I have created a struct patient as follows, and a mapping of uint->patient.

struct patient {
    uint pId;
    string name;
    string phone;
    address payable owner;
    uint numRecords;
    uint[] cost;
    address[] uploader;
    string[] procedure;
    uint[] hospId;
    string[] doctorName;
    bool[] treated;
    string[] image;


mapping(uint => patient) public patients;

I am have created functions to insert data into the mapping. However, when i try to read the data in reactjs using web3,

for (var i = 1; i <= patientCount; i++) {                                                 
            const patient = await container.methods.patients(i).call()

the patient variable only contains the non array parts of the struct. i.e, only pId, name, phone, owner and numRecords is returned.

The value returned is

 {0: BigNumber, 1: "Name", 2: "1234567890", 3: "0x771D3a7C2d6C59D9030731a48D60D8296303fC06", 4: BigNumber, pId: BigNumber, name: "Name", phone: "1234567890", owner: "0x771D3a7C2d6C59D9030731a48D60D8296303fC06", numRecords: BigNumber}
0: BigNumber {_hex: "0x01", _ethersType: "BigNumber"}
1: "NAme"
2: "1234567890"
3: "0x771D3a7C2d6C59D9030731a48D60D8296303fC06"
4: BigNumber {_hex: "0x01", _ethersType: "BigNumber"}
name: "Name"
numRecords: BigNumber {_hex: "0x01", _ethersType: "BigNumber"}
owner: "0x771D3a7C2d6C59D9030731a48D60D8296303fC06"
pId: BigNumber {_hex: "0x01", _ethersType: "BigNumber"}
phone: "1234567890"
__proto__: Object

1 Answer 1


In order to return the whole struct you need to use the ABIEncoderV2 and define your own getter function

pragma solidity ^0.6.0;
pragma experimental ABIEncoderV2;

contract Foo {

  function getPatient(uint id) public view returns (patient memory) {
    return patients[id];

  • Exactly what i was looking for, Thank you. Out of curiosity, is there any way to do this in a single funciton without using experimental features? Without using seperate funcitons for each parameter atleast.. Commented Jun 3, 2020 at 11:29
  • @FarhadBharucha With current solc 0.6 you have to use experimental pragma and a separate function, perhaps in a future version they will make it the default choice but it is not possible yet.
    – Ismael
    Commented Jun 3, 2020 at 14:03

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