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DEX tutorial: simplify metadata section, use BigNumber

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mDuo13
2022-04-01 15:23:15 -07:00
parent d286614c6a
commit 1173425ed9
1 changed files with 51 additions and 72 deletions
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123
content/_code-samples/trade-in-the-decentralized-exchange/js/trade-in-the-dex.js
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@@ -9,6 +9,20 @@ if (typeof module !== "undefined") {
var BigNumber = require('bignumber.js')
}
/**
* Convert an XRPL amount, which could be a string (XRP in drops) or an object
* (token amount) to a string for display in one of the following formats:
* "123.456 XRP"
* "123.456 TST.rP9jPyP5kyvFRb6ZiRghAGw5u8SGAmU4bd"
*/
def amt_str(amt) {
if (typeof amt == "string") {
return `${xrpl.dropsToXrp(amt)} XRP`
} else {
return `${amt.value} ${amt.currency}.${amt.issuer}`
}
}
// Connect ---------------------------------------------------------------------
async function main() {
const client = new xrpl.Client('wss://s.altnet.rippletest.net:51233')
@@ -28,10 +42,10 @@ async function main() {
value: "25"}
// 250 TST * 10 XRP per TST * 1.15 fx cost
const we_spend = {currency: "XRP", value: xrpl.xrpToDrops(25*10*1.15)}
const we_spend = {currency: "XRP", value: xrpl.xrpToDrops(25*10*1.05)}
// "Quality" is defined as TakerPays ÷ TakerGets. The lower the "quality"
// number, the better the proposed exchange rate is for the taker.
const proposed_quality = Number(we_spend.value / we_want.value)
const proposed_quality = BigNumber(we_spend.value) / BigNumber(we_want.value)
// Look up Offers. -----------------------------------------------------------
// To buy TST, look up Offers where "TakerGets" is TST:
@@ -54,7 +68,7 @@ async function main() {
// compensate.
const offers = orderbook_resp.result.offers
const want_amt = Number(we_want.value)
const want_amt = BigNumber(we_want.value)
let running_total = 0
if (!offers) {
console.log(`No Offers in the matching book.
@@ -63,7 +77,7 @@ async function main() {
for (const o of offers) {
if (o.quality <= proposed_quality) {
console.log(`Matching Offer found, funded with ${o.owner_funds}`)
running_total += Number(o.owner_funds)
running_total += BigNumber(o.owner_funds)
if (running_total >= want_amt) {
console.log("Full Offer will probably fill")
break
@@ -103,7 +117,7 @@ async function main() {
// Since TakerGets/TakerPays are reversed, the quality is the inverse.
// You could also calculate this as 1/proposed_quality.
const offered_quality = Number(we_want.value / we_spend.value)
const offered_quality = BigNumber(we_want.value) / BigNumber(we_spend.value)
const offers2 = orderbook2_resp.result.offers
let running_total2 = 0
@@ -113,7 +127,7 @@ async function main() {
for (const o of offers2) {
if (o.quality <= offered_quality) {
console.log(`Existing offer found, funded with ${o.owner_funds}`)
running_total2 += Number(o.owner_funds)
running_total2 += BigNumber(o.owner_funds)
} else {
console.log(`Remaining orders are below where ours would be placed.`)
break
@@ -155,86 +169,51 @@ async function main() {
}
// Interpret metadata --------------------------------------------------------
// In JavaScript, you can use getBalanceChanges() to help summarize all the
// balance changes caused by a transaction.
const balance_changes = xrpl.getBalanceChanges(result.result.meta)
console.log("Total balance changes:", JSON.stringify(balance_changes, null, 2))
let offers_affected = 0
for (const affnode of result.result.meta.AffectedNodes) {
if (affnode.hasOwnProperty("ModifiedNode")) {
const mn = affnode.ModifiedNode
if (mn.LedgerEntryType == "AccountRoot") {
if (mn.FinalFields.Account == wallet.address) {
// Found our account in the metadata
const final_xrp_bal = mn.FinalFields.Balance
const prev_xrp_bal = mn.PreviousFields.Balance
if (prev_xrp_bal === undefined) {
console.log(`Total XRP balance unchanged. This usually means the
transaction acquired exactly enough XRP to offset the XRP burned
as a transaction cost. Balance = ${xrpl.dropsToXrp(final_xrp_bal)} XRP`)
} else {
const diff_drops = BigNumber(final_xrp_bal) - BigNumber(prev_xrp_bal)
console.log(`Changed XRP balance by ${xrpl.dropsToXrp(diff_drops)}
to a new value of ${xrpl.dropsToXrp(final_xrp_bal)} XRP. (This
includes the net effect of burning XRP as a transaction cost.)`)
}
}
} else if (mn.LedgerEntryType == "RippleState") {
if (mn.FinalFields.HighLimit.issuer == wallet.address ||
mn.FinalFields.LowLimit.issuer == wallet.address) {
// Modified a trust line we already had
const we_are_low = (mn.FinalFields.LowLimit.issuer == wallet.address)
const currency = mn.FinalFields.Balance.currency
let counterparty
if (we_are_low) {
counterparty = mn.FinalFields.HighLimit.issuer
} else {
counterparty = mn.FinalFields.LowLimit.issuer
}
const final_token_bal = mn.FinalFields.Balance.value
const prev_token_bal = mn.PreviousFields.Balance.value
if (prev_token_bal === undefined) {
console.log(`Balance of ${currency}.${counterparty} unchanged.`)
} else {
let final_bal = BigNumber(final_token_bal)
let diff_tokens = final_bal - BigNumber(prev_token_bal)
if (!we_are_low) {
// RippleState objects store the balance from the low account's
// perspective, so if we are the high account, we negate it to get
// the balance from our perspective instead.
final_bal = -final_bal
diff_tokens = -diff_tokens
}
console.log(`Balance of ${currency}.${counterparty} changed by
${diff_tokens} to a final value of ${final_bal}.`)
}
}
if (affnode.ModifiedNode.LedgerEntryType == "Offer") {
offers_affected += 1
}
} else if (affnode.hasOwnProperty("DeletedNode")) {
if (affnode.DeletedNode.LedgerEntryType == "Offer") {
offers_affected += 1
}
} else if (affnode.hasOwnProperty("CreatedNode")) {
const cn = affnode.CreatedNode
if (cn.LedgerEntryType == "Offer") {
console.log(`Created Offer with TakerPays=${cn.NewFields.TakerPays}
and TakerGets=${cn.NewFields.TakerGets}.`)
} else if (cn.LedgerEntryType == "RippleState") {
if (cn.NewFields.HighLimit.issuer == wallet.address ||
cn.NewFields.LowLimit.issuer == wallet.address) {
const we_are_low = (cn.NewFields.LowLimit.issuer == wallet.address)
let balance = cn.NewFields.Balance.value
if (!we_are_low) {
balance = -balance
}
console.log(`Created ${cn.NewFields.Balance.currency} trust line
between ${cn.NewFields.LowLimit.issuer} and
${cn.NewFields.HighLimit.issuer} with starting balance
${balance}.`)
}
if (affnode.CreatedNode.LedgerEntryType == "RippleState") {
console.log("Created a trust line.")
} else if (affnode.CreatedNode.LedgerEntryType == "Offer") {
const offer = affnode.CreatedNode.NewFields
console.log(`Created an Offer owned by ${offer.Account} with
TakerGets=${amt_str(offer.TakerGets)} and
TakerPays=${amt_str(offer.TakerPays)}.`)
}
}
}
console.log(`Modified or removed ${offers_affected} matching Offer(s)`)
// Check balances ------------------------------------------------------------
console.log("Getting address balances...")
console.log("Getting address balances as of validated ledger...")
const balances = await client.request({
command: "account_lines",
account: wallet.address,
ledger_index: "validated"
})
console.log(balances.result)
console.log(JSON.stringify(balances.result, null, 2))
// Check Offers --------------------------------------------------------------
console.log(`Getting outstanding Offers from ${wallet.address} as of current ledger...`)
const acct_offers = await client.request({
command: "account_offers",
account: wallet.address,
ledger_index: "current"
})
console.log(JSON.stringify(acct_offers.result, null, 2))
client.disconnect()
} // End of main()