Validate Fee Token

fee.validateToken

Validates that a token can be used as a Tempo fee token.

Fee tokens must be unpaused USD-denominated TIP-20 tokens.

Usage

import {  } from './viem.config'
 
const  = await ..({
  : '0x20c0000000000000000000000000000000000001',
})
 
.('Fee token:', )
Fee token: {
  address: '0x20c0000000000000000000000000000000000001',
  id: 1n,
  metadata: {
    decimals: 6,
    name: 'USD Token',
    symbol: 'USD',
    currency: 'USD',
    paused: false,
  },
}

import { ,  } from 'viem/tempo'
 
export const  = .({
  : .('0x...'),
})

Recipes

Screen a User-Entered Token Before Saving It

Catch the specific validation errors to give users actionable feedback before persisting a preference with fee.setUserToken.

import { ,  } from 'viem/tempo'
import {  } from './viem.config'
 
try {
  const {  } = await ..({
    : '0x20c0000000000000000000000000000000000001',
  })
  await ..({ :  })
} catch () {
  if ( instanceof )
    .('This token is paused. Choose another stablecoin.')
  else if ( instanceof )
    .('Fee tokens must be USD-denominated.')
  else throw 
}

import { ,  } from 'viem/tempo'
 
export const  = .({
  : .('0x...'),
})

Build a Fee Token Picker

Validate a list of candidate tokens and build picker options from the returned metadata, skipping candidates that cannot pay fees.

import {  } from './viem.config'
 
const  = [
  '0x20c0000000000000000000000000000000000000',
  '0x20c0000000000000000000000000000000000001',
] as 
 
const : { : string; : string }[] = []
for (const  of ) {
  try {
    const { ,  } = await ..({  })
    .({ , : . })
  } catch {
    continue
  }
}

import { ,  } from 'viem/tempo'
 
export const  = .({
  : .('0x...'),
})

Return Value

type ReturnType = {
  /** Fee token contract address. */
  address: Address
  /** Fee token id. */
  id: bigint
  /** Fee token metadata. */
  metadata: {
    decimals: number
    name: string
    symbol: string
    currency: string
    paused: boolean
  }
}

The fee token address, id, and metadata.

Parameters

token

Type: Address | bigint

Token to validate: a TIP-20 token id or a contract address.

blockNumber (optional)

Type: bigint

Block number to read the state from.

blockOverrides (optional)

Type: BlockOverrides

Block overrides to apply to the state.

blockTag (optional)

Type: BlockTag

Block tag to read the state from.

stateOverride (optional)

Type: StateOverride

State override to apply.

Errors

Error	Description
`InvalidFeeTokenError`	Thrown when the fee token cannot be resolved or read as a valid fee token.
`FeeTokenNotTip20Error`	Thrown when the fee token is not a TIP-20 token.
`FeeTokenNotUsdError`	Thrown when the fee token is not denominated in USD.
`FeeTokenPausedError`	Thrown when the fee token is paused.

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