interact with a solidity contract through contract's address

Question

i have contract factory which looks like following

pragma solidity ^0.4.8;
import './RentalContract.sol';


contract contractFactory {
  address[] public contracts;


  function getContractCount() public constant returns(uint contractCount) {
    return contracts.length;
  }

  function newContract(uint _rent, uint _security_deposit, string _house, address _owner, address _tenant)
  public constant returns(address) {
    Rental c = new Rental(_rent, _security_deposit, _house, _owner, _tenant);
    contracts.push(c);
    return c;
  }
}

this contract has a function called newContract which creates an object of another contract called RentalContract and returns the address of the newly created object. Now i want to interact with this newly created instance of Rental contract through this address using web3js. How can I achieve this?

EDIT

here is my rental contract

pragma solidity ^0.4.8;

contract Rental {
    struct PaidRent {
        uint id;
        uint value;
    }
    PaidRent[] public paidrents;

    uint public createdTimestamp;
    uint public rent;
    uint public security_deposit;
    string public house;
    address public owner;
    address public tenant;

    enum State {Created, Started, Terminated}
    State public state;
    function Rental(uint _rent, uint _security_deposit, string _house, address _owner, address _tenant) {
        createdTimestamp = block.timestamp;
        rent = _rent;
        security_deposit = _security_deposit;
        house = _house;
        owner = _owner;
        tenant = _tenant;
    }
    modifier require(bool _condition) {
        if(!_condition) throw;
        _;
    }
    modifier ownerOnly() {
        if(msg.sender != owner) throw;
        _;
    }
    modifier TenantOnly() {
        if(msg.sender != tenant) throw;
        _;
    }
    modifier inState(State _state){
        if(_state != state) throw;
        _;
    }

    function getPaidRents() internal returns (PaidRent[]) {
        return paidrents;
    }

    function getHouse() constant returns (string) {
        return house;
    }
    function getowner() constant returns (address) {
        return owner;
    }
    function getTenant() constant returns (address) {
        return tenant;
    }
    function getRent() constant returns (uint) {
        return rent;
    }
    function getDeposit() constant returns (uint) {
        return security_deposit;
    }
    function getContractCreated() constant returns (uint) {
        return createdTimestamp;
    }
    function getContractAddress() constant returns (address) {
        return this;
    }
    function getState() returns (State) {
        return state;
    }
    function CollectEth() payable  {}

    function payRent() TenantOnly inState(State.Started) require(msg.value == rent) {
        owner.transfer(msg.value);
        paidrents.push(PaidRent({
            id : paidrents.length + 1,
            value : msg.value
        }));
    }


    function terminateContract(address deposit_to) inState(State.Started) require(this.balance == security_deposit) {
        deposit_to.transfer(security_deposit);
        state = State.Terminated;
    }



}

i am able to create a new instance of this rental contract thorugh contractFactory's function called newContract. i can interact with this new rental contract by var c2 = Rental.at('0x0109b453ea7734c2c32c3fc73b80de42d6e81f8e') on truffle console. but i don't know how to do this in my angular's service using web3js. if i try to use it in the same way as truffle console it says cannot find name Rental.

Answer 1

The ABI for the newly created contract is the same as the ABI for RentalContrat. The other thing you will need is the address. You may need to implement a function to read the array of addresses. Once you have that, you can follow any of the web3 tutorials available or just to follow the examples for web3 in readthedocs.

I hope this helps

EDIT: https://dappsforbeginners.wordpress.com/tutorials/interactions-between-contracts/

EDTIT after your EDIT:

You have the Rental contract and therefore you have the ABI. Assuming you have injected web3 you can now do:

var Rental = web3.eth.contract(ABI);
var rentalInstance = Rental.at('0x0109b453ea7734c2c32c3fc73b80de42d6e81f8e')

I am assuming the reason it was not finding Rental was that the ABI was not defined.

I hope this helps you.