffix="_s_ns"
           defaultCurrency="USD" currencyConfig="currency.xml" />
----

In the above example, the raw amount field will use the `"*_l_ns"` dynamic field, which must exist in the schema and use a long field type, i.e., one that extends `LongValueFieldType`.  The currency code field will use the `"*_s_ns"` dynamic field, which must exist in the schema and use a string field type, i.e., one that is or extends `StrField`.

.Atomic Updates won't work if dynamic sub-fields are stored
[NOTE]
====
As noted on <<updating-parts-of-documents.adoc#field-storage,Updating Parts of Documents>>, stored dynamic sub-fields will cause indexing to fail when you use Atomic Updates. To avoid this problem, specify `stored="false"` on those dynamic fields.
====

== Exchange Rates

You configure exchange rates by specifying a provider. Natively, two provider types are supported: `FileExchangeRateProvider` or `OpenExchangeRatesOrgProvider`.

=== FileExchangeRateProvider

This provider requires you to provide a file of exchange rates. It is the default, meaning that to use this provider you only need to specify the file path and name as a value for `currencyConfig` in the definition for this type.

There is a sample `currency.xml` file included with Solr, found in the same directory as the `schema.xml` file. Here is a small snippet from this file:

[source,xml]
----
<currencyConfig version="1.0">
  <rates>
    <!-- Updated from http://www.exchangerate.com/ at 2011-09-27 -->
    <rate from="USD" to="ARS" rate="4.333871" comment="ARGENTINA Peso" />
    <rate from="USD" to="AUD" rate="1.025768" comment="AUSTRALIA Dollar" />
    <rate from="USD" to="EUR" rate="0.743676" comment="European Euro" />
    <rate from="USD" to="CAD" rate="1.030815" comment="CANADA Dollar" />

    <!-- Cross-rates for some common currencies -->
    <rate from="EUR" to="GBP" rate="0.869914" />
    <rate from="EUR" to="NOK" rate="7.800095" />
    <rate from="GBP" to="NOK" rate="8.966508" />

    <!-- Asymmetrical rates -->
    <rate from="EUR" to="USD" rate="0.5" />
  </rates>
</currencyConfig>
----

=== OpenExchangeRatesOrgProvider

You can configure Solr to download exchange rates from http://www.OpenExchangeRates.Org[OpenExchangeRates.Org], with updates rates between USD and 170 currencies hourly. These rates are symmetrical only.

In this case, you need to specify the `providerClass` in the definitions for the field type and sign up for an API key. Here is an example:

[source,xml]
----
<fieldType name="currency" class="solr.CurrencyFieldType"
           amountLongSuffix="_l_ns" codeStrSuffix="_s_ns"
           providerClass="solr.OpenExchangeRatesOrgProvider"
           refreshInterval="60"
           ratesFileLocation="http://www.openexchangerates.org/api/latest.json?app_id=yourPersonalAppIdKey"/>
----

The `refreshInterval` is minutes, so the above example will download the newest rates every 60 minutes. The refresh interval may be increased, but not decreased.
