Omnipay sagepay 2.0 package could not found

Question

i want to integrate omnipay/Sagepay payment method with myproject..i installed vendor folder successfully..but cannot update Sagepay package..if i update there is show terminal error like this " Problem 1 - The requested package omnipay/sagepay 1.0.0 could not be found.

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your min
imum-stability setting"

also which path i choose to install composer weather c:/bin (or) my project folder as c:/xampp/htdocs/myproject

My Composer file is 
{
    "name": "omnipay/sagepay",
    "type": "library",
    "description": "Sage Pay driver for the Omnipay PHP payment processing library",
    "keywords": [
        "gateway",
        "merchant",
        "omnipay",
        "pay",
        "payment",
        "purchase",
        "sage pay",
        "sagepay"
    ],
    "homepage": "https://github.com/omnipay/sagepay",
    "license": "MIT",
    "authors": [
        {
            "name": "Adrian Macneil",
            "email": "adrian@adrianmacneil.com"
        },
        {
            "name": "Omnipay Contributors",
            "homepage": "https://github.com/omnipay/sagepay/contributors"
        }
    ],
    "autoload": {
        "psr-0": { "Omnipay\\SagePay\\" : "src/" }
    },
    "require": {
        "omnipay/common": "~2.0",
        "omnipay/sagepay": "~2.0"
    },
    "require-dev": {
        "omnipay/tests": "~2.0"
    },
    "extra": {
        "branch-alias": {
            "dev-master": "2.0.x-dev"
        }
    }
}

Answer 1

Your composer.json file is defining a new package called omnipay/sagepay, which is obviously not what you want.

Per the installation instructions, all your composer.json file should contain is this:

{
    "require": {
        "omnipay/sagepay": "~2.0"
    }
}

Then run composer update to download the dependencies.