# Extending formatter

Operation formatters may be easily extended for formatting other operation types and Hive-related structures using WaxFormattable TypeScript decorator.

# How it works

@WaxFormattable() decorator specifies a custom formatter class method as a "formatter method" that matches objects with a given property name, by value or by instance of and transforms them. The property name can be specified in the decorator arguments as a string, as a property option or it defaults to the method name as the property name to match. By this, you can avoid problems like matching "get" or "constructor" properties.

Additionally, the new formatters are designed using reflect-metadata library, so if you have a method in the formatter class that does not have the mentioned decorator, then it will not be taken into account when formatting properties.

Options for the main formatter instance are passed to your custom formatter functions along the source and target objects, so you can also adapt your code to previously defined options.

You should not modify source and target values passed to the formatter functions. The target object will be formatted properly based on the formatter functions return value

Inside the formatter method specific to the given property, there will be passed an object as a first argument with readonly properties:

options - Formatter options
source - Source readonly unchanged input value for parsing raw data
target - Target formatter data that might have been previously changed by other formatters

Upon leaving the function scope, you may return the value other than undefined if you want to change the matched property to the given data.

# Regular Usage

# Matching property name by the function name

Test it yourself: src/typescript/formatters/custom-formatters/by-name.ts

import { createHiveChain, WaxFormattable } from '@hiveio/wax';

const chain = await createHiveChain();

class MyFormatters {
  myFunction(value) {
    return value.toString();
  }

  @WaxFormattable()
  myCustomProp({ source }) {
    return this.myFunction(source.myCustomProp);
  }
}

const formatter = chain.formatter.extend(MyFormatters);

const data = {
  myCustomProp: 12542
};

console.log(formatter.waxify`MyData: ${data}`);

MyData: 12542

# Matching property name and value for operation formatting

Test it yourself: src/typescript/formatters/custom-formatters/by-value.ts

import { createHiveChain, WaxFormattable } from '@hiveio/wax';

const chain = await createHiveChain();

class OperationsFormatter {
  @WaxFormattable({ matchProperty: "type", matchValue: "transfer_operation" })
  public transferOperationFormatter({ source }): string {
    return `${source.value.from} transferred ${chain.waxify`${source.value.amount!}`} to ${source.value.to}`;
  }

  @WaxFormattable({ matchProperty: "type", matchValue: "vote_operation" })
  public voteOperationFormatter({ source }): string {
    return `${source.value.voter} voted on @${source.value.author}/${source.value.permlink}`;
  }
}

const formatter = chain.formatter.extend(OperationsFormatter);

const data = [{
  type: "vote_operation",
  value: {
    voter: "otom",
    author: "c0ff33a",
    permlink: "ewxhnjbj",
    weight: 2200
  }
}, {
  type: "transfer_operation",
  value: {
    from: "oneplus7",
    to: "kryptogames",
    amount: {
      amount: "300000",
      precision: 3,
      nai: "@@000000021"
    },
    memo: "Roll under 50 4d434bd943616"
  }
}];

console.log(formatter.format(data));

[
  'otom voted on @c0ff33a/ewxhnjbj',
  'oneplus7 transferred 300.000 HIVE to kryptogames'
]

# Matching property instance of for hive apps operation formatting

Test it yourself: src/typescript/formatters/custom-formatters/by-instance.ts

import { createHiveChain, WaxFormattable, ResourceCreditsOperation, ResourceCreditsOperationData, IFormatFunctionArguments, operation } from '@hiveio/wax';

const chain = await createHiveChain();

/// Create custom formatter definition, specific to given operation type
class HiveAppsOperationsFormatter {
  @WaxFormattable({ matchInstanceOf: ResourceCreditsOperation })
  public rcOperationFormatter({ target }: IFormatFunctionArguments<operation, { custom_json: ResourceCreditsOperationData }>) {
    return `${target.custom_json.from} delegated ${target.custom_json.rc.amount} to ${target.custom_json.delegatees.join(",")}`;
  }
}

/// Initialize transaction object
const tx = await chain.createTransaction();
/// Prepare the operation just to show formatter at work
tx.pushOperation(
  new ResourceCreditsOperation().removeDelegation("gtg", "initminer").authorize("gtg")
);

/// Extend set of configured formatters to be used
const formatter = chain.formatter.extend(HiveAppsOperationsFormatter);
/// Use it to process whole array of operations in general way - without digging into stored item details
console.log(formatter.format(tx.transaction.operations));

[ 'gtg delegated 0 to initminer' ]