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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call to implicitly-deleted copy constructor

I'm unable to compile a small test contract and am hoping for guidance. I have a class called Account, in the following 2 files: // --- account.hpp #pragma once #include <string> #include &...
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1answer
263 views

Samples with eosio.cdt v1.3.0? multi_index with secondary indexes and get_index

Has anyone been successful getting a contract which uses secondary indexes to compile against the latest versions of the CDT (1.3.2)? I'm having trouble and don't see any updated samples which use ...
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2answers
80 views

SELECT value from “column” for which row is retrieved

Problem Say I have a table with the following structure. int value | asset tokenType 4 | 0 bitcoin 7 | 0 altcoin. Now I also have this function where I pass in an asset and i want to ...
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114 views

Store enum value in table

I have a simple enum (or enum class, neither one is working ) enum vote_option { upvote = 0, downvote and a table which will store a value of that enum type. struct [[eosio::table]] poll { ...
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2answers
238 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 ...
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how to connect eos smart contact with flutter app

flutter has this package name Eosdart,Im able to get the detail from blockchain with app like account detail,but im unable to push the transaction. I want to push a transaction which carry argument ...
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1answer
99 views

Wondering how to fix eosio.token transfer error in contract

I am developing an EOS dapp game When the user acts on the contract after Scatter authentication, the logic is to deposit the bet amount from the user to the contract account. But I get an eosio....
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2answers
190 views

how do i use current_time_point() to store date in eos table

I have tried This way and its not getting store,infact its giving me error,please sugguest if im making any mistake. error: use of undeclared identifier 'current_time_point'; did you mean '...
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1answer
27 views

Return token to owner after initiating a transfer to my contract

Good Day, I am working on a contract where for example, If I send 2 ETH to a contract, ( 1 ETH = 2 Cryptokitty tokens ) then that contract is supposed to return me 4 Cryptokitty tokens. What I Have ...
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1answer
50 views

How to remove deployed smart contract?

I want to sorta "undeploy" smart contract as it was not deployed ever. If it is possible, I hope it will cleanup account's RAM. And I'm not talking about freezing .
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16 views

How to retrieve tx object within contract

I'm trying to retrieve tx within contract, but I only can find tx_hash using read_transaction. Anybody can help me?
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21 views

How to view Macro extended code?

I use this command is ok: eosio-cpp hello.cpp -o hello.wasm But I want to view Macro extended code by option -E - Only run the preprocessor, I use this command: eosio-cpp hello.cpp -E And get ...
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2answers
231 views

How to make a random uint64 to send to an EOS contract

My friend had made an EOS contract and he has asked me to submit a random uint64, I need to generate this in nodejs. Do I need to use a library like big number https://www.npmjs.com/package/big-...
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3answers
483 views

How do you inherit an eosio contract?

I am trying to inherit the 'eosio.token' contract found in '/eos/contracts/eosio.token/' into my new class 'my.token' My CMakeLists.txt looks like file(GLOB ABI_FILES "*.abi") configure_file("${...
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35 views

Catch errors when calling deposit

When I send EOS in a contract to several recipients, it can happen that this fails, e.g. because a recipient has a contract running like that: Example contract of one recipient: [[eosio::on_notify("...
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2answers
642 views

Using find on multi index table

I have a table defined as the following: struct [[ eosio::table, eosio::contract("voting") ]] identity { uint64_t key; key256 identityHash; time_point_sec createdAt; uint64_t ...
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1answer
63 views

what is get(),find(),end(),raw() keywords in eos smart contract?

how and when to useall these keywords and what they actually means? and what is the difference in these 2 statement given below auto itr = loan_table.get(loan_id); auto itr1 = loan_table.find(...
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2answers
183 views

Transferring EOS within Smart Contract

I'm building a Smart Contract that transfers EOS from my contract account to end user accounts. I can not seem to find up to date and correct syntax for transferring EOS using eosio.token from within ...
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1answer
47 views

COMPILATION ERROR error: static_assert failed "Something went wrong. Please report this issue to the github

Getting an error when the code reaches this particular function. Is there something obvious I am missing here? Kindly Note this is Deferred transaction Please ask if anything else is required from ...
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52 views

How can i Improve my code (Transaction took too long)

I have Enough CPU and NET i have staked 13 EOS for each and still unable to run the code. Please suggest if i can improve anything. IS there any problem of table index Got this from developer.io if ...
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2answers
360 views

Best practice to handle table migrations?

What is the best practice for migrating table when a member of a struct is added? For some structs, I have had no problems adding members, but for others I have. I get this error message: $cleos get ...
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1answer
76 views

COMPILATION ERROR error: non-type template argument is not a constant expression

what is causing this error while im compiling ? struct [[eosio::table]] requestForLoan{ uint64_t req_id; name borr_name; uint64_t borr_id; name uwr_name; uint64_t uwr_id;...
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193 views

Error message assertion failure with message: “read”

I made my own smart contract. and tried to erase my table. But it didn't. I will attach the following error { "code": 500, "message": "Internal Service Error", "error": { "code": 3050003, ...
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1answer
37 views

Is there RPC API endpoint to request how much resources account uses?

Is there any way to track or get information about current user account resources consumption using RPC API? I.e. how many operations can be executed with the current tokens or how much RAM or CPU is ...
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1answer
216 views

Can we store date on eosio table?

Is there any direct datatype in eosio to store date? and if not then how can we store dates in eosio table? void mainloan::paymentConfirm(uint64_t pay_id,uint64_t pay_date,double pay_amunt,name from ...
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1answer
141 views

Deferred transaction on EOS [duplicate]

Is it 100% sure that deferred transaction will run on what delay is defined? Is there any possibility that deferred transaction failed to run on defined day? If it fails what is the alternative? ...
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276 views

How to upgrade a multi_index table in a smart contract

I have initially the following multi_index table: struct [[eosio::table]] plastict { uint64_t id; uint64_t type; uint64_t primary_key() const { return id; } }; typedef eosio::multi_index&...
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88 views

When deploying a contract what is important (overall contract/wasm size or amount of functions etc) to not get transaction took too long

when I try to deploy the system.contract I sometimes get transaction took too long with the new eosio version 1.8.1. Now I would like to know on which part of a contract do I need to pay attention ...
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1answer
67 views

EOSIO's BP Benchmark

Today, I am researching how I can draw a diagram for BPs Benchmark, and luckily I found information about Ahola. But I cannot figure it out, how I can get value from Ahola's smart contract to draw a ...
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1answer
242 views

How to convert a public key string to a eosio::publickey object inside a smart contract?

The smart contract takes a string as an input for the public key. I need to convert it into a public key object within the contract.
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1answer
179 views

how to compile eosio.system contracts?

I cloned the eosio.contracts folder from github and made some changes in some of the contracts. Now I would like to compile them and test them, but when I try to compile them with eosio.cdt I get ...
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2answers
41 views

Zero amount transfer?

I just want to use EOSIO as a DB of some events by sending transactions when other events fire. Is it possible to send ZERO amount transfers? The events are millions a day, and I don't know how to ...
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1answer
130 views

no member named 'check' in namespace 'eosio'

I am trying to build a contract and receiving this error: In file included from /usr/opt/eosio.cdt/1.6.1/bin/../include/eosiolib/contracts/eosio/system.hpp:6:[0K /usr/opt/eosio.cdt/1.6.1/bin/../...
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1answer
45 views

I'd like to swap my eos token using eosio.token with EOS coin

I am a DAPP Developer in Korea. I have publish my own token using eosio.token recently. I love to study eos main network system. Now I am trying to learn how swap my token with EOS. So that I was ...
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0answers
68 views

env.is_feature_activated unresolvable while setting up eosio.system contract

I am following BIOS Boot Sequence. I want to set up my own private EOS network that's why I am setting up the EOSIO network. at step 1.12 I am not able to set the eosio.system contract it will give me ...
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1answer
464 views

How to debug eosio::on_notify(“eosio.token::transfer”) actions?

I'm working on a contract that will run an action when receiving tokens. The following code does not run when the account receives EOS or JUNGLE tokens on the Jungle Testnet. #include "./test.hpp" .....
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1answer
50 views

What are the patterns and anti-patterns when programming for EOS?

When programming smart contracts or writing eosjs code, there are certain pitfalls that you might fall into if you are not careful. What are some of the patterns and anti-patterns to be aware of that ...
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0answers
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How does smart contract development differ between each of the EOS.IO side/sister chains?

Most tutorials that exist for smart contract development are directed at the EOS Mainnet chain. But there are several sister and side chains available, and the number is growing all the time. How does ...
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1answer
381 views

How is the json data in a transaction converted to a datastream internally?

I'm looking at datastream.hpp but it does not show how it creates a map or dictionary object as I would expect. Also, does the 'fields' attribute in the .abi file affect what gets deserialised?
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1answer
155 views

How can I get the balance of my account with smart contracts in cdt 1.6

All previous answers before used some function called get_balance, but there is none listed like that in the api https://eosio.github.io/eosio.cdt/1.6.0/functions.html.
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2answers
683 views

Accessing current transaction ID within a smart contract

Is it possible to access the current transaction ID from within a smart contract?
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1answer
81 views

check (within smart contract) if an account is a proxy

How can I verify within a smart contract that an account is a proxy? I know that there is a function is_account, which verifies that a name is an existing account. Is there a way to check if an ...
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1answer
122 views

How to pass a map into an action

I'm trying to pass a map into action, but there is serialization error: Error: expected object containing data: undefined There is a function signature: void init(uint64_t id, const map<uint8_t, ...
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1answer
71 views

Is it possible to set up a smart contract with multiple .cpp and .hpp files?

If we want to make our smart contract code modular, and keep each class, contract, and table in its own file, is it possible to do this, and if so, how?
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1answer
83 views

How can you make sure you know what the contract does when you send an action?

Say you want to send an action to a smart contract, and you know the WASM of the contract. You somehow obtained the original source code which was in C++, you compiled it to WASM, and you got the same ...
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1answer
88 views

where system_contract::claimrewards function is called

Recently I've done some researches in term of how BP earning reward functions implemented. Eventually, I found out that is system_contract::claimrewards however I can't find where it's called. I ...
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1answer
231 views

How should I get the data of the multi_index database?(about contract)

The return value of the action function can only be void type. I can't get data by return value. Now I have saved multiple objects in the multi_index database. I want to get them at once, what should ...
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1answer
716 views

How to pass a list / array / vector to an action? [duplicate]

I need to pass a list of integers to an action. It would be fine to use vectors or arrays, but I can't find one that works. Using vector in the smart contract compiles fine, but then I get this error ...
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2answers
59 views

Transaction took too long while using std::shuffle

Get the error when I push a action on my contract on the local testnet: But if I remove this code from the action I called, there is no problem: class urng: Does anyone know what caused this?I just ...
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1answer
84 views

Can't use fopen, fclose, and ifstream

Here's a screenshot of the problem. This happened when I use eosiocpp to compile my .cpp file into .wast. Does the compiler not allow file reading?

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