currency.rs

Overview

The currency.rs file defines the OtherCurrency data structure, which represents a currency amount with optional numeric and string representations. It provides functionality for formatting the currency value into different big integer formats asynchronously. This file leverages the async_graphql framework to expose OtherCurrency as a GraphQL object with complex fields, facilitating its use in GraphQL APIs.

Data Structures and Types

OtherCurrency

OtherCurrency is a GraphQL object that encapsulates a currency amount in two forms:

• currency: An optional floating-point number (Option<f64>) representing the currency value in a numeric format.

• value: An optional string (Option<String>) representing the raw or formatted currency value. This field is hidden from the GraphQL schema (#[graphql(skip)]).

The struct is annotated with:

• SimpleObject: Automatically generates GraphQL object type with fields exposed except those marked to skip.

• Clone and Debug traits: Allow cloning and debugging of instances.

• graphql(complex): Enables defining additional complex fields via the ComplexObject implementation.

Methods

value(&self, format: Option<BigIntFormat>) -> Option<String>

• Type: Asynchronous method (returns a Future).

• Parameters:

  • format: Optional BigIntFormat enum specifying the desired format for the big integer representation.

• Returns: Option<String> asynchronously resolving to a formatted string representation of the currency value.

• Description: This method formats the internal value field using the helper function format_big_int_dec. It takes into account the optional format provided and produces a formatted string that suits various big integer display requirements.

• Usage Example:

  let currency = OtherCurrency {
      currency: Some(1234.56),
      value: Some("1234560000000000000000".to_string()),
  };
  let formatted_value = currency.value(Some(BigIntFormat::Decimal)).await;
  println!("Formatted currency value: {:?}", formatted_value);
  

Implementation Details

• The OtherCurrency struct uses async_graphql macros to integrate with GraphQL, allowing the value method to be exposed as a complex, computed field.

• The formatting logic is delegated to the format_big_int_dec function from the helpers module, ensuring consistent formatting across the system.

• The value field is intentionally skipped in the GraphQL schema to control access via the computed value() method instead, allowing formatting on-demand.

• The currency field provides a straightforward numeric value, but it is optional and may be absent depending on data availability.

Interaction with Other Modules

• formats::BigIntFormat: An enum or type that defines possible formats for big integer representation. This is used by the value method to determine how to format the internal string value.

• helpers::format_big_int_dec: A helper function that performs the actual conversion of the stored big integer string into a human-readable decimal format, potentially applying formatting rules defined by BigIntFormat.

• The file resides in a module that includes other currency and formatting utilities, and it integrates into a larger GraphQL API schema by providing currency-related objects.

Diagram: Class Structure of OtherCurrency

classDiagram
class OtherCurrency {
+currency: Option<f64>
-value: Option<String>
+value(format: Option<BigIntFormat>): Option<String> (async)
}

This diagram illustrates the OtherCurrency struct's fields and its asynchronous method for retrieving formatted currency values. The value field is private to GraphQL and accessed through the value() method.