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.

102 questions with no upvoted or accepted answers
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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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312 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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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
113 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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127 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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2answers
15 views

how to make sure the tx to be included in block

as subject, any way to make sure the tx to be included in block, what i think of is, if the tx meet the condition, then notify the contract to execute the specified action, otherwise notify an account ...
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31 views

How to access data inside multi-index table when using 2D vector / 2D array?

What is going on? :D I write data, but cannot find it after I write it. The following code successfully emplaces the row into the multi-index table: See specifically the vector<vector <...
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2answers
24 views

How check deferred transaction logs on EOS jungle testnet?

As I working on jungle testnet and perform a 1 deferred transaction with some scheduled automatic time. But I failed to see transaction logs on the jungle testnet. Can any please guide me here with ...
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14 views

Implement Shamir Secret Algorithm in smart contract

I need to implement Shamir's Secret algorithm in EOS smart contract. Looking for some open source libraries which will support EOS. I researched some here https://github.com/topics/shamir from which I ...
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1answer
35 views

How to Define and use Array of Strings in Struct?

My Sample Struct and its method // Department Table struct [[eosio::table]] department_info { uint32_t ID; std::string deptname; std::string deptcode; std::...
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17 views

Generate random numbers in the smart contract

I am writing smart contract and stucked on this line : int p = 0; p = (rand() % 997); This is giving error error: use of undeclared identifier 'rand' I do search and got some reference links but ...
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14 views

Read EOSIO contract state with dfuse

I need to read (not stream) data (a table row) from an EOS contract (JavaScript). How? I could use dfuse, because it's free. In fact, I need to read an article HTML (knowing its title) from Everipedia....
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37 views

How can I change quantity in transfer

Good Day!! I want to change add_balance in transfer How can change quantity value in add_balance? Ex) invalid operands to binary expression ('eosio::asset' and 'int') add_balance( to, quantity - 100 , ...
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1answer
68 views

EOS Blockchain How to free up RAM or optimize Smartcontract

We have developed a small program that uses the EOS blockchain and we are storing some of our data in an EOS smart contract. Together with a UUID we are storing the object status. Our goal is to have ...
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13 views

invalid_ref_block_exception

I am trying to test a smart contract via eoslime tool. Using nodeos, but the node is not localhost(default). So, I installed and trying to deploy the smart contract using: eoslime deploy --network.url=...
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14 views

what is eosio.contract 1.9.x for when 1.8.x is still developed?

i see that contract 1.9.1 is out and 1.8.4 has a rc. What are differences or when to use 1.9.x and when 1.8.x? I read somewhere (few months ago) that eosio 2.0 and contract 1.8.x have difficulties ...
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8 views

How to find current week number inside a smart contract?

Is it any effective way to know inside eosio contract which week number is now? e.g. kind of epoch converter for eosio? Rgds
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30 views

How to generate unique string id from given array of strings in smart contract?

I am writing an EOS smart contract in which need to write the action to generate a unique id from the given array. Array consisting of n number of string elements (UUID). Suppose I pass 10 strings to ...
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35 views

How to set vector type field as a secondary index in smart contract?

I want to set a group vector as a secondary index in the user smart contract. group is the list of groups. Following is the changes I am doing: struct [[eosio::table]] usertable { ...
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14 views

How to give and check relationship between two smart contracts?

I am working on two smart contracts Users and Groups. The relation is one user can have many groups. Can I have such a relation in these smart contracts? After smart contract deployment and data ...
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1answer
23 views

Question cost while using token contract

I am sorry to bother you, I am a little confused about the cost while using a token contract: the contract provider will pay all the utilities if a user using the contract including the CPU, NET and ...
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1answer
31 views

make inline transfer contract and using it on jungle testnet

hello everyone i am faceing a problem on jungle testnet i am trying to make a inline transfer but i got this error after i work with the api_endpoint the code is #include <eosio/eosio.hpp> #...
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18 views

Make a trade contract between two tokens like (EOS) & (SYS)

hello everyone i made a small contract that trade between two tokens using eosio.token but if i wasn't work on local test how can i have access to EOS tokens or SYS in the main net and how can i do ...
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1answer
26 views

Declare custom structs

I am trying to create a custom struct called Student in a contract. Where do I declare or define the struct? I tried to define it in the abi file, but the file was over written when I compile the ...
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1answer
95 views

What is the difference between std::string and eosio::string?

Why should I use eosio::string over std::string? What are the use cases where it would make a difference?
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1answer
48 views

Contract transaction cannot be found after i get result of pushSignedTransaction

I've send a contract trans on mainnet use eosjs@20, and i've tried for 4 times, every time i get a trans result, but all of them seemed been drop, i cannot find them on explorer or on chain, can any ...
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1answer
60 views

Is there way to retrieve auto incremented primary key after submission of transaction?

I'm working on sample dApp application to understand the working of multi_index table in EOS smart contract. I have defined two multi_index table. The primary key of table1 is auto incremented using "...
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1answer
55 views

How to check in my contract the incomming amount?

I would like to check in my contract the incomming amount. I tried these: void mycontract(name from, name to, eosio::asset quantity, std::string memo){ check( quantity.amount > 50, "must ...
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2answers
111 views

Use UUID as primary key in multi_index

How can I use a uuid as the primary. struct [[eosio::table]] blackboxdata { name user; std::string uuid; std::string hash; std::string sqlrequest; uint64_t ...
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1answer
50 views

Is it possible to see the RAM delta of a multi_index table operation, or see who is currently paying for a row in a table

My question is in the context of smart contract development, so I'm looking for solutions that work within smart contracts: 1st: Is is possible to see the RAM delta of either an individual ...
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1answer
108 views

How to parse json string in contract?

My contract want to receive transfer with memo in json format, is there any libraries supporting the json parse?
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1answer
49 views

I would like to make listener contract

I would like to make a contract, wich listens to the incoming transfers. How do I make a listener contract, wich listens to incoming transfers on the account?
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2answers
78 views

How to pay for user resources cost for payable action?

I have a smart contract which has a payable action defined. I want to cover the cost of transfering token to my contract, what's the best way to do this? Thanks.
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42 views

Code abstraction

I need a little guidance. I've been structuring my code like this: #include <eosio/eosio.hpp> class [[eosio::contract("table")]] Square { private: struct [[eosio::table]] square { ...
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1answer
43 views

What should I do to specify an optional action parameter for cleos?

I wrote an action that has an optional parameter, as something like: [[eosio::action]] void foo(..., const std::optional<name>& recipient); Then in the generated .abi, it is represented as:...
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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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51 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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1answer
61 views

multi_index table get const_iterator at a specific position

is there a better way than a loop to get the value/const_iterator at a specific position in multi_index table? current: auto idx = _table.get_index<"name"_n>(); const_iterator b; int count = ...
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187 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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87 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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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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2answers
53 views

Is there a way to issue tokens infinitely?

I want to design a system where token supply can grow infinitely. Is it possible not to fix total supply at the token creation moment?
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2answers
67 views

Ico smart contract update

I would like to update this code, because it is CDT 1.2. I would like to update for CDT 1.5 or CDT 1.6. What do I need to change? #include <eosiolib/eosio.hpp> #include <eosiolib/currency....
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73 views

Time point to string

I am currently trying to get the current time using time_point_sec(now()); Does someone know how to convert that to a std::string?
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1answer
83 views

read datastream of length 29 over by -4

enum house_status: uint64_t { NEW = 10, FULL = 20, ONGOING = 30, OVER = 40 }; struct [[eosio::table, eosio::contract("game")]] house{ uint64_t id; uint64_t owner_player_id; ...
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1answer
67 views

Does EOSIO Have Native Contracts Built-Into Protocol Layer?

On the Bitshares site I read https://bitshares.org/technology/industrial-performance-scalability Based upon the lessons we learn from LMAX, we know that a virtual machine for a blockchain should be ...
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1answer
167 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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73 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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1answer
95 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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1answer
72 views

Is there a way to mark accounts like give an account a property value?

Let's say I'm making a game character and each eos account is a unique character. Is there a way to mark an account with different properties like strength, speed, durability, etc....