Questions tagged [smart-contract]

Anything related to decentralized application (dApp) development, concepts, and possibilities with smart contracts, or technical questions for the development of smart contracts.

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109 views

What can prevent one from changing contract code?

I find one major characteristic of EOSIO is that the smart contract code is interchangeable, so that developers can easily fix any bugs or change its logic. But what if someone changes the code to ...
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0answers
38 views

cannot get latest state of table after modifying table in inline action

As shown with code below, I modify table in an inline action, and then want to get the latest data. But the data I get is not the latest. Why? void mycontract::myfunc() { action ( ...
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1answer
90 views

How to have real-time communication in dapp?

How would a real-time 1v1 game work on the EOS Blockchain? I've noticed that many of the games/gambling dapps on EOS are mostly player vs. blockchain, like EOSBet. Could I have real-time updates to ...
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2answers
170 views

Require authorization with conditions require_auth(name1 OR name2)

Is there any possibility to implement conditional require_auth(<condition>) or what is a good practice to make contract accept invocations from a set of predetermined accounts? Is there any ...
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2answers
64 views

Is there a way to prevent me spending tokens until an action is called?

I am creating a smart contract but came to a halt when writing the code. Is there a way, in a smart contract, to prevent me from spending tokens transferred to me by another user through the smart ...
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2answers
125 views

How to avoid cpu usage limits

Task Compute some fields for all table rows when action called contract::priceupdate(price) Input data: Table with 10000 rows Problem Cpu limit 30ms so i cant update whole table in 1 transaction ...
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1answer
131 views

Passing the action name having return type to EOSIO_DISPATCH in EOSIO smart contract

I have following EOSIO smart contract: #include <eosiolib/eosio.hpp> #include <eosiolib/print.hpp> using namespace eosio; class random : public contract { public: using contract::...
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1answer
120 views

Example of resource staking from contract

I'm looking for any relevant code example or documentation describing how to make contract stake resources for some account. I'm aware of delegatebw function of cleos however, I need the following ...
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1answer
250 views

Deploy Contract from browser using eosjs

so I would like to deploy an EOS contract using eosjs. I encountered several problems (especially with converting the .abi and .wasm files). All the examples either use node (so fs is available) or an ...
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0answers
96 views

Where are deferred transaction errors logged to?

I'm trying to learn about deferred transactions. I'm creating a bogus deferred transaction that invokes a non-existent action "fakeaction": transaction out{}; out.actions.emplace_back(...
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1answer
37 views

Can a contract know the creation date of accounts?

Is the creation date of accounts part of consensus? Can I query it within contracts? If so, how to do it?
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1answer
467 views

How to list all balances of tokens managed by an eosio.token contract?

Let's say I have deployed the standard eosio.token contract to an account called "myeosiotoken," and I have used it to create an "ABC" token. Then, I issue 1,000 ABC to "someaccount1" and 2,000 ABC to ...
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1answer
129 views

How to extend the functionality of eosio.token?

I want to create an EOSIO token with additional functionality. For example, I want users to be able to claim() an additional token per day (since e.g. account creation date). Should I create a new ...
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1answer
188 views

Token transfer missing_auth_exception

{ "code":500,"message":"Internal Service Error", "error":{"code":3090004,"name":"missing_auth_exception", "what":"Missing required authority", "details":[{"message":"missing authority of thomsoimj21","...
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1answer
91 views

How to deploy a contract to api-kylin.eosasia.one testnet

I have written a helloworld contract and got compiled that successfully thomsonim123 is my kylin testnet account with some EOS when I want to deploy the contracct to the testnet I get few errors. ...
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1answer
68 views

Is it possible to overload contract actions?

I had a method: -- t.hpp -- [[eosio::action]] void exchange(); -- t.cpp -- void token::exchange() { ... } EOSIO_DISPATCH(eosio::token, (exchange)) and then decided that if a parameter were ...
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1answer
449 views

Authorisation failure with deferred transaction

I have a contract action that does some cleanup: void token::cleanup() { ... } that I want to run asynchronously from another action like this: schedule("cleanup", 10). my scheduling method looks ...
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0answers
79 views

Exception Details: 3080006 deadline_exception: Transaction took too long

I'm getting this error and have read all there is to read on the net (which isn't much) about it. mostly I see others complaining about this error when they run an action for the first time in my ...
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2answers
262 views

Erasing records with for loops

if I want to erase a table: orderbook b(_self, _self.value); auto m = b.get_index<name("idxprod")>(); for (auto &i : m) { m.erase(i); } I get the error: Error 3160005: The table ...
4
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1answer
268 views

How to sort a table?

I'm following this explanation https://developers.eos.io/eosio-cpp/v1.1.0/docs/multi-index-table-tutorial using v1.5.0 of the CDT. Here's what I've got: struct [[eosio::table]] order_struct { ...
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1answer
37 views

Symbol stringification?

an action in my contract accepts an asset: void token::burn(asset a) which I want to print out: printf("Asset [%s] burnt\n", a.symbol.to_string()); except the symbol class does not offer ...
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2answers
46 views

Is there a way to check the histroy of a contract's table?

Is there a way to check the history after deleting the information in the table? For example, check yesterday's table information.
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2answers
63 views

Asset instantiation woes

if I declare an asset: asset a(10, symbol("TST", 0); and I print it: a.print(); I get pretty much what I'd expect: TST the format's not quite right (10 TST would have been better), but ...
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1answer
97 views

Multiple print statements?

given the lack of debugging facilities in EOS contract development I add print() statements to my code, but I'm finding that only the first one gets printed, so: print("HERE\n"); print("HERE\n"); ...
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1answer
448 views

no member named 'print' in 'std::__1::basic_string<char>'

if I declare a string and attempt to print it like this: std::string s; eosio::print(s); the EOS compiler pukes: In file included from t.cpp:1: In file included from ./t.hpp:4: In file included ...
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2answers
134 views

Passing a string to an action?

I have an action that needs to operate on a string: void token::MyAction(std::string key); so I would expect I can make the call like this: cleos push action MyAccount MyAction '["burn"]' -p ...
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2answers
48 views

Referring to permissioned account within contract code?

I've created a table within a contract where I want to store user information. the .emplace() method's first parameter specifies the "scope" (I guess) for data to be stored and thus the user account ...
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1answer
93 views

delay_sec is not accurate for deferred transaction

I have set some seconds but sometimes it is delayed more than 10 minutes. I know that delay_sec is not the accurate time because of the block production mechanism. The real time is much later than it ...
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2answers
43 views

Error about billed CPU time when set Hello World Smart Contract

My VM Spec (VMWare ESXI) CPU : Xeon CPU E5-2620 v2 @ 2.10GHz Memory : 8GB HDD : 70GB EOS 1.5.3 , EOS.CDT 1.4.1 Compile from Source Code with AutoBuild Scripts. I try to create first smart contract ...
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1answer
169 views

EOSIO: name.value secondary index returns end iterator, even though searched value exists in table

I've got a multi-index table going with two secondary indices: TABLE entry { uint64_t id = 0; eosio::name player; std::vector<uint16_t> allocation; ...
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1answer
90 views

Can a deferred transaction make the initial transaction fail

Imagine a user sending me some eosio.token to my contract and when I receive the notification, I start a new deferred transaction that fails later. Can the deferred transaction make the initial ...
2
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1answer
96 views

Multiple Inheritance within ABI files

I have various classes that use multiple inheritance, i.e.: class A { }; class B { }; class C : public A, public B { }; Single inheritance in an ABI file is possible using the base layer as ...
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2answers
224 views

Best way to read data from contract using eosjs or Cleos

How you read the data from your contracts, just by using actions? Or there is another way? Thanks!
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3answers
83 views

Updating existing token contract code

I have deployed a token on main net and called the create method to issue tokens. However, I would like to update the token code to add an extra feature. I can't find any information on the best ...
2
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1answer
164 views

Fixing a smart contract written in old version of eosio.cdt

I am using Ubuntu 18.04 LTS first of all. So I am trying to look up how to start building an EOS dApp, starting with this example on Github. Here is the link: https://github.com/eosasia/eos-todo I ...
2
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2answers
291 views

A possible alternative sign in/login process instead of firebase auth / amazon cognito using an eos contract?

I had the the idea of a secure alternative login process using an EOS smart contract instead of firebase or Amazon cognito. I would like to know if something like this feasible? My idea is somewhat ...
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1answer
52 views

In Eosbetdice contract, in the transfer action, why it is able to emplace a new row in this table?

In Eosbetdice contract, https://gitlab.com/EOSBetCasino/eosbetdice_public/blob/master/EOSBetDice.cpp#L193 The code of the contract in this line should be "eosio.token". I wonder why it doesn't get "...
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1answer
52 views

Blacklisting specific addresses on token::transfer

I've issued a token using eosio.token standard contract. I want to prevent transfers to a number of specific accounts, for a limited time. Since it is temporary, I think I can simply hardcode the ...
1
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1answer
49 views

hello contract: not printing the name

I just set the hello contract and pushed action hi. But it did not print the name. Here is my test command. $cleos --wallet-url http://172.18.0.1:8899 -u http://172.18.0.1:8888 push action shlee ...
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2answers
310 views

I have got "cannot modify objects in table of another contract" when trying to modify a table in my transfer function

I saw some contract implement a handler which will be triggered when receiving EOS token via eosio.token::transfer. I tried to have the same transfer handler and change some row of my table. But I ...
1
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1answer
357 views

How to write a contract to stake my own token without doing transfer?

In my case, I need to write a contract which has an action can stake my own token (issued by my account with eosio.token, like TADO). If A has 10 TADO already, when he stakes 4 TADO, his balance still ...
2
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1answer
352 views

Using name as secondary index

I want to save name in table, and to search by it. It doesn't seems that it is possible to have secondary index with type name for some reason. I would like also to pass name in function and to have ...
0
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1answer
198 views

eos smart contract constructor

when is smart contract constructor triggered for the first time? I know it is triggered every time action is pushed, but what if i want something to be triggered when smart contract is deployed for ...
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1answer
670 views

What does "require_recipient" function actually do in eos?

What does "require_recipient" function actually do? What's the difference between require_recipient and inline action? If contract A calls contract B using require_recipient, can contract B use ...
3
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1answer
530 views

How do I create a Multi-Index DB secondary index from a String?

I'm developing a Smart Contract for EOSIO. I have a Multi-Index table with a uint64_t primary key. I'd like to add a secondary index to the table. Ideally the data I'd be indexing on would be a std::...
0
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1answer
233 views

Access public variables of a TABLE in an EOS Smart Contract

I'm trying to access data inside a smart contract. The contract is visible here for example. The documentation for the smart contract is accessible here An example of an instance of the contract (...
0
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1answer
111 views

What is the ledger in EOS?

When I create a smart contract, e.g: game. what does the ledger store? (EOS tokens, or heathy points, level of user). If the ledger stores heathy points, level, so how I can push it into block (...
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2answers
110 views

EOSIO Tutorial : publishing contract error

I'm working on EOSIO tutorial and now I'm workingon https://developers.eos.io/eosio-home/docs/data-persistence part. Right now, I'm stuck on deploying contract. jongbok@DESKTOP-96ICBPJ:~/eos/...
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2answers
352 views

How to get balance using smartcontract in the new CDT

Is there a way to access the balance(of EOS or any token for that matter) of a given account using smart contract in the new CDT? Thank you
0
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1answer
201 views

How to include external library to smart contract?

I am trying to add libcryptopp library to my contract but when I try to compile with eosio-cpp I get an error that header files cannot be found. This is my code: #include <eosiolib/eosio.hpp> #...

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