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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65 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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17 views

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
30 views

How to tell a certain contract in indeed used in a dApp?

The dapp review sites often list the contract names a dapp is using. I see that this is added by whoever has added that dApp into the review site. But is there a verifiable way (through an explorer ...
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1answer
125 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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19 views

Hide information in the blockchain

Lets say I want to create a player vs player game with a battlefield and moving armies, the movement and data about the armies and where is it going is put on the blockchain. My question is how to ...
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2answers
128 views

How to get a contract to accept tokens as payment

I keep getting the following error: transaction declares authority '{"actor":"test2","permission":"active"}', but does not have signatures for it under a provided delay of 0 ms, provided permissions [...
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1answer
247 views

Transfer tokens inside a smart contract from an account to another account

I need to write a simple function that would send tokens using a different account action. Exactly the same situation as in these questions: one and two But I have to use not eosio.token contract but ...
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0answers
54 views

Get symbol & contract from asset

I currently have an asset property that stores a value, i.e. 100 EOS which could also be another token like 100 TLOS. Is there a way to extract the symbol and possibly the token contract from that ...
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1answer
455 views

Duplicate symbol WASM compilation error when using header/hpp for contract

I'm looking to use a hpp file as an interface for multiple contracts. I've created a test contract and receiving a WASM compilation error. I based the test contract on the format used by eosio.token....
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0answers
32 views

No tables in abi file

I am trying to write a smart contract but for some reason my tables aren't being added to the abi file and therefore aren't being added to the blockchain. My code is as follows. Am I possibly ...
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1answer
240 views

Broadcast Smart Contract 'Hello World' error

I am going through the eos tutorial but I got stuck at the contract broadcast. When I compile the contract with eosio-cpp -o hello.wasm hello.cpp --abigen the console seems to get stuck and I have ...
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0answers
35 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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2answers
43 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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0answers
33 views

Payment to dapp with text comments best practice

I am new in eos, so maybe i say something strange. I want to create a dapp that can receive payments from mobile wallets with text comments. I imagine this like front end where user type text and ...
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1answer
511 views

How to solve !action_type.empty(): Unknown action hi in contract hello?

I am following this doc: https://developers.eos.io/eosio-home/docs/your-first-contract. This is the hello.cpp contract code which is successfully deployed: #include <eosiolib/eosio.hpp> #...
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91 views

How to solve !action_type.empty(): Unknown action hi in contract hello?

I am following this doc: https://developers.eos.io/eosio-home/docs/your-first-contract. This is the hello.cpp contract code which is successfully deployed: #include <eosiolib/eosio.hpp> #...
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0answers
83 views

How to format string in a contract [closed]

I'm trying to format string using boost library, but EOS gives error <atomic> is not supported on this single threaded system. But, as for me, boost format is the most convenient solution. ...
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0answers
60 views

Signing a users account contract deployment remotely with a users arbitrary signature

What I am trying to do is deploy a contract on the behalf of the user, by getting them to sign the deployment remotely. I have been informed that if I get a arbitrary signature on the setcode, I can ...
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2answers
343 views

What is the difference between transaction.send and action.send?

I found that there are two types of transfer I can use in an EOS contract, but I don't know what is the difference between them. 1st type 2nd type
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0answers
44 views

how to use singleton in eos contract? no member named 'get_or_default' [duplicate]

no member named 'get_or_default' #include <eosiolib/singleton.hpp> struct [[eosio::table]] glo { uint64_t key; uint32_t stamp; EOSLIB_SERIALIZE(glo, (key)(stamp)) }; typedef eosio:...
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36 views

How to make real time my contract transition history

I want to make real time my contract transition history,Do I have to learn what components of EOS blockchain?
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0answers
60 views

How can i prevent another contract call my contract's method?

how can i prevent another contract call my deployed contract? Or how can i know that the caller is an eos account with contract or not. Thanks.
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0answers
38 views

EOS smart contract upgrading/recompiling, variables and symbol mappings

EOS allows to reset the contract code payload, unlike some other blockchains: https://www.reddit.com/r/eos/comments/91aqjx/how_many_contracts_can_an_account_have_on_the_eos/e2ww4la/ How the code ...
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0answers
26 views

How to check if an account has smart contract in my smart contract? [duplicate]

We don't want the account that hold a smart contract to run our smart contract. How can we check this? THanks.
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1answer
124 views

Smart contract error while calling recover_key

Specs I am using the function recover_key from the library crypto.h at the following link: https://github.com/EOSIO/eos/blob/master/contracts/eosiolib/crypto.h Code int compressed_size = ...
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1answer
59 views

other way to let contract account provide for cpu/bandwidth than delegatew/undelegatew?

as far as i can tell it is somehow inconvenient to let the user of an contract "pay" for the cpu time. I thought that the one who manages the contract, has to stake for cpu/bandwidth, so user can use ...
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0answers
13 views

Publish a contract using hardware wallet

Is there a way to publish a contract using hardware wallet (ledger preferably) without ever exposing private keys?
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312 views

How to correctly use Docker to run eosio (including eosiocpp)?

I can get the basic quickstart working very easily but when I try to add smart contract I get a lot of conflicts. I have read an article here claiming - https://medium.com/@ekkis/eos-development-on-...
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258 views

Using recover_key with eosjs

I want to validate user signatures in my smart contract. As I understood, I am supposed to do that with recover_key function from crypto.h I am using JavaScript with eosjs and eosjs-ecc for ...
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1answer
433 views

How to use recover function in crypto.hpp to verify signature and public key

I want to sign some data in client using eosjs-ecc.sign() and result is a string like "SIG_K1_KcTmv..." I want to use the recover_key(const checksum256* digest, const char* sig, size_t siglen, char*...
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2answers
532 views

print in contract not showing output in eosjs docker

i want to print some logs in eosjs docker version. But somehow it is not showing anything. I have set: # print contract's output to console (eosio::chain_plugin) contracts-console = true in the ...
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0answers
158 views

Is there any example of crowdsale contract of EOS? [duplicate]

It should be possible to run crowdsales on EOS blockchain, but I can't find any example or even reference. Is there any example?
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1answer
312 views

Error 3070002: Runtime Error Processing WASM - i64.rem_u by 0

My contract deployed fine. However, when I try to call an action I get the following error: Error 3070002: Runtime Error Processing WASM Error Details: i64.rem_u by 0 And the log from the nodeos: ...
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147 views

How to trigger the user account token stake or unstake automatically by using contract

Actually , I have a scenario that users need to stake his or her own certain tokens on a platform by using eosio contract without worrying the platform will take over the users's tokens. and some ...
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0answers
314 views

How do I add second and third indices to the multi_index object?

I have thoroughly read the documentation and isolated my problem down to a small set of sample code. I'm not sure where my problem is. I am trying to add multiple indices to a multi_index object so ...
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0answers
107 views

Eosflare.io shows the wrong Connector Balance for EOSIO.RAM account?

It currently shows 66730 EOS (http://eosflare.io/account/eosio.ram), but here in the first answer (How to get current (last) RAM price?) is said that it should be 1021789.6640 EOS (see quote.balance). ...
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1answer
114 views

Authorization flow in dapps

How authorization works in EOS dapps? I mean in application layer. For example in a trello like application how we manage to just the participants in the project are able to see the tasks?
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0answers
128 views

unpack_action_data - error: !“unresolvable”: env.free. #

I am trying to use unpack_action_data. void apply(const account_name contract, const account_name act) { if (act == N(transfer)) { transferReceived(eosio::unpack_action_data<...
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1answer
600 views

Ricardian contracts

At what level are Ricardian contracts implemented? Examples I see are in the constitution . Can these be applied at the application level? Eg. A derivation contract with the terms of contract ...
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2answers
44 views

Why the EOS documentation still says Dawn 4.1?

Has the documentation been updated to 1.0?
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1answer
116 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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1answer
298 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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1answer
67 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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2answers
164 views

How to get list of active smart-contracts on EOS

It appears cleos has no way of returning a list of active smart-contracts. Is there another way?
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2answers
41 views

How to call Wax action in PHP

All of the tutorials on building dApps, they use Javascript and then they tell you how NOT to do it by using your PK to create a signature. So I'd like to use PHP on the backend and grab my key from a ...
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3answers
25 views

on_notify does not get triggered

I am using a very simple example: mycontract.hpp: [[eosio::on_notify("eosio.token::transfer")]] void depos(name from, name to, asset quantity, string memo); mycontract.cpp: [[eosio::...
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1answer
48 views

Dispatcher in smart contract

I want to implement dispatcher in a smart contract. I research about this and understand theoretically but I am not getting practically. Exactly why the dispatcher is to be used? The basic thing I got ...
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2answers
68 views

how to define a vector with fixed size?

I want to define a vector of strings with a fixed size 3 in the multi-index table of smart contract. I search and tried different ways which I found for CPP vector like: std::vector<string> abc(...
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1answer
154 views

Multiple smart contracts with single account

I have three smart contracts (A, B, C) and one account (X). As the requirement is I just need only one authority (administrator) who is going to manage all these smart contracts data. So I deployed ...
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1answer
55 views

Trouble using EOSIO built in crypto library (can't resolve headers)

I ran eosio-init on the newest CDT (1.7) and made a -bare project. newtest.cpp #include "newtest.hpp" ACTION newtest::hi( name nm ) { /* fill in action body */ print_f("Name : %\n",nm); } ...