Merge branch 'feature/tutorial-taco-shop-payouts' into 'dev'
Add a tutorial for taco shop payouts See merge request ligolang/ligo!44
This commit is contained in:
Matej Šima
commit
01fe9669e4
@ -2,6 +2,8 @@
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id: cheat-sheet
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title: Cheat Sheet
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---
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<div class="cheatsheet">
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<!--DOCUSAURUS_CODE_TABS-->
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<!--PascaLIGO-->
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@ -32,6 +34,9 @@ title: Cheat Sheet
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|Variant *(pattern)* matching|<pre><code>const a: action = Increment(5);<br/>case a of<br/>| Increment n -> n + 1<br/>| Decrement n -> n - 1<br/>end</code></pre>|
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|Records|<pre><code>type person is record<br/> age: int ;<br/> name: string ;<br/>end<br/><br/>const john : person = record<br/> age = 18;<br/> name = "John Doe";<br/>end<br/><br/>const name: string = john.name;</code></pre>|
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|Maps|<pre><code>type prices is map(nat, tez);<br/><br/>const prices : prices = map<br/> 10n -> 60mtz;<br/> 50n -> 30mtz;<br/> 100n -> 10mtz;<br/>end<br/><br/>const price: option(tez) = prices[50n];</code></pre>|
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|Contracts & Accounts|<pre><code>const destinationAddress : address = "tz1...";<br/>const contract : contract(unit) = get_contract(destinationAddress);</code></pre>|
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|Transactions|<pre><code>const payment : operation = transaction(unit, amount, receiver);</code></pre>|
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<!--END_DOCUSAURUS_CODE_TABS-->
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</div>
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type taco_supply is record
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current_stock : nat;
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max_price : tez;
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end
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type taco_shop_storage is map(nat, taco_supply);
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const ownerAddress: address = "tz1TGu6TN5GSez2ndXXeDX6LgUDvLzPLqgYV";
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const donationAddress: address = "tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx";
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function buy_taco (const taco_kind_index: nat ; var taco_shop_storage : taco_shop_storage) : (list(operation) * taco_shop_storage) is
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begin
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// Retrieve the taco_kind from the contract's storage
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const taco_kind : taco_supply = get_force(taco_kind_index, taco_shop_storage);
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const current_purchase_price : tez = taco_kind.max_price / taco_kind.current_stock;
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if amount =/= current_purchase_price then
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// we won't sell tacos if the amount isn't correct
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fail("Sorry, the taco you're trying to purchase has a different price");
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else
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// Decrease the stock by 1n, because we've just sold one
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taco_kind.current_stock := abs(taco_kind.current_stock - 1n);
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// Update the storage with the refreshed taco_kind
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taco_shop_storage[taco_kind_index] := taco_kind;
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const receiver: contract(unit) = get_contract(ownerAddress);
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const donationReceiver: contract(unit) = get_contract(donationAddress);
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const donationAmount: tez = amount / 10n;
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const operations : list(operation) = list
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transaction(unit, amount - donationAmount, receiver);
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transaction(unit, donationAmount, donationReceiver);
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end;
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end with (operations, taco_shop_storage)
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@ -0,0 +1,180 @@
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---
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id: tezos-taco-shop-payout
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title: Paying out profits from the Taco Shop
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---
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In the [previous tutorial](tutorials/get-started/tezos-taco-shop-smart-contract.md) we've learned how to setup & interact with the LIGO CLI. Followed by implementation of a simple Taco Shop smart contract for our entepreneur Pedro. In this tutorial we'll make sure Pedro has access to tokens that people have spent at his shop when buying tacos.
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<br/>
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<img src="/img/tutorials/get-started/tezos-taco-shop-payout/get-money.svg" width="50%" />
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<div style="opacity: 0.7; text-align: center; font-size: 10px;">
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<div>Icons made by <a href="https://www.flaticon.com/authors/smashicons" title="Smashicons">Smashicons</a> from <a href="https://www.flaticon.com/" title="Flaticon">www.flaticon.com</a> is licensed by <a href="http://creativecommons.org/licenses/by/3.0/" title="Creative Commons BY 3.0" target="_blank">CC 3.0 BY</a></div>
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</div>
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## Analyzing the current contract
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### **`taco-shop.ligo`**
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```
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type taco_supply is record
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current_stock : nat;
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max_price : tez;
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end
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type taco_shop_storage is map(nat, taco_supply);
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function buy_taco (const taco_kind_index: nat ; var taco_shop_storage : taco_shop_storage) : (list(operation) * taco_shop_storage) is
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begin
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// Retrieve the taco_kind from the contract's storage
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const taco_kind : taco_supply = get_force(taco_kind_index, taco_shop_storage);
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const current_purchase_price : tez = taco_kind.max_price / taco_kind.current_stock;
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if amount =/= current_purchase_price then
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// we won't sell tacos if the amount isn't correct
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fail("Sorry, the taco you're trying to purchase has a different price");
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else
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// Decrease the stock by 1n, because we've just sold one
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taco_kind.current_stock := abs(taco_kind.current_stock - 1n);
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// Update the storage with the refreshed taco_kind
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taco_shop_storage[taco_kind_index] := taco_kind;
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end with ((nil : list(operation)), taco_shop_storage)
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```
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### Purchase price formula
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Pedro's Taco Shop contract currently enables customers to buy tacos, at a computed price based on a simple formula.
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```
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const current_purchase_price : tez = taco_kind.max_price / taco_kind.current_stock;
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```
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### Replacing *spendable* smart contracts
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However, due to the [recent protocol upgrade](http://tezos.gitlab.io/mainnet/protocols/004_Pt24m4xi.html) of the Tezos mainnet, Pedro can't access the tokens stored in his Shop's contract directly. This was previously possible via `spendable` smart contracts, which are no longer available in the new protocol. We will have to implement a solution to access tokens from the contract programatically.
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---
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## Designing a payout scheme
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Pedro is a standalone bussines owner, and in our case, he doesn't have to split profits / earnings of the taco shop with anyone. So for the sake of simplicity, we'll payout all the earned XTZ directly to Pedro right after a succesful taco purchase.
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This means that after all the *purchase conditions* of our contract are met - e.g. correct amount is sent to the contract - we'll not only decrease the supply of the individual purchased *taco kind*, but we'll also transfer this amount in a *subsequent transaction* to Pedro's personal address.
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## Forging a payout transaction
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### Defining the recipient
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In order to send tokens, we will need a receiver address - which in our case will be Pedro's personal account. Additionally we'll wrap the given address as a *`contract(unit)`* - which represents either a contract with no parameters, or an implicit account.
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```
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const ownerAddress : address = "tz1TGu6TN5GSez2ndXXeDX6LgUDvLzPLqgYV";
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const receiver : contract(unit) = get_contract(ownerAddress);
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```
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> Would you like to learn more about addresses, contracts and operations in LIGO? Check out the [LIGO cheat sheet](language-basics/cheat-sheet.md)
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### Adding the transaction to the list of output operations
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Now we can transfer the `amount` received by `buy_taco` to Pedro's `ownerAddress`. We will do so by forging a `transaction(unit, amount, receiver)` within a list of operations returned at the end of our contract.
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```
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const payoutOperation : operation = transaction(unit, amount, receiver) ;
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const operations : list(operation) = list
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payoutOperation
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end;
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```
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---
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## Finalizing the contract
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### **`taco-shop.ligo`**
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```
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type taco_supply is record
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current_stock : nat;
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max_price : tez;
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end
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type taco_shop_storage is map(nat, taco_supply);
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const ownerAddress: address = "tz1TGu6TN5GSez2ndXXeDX6LgUDvLzPLqgYV";
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function buy_taco (const taco_kind_index: nat ; var taco_shop_storage : taco_shop_storage) : (list(operation) * taco_shop_storage) is
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begin
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// Retrieve the taco_kind from the contract's storage
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const taco_kind : taco_supply = get_force(taco_kind_index, taco_shop_storage);
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const current_purchase_price : tez = taco_kind.max_price / taco_kind.current_stock;
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if amount =/= current_purchase_price then
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// we won't sell tacos if the amount isn't correct
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fail("Sorry, the taco you're trying to purchase has a different price");
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else
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// Decrease the stock by 1n, because we've just sold one
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taco_kind.current_stock := abs(taco_kind.current_stock - 1n);
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// Update the storage with the refreshed taco_kind
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taco_shop_storage[taco_kind_index] := taco_kind;
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const receiver : contract(unit) = get_contract(ownerAddress);
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const payoutOperation : operation = transaction(unit, amount, receiver);
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const operations : list(operation) = list
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payoutOperation
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end;
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end with (operations, taco_shop_storage)
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```
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### Dry-run the contract
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To confirm that our contract is valid, we can dry run it. As a result we see a *new operation* in the list of returned operations to be executed subsequently.
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```
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ligo dry-run taco-shop.ligo --syntax pascaligo --amount 1 buy_taco 1n "map
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1n -> record
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current_stock = 50n;
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max_price = 50000000mtz;
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end;
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2n -> record
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current_stock = 20n;
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max_price = 75000000mtz;
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end;
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end"
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```
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<img src="/img/tutorials/get-started/tezos-taco-shop-payout/dry-run-1.png" />
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<div style="opacity: 0.7; text-align: center; font-size: 12px; margin-top:-24px;">
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<b>Operation(...bytes)</b> included in the output
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</div>
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<br/>
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**Done! Our tokens are no longer locked in the contract, and instead they are sent to Pedro's personal account/wallet.**
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---
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## 👼 Bonus: donating part of the profits
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Because Pedro is a member of the (STA) Specialty Taco Association, he has decided to donate **10%** of the earnings to the STA. We'll just add a `donationAddress` to the contract, and compute a 10% donation sum from each taco purchase.
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```
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const ownerAddress: address = "tz1TGu6TN5GSez2ndXXeDX6LgUDvLzPLqgYV";
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const donationAddress: address = "tz1KqTpEZ7Yob7QbPE4Hy4Wo8fHG8LhKxZSx";
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```
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```
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const receiver : contract(unit) = get_contract(ownerAddress);
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const donationReceiver : contract(unit) = get_contract(donationAddress);
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const donationAmount: tez = amount / 10n;
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const operations : list(operation) = list
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// Pedro will get 90% of the amount
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transaction(unit, amount - donationAmount, receiver);
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transaction(unit, donationAmount, donationReceiver);
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end;
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```
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This will result into two operations being subsequently executed on the blockchain:
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- Donation transfer (10%)
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- Pedro's profits (90%)
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@ -16,6 +16,6 @@
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"Road Map": ["contributors/road-map/short-term", "contributors/road-map/long-term"]
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},
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"tutorials": {
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"Get Started": ["tutorials/get-started/tezos-taco-shop-smart-contract"]
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"Get Started": ["tutorials/get-started/tezos-taco-shop-smart-contract", "tutorials/get-started/tezos-taco-shop-payout"]
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}
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}
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@ -228,6 +228,10 @@ body > div.fixedHeaderContainer > div > header > div > nav > ul > li:nth-child(5
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background: transparent;
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}
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.cheatsheet tr > td:first-of-type {
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min-width: 240px;
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}
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@media only screen and (min-device-width: 360px) and (max-device-width: 736px) {
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}
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