composer.json

{
    "name": "symfony/framework-standard-edition",
    "description": "The \"Symfony Standard Edition\" distribution",
    "provide": { "ext-mongo": "1.6.12" },
    "require": {
        "php": "^7.0",
        "symfony/symfony": "2.8.10",
        "doctrine/orm": "2.5.12",
        "doctrine/annotations": "1.4.*",
        "doctrine/dbal": "2.5.*",
        "doctrine/doctrine-bundle": "1.6.6",
        "doctrine/migrations": "^1.2",
        "doctrine/doctrine-migrations-bundle": "dev-master#861d3564c03b3867845ffd87d9b19f49dc673c69",
        "doctrine/data-fixtures": "1.1.1",
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        "doctrine/mongodb": "1.6.1",
        "doctrine/mongodb-odm": "^1.0.5",
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        "mongodb/mongodb": "1.1.2",
        "alcaeus/mongo-php-adapter": "^1.0.0",
        "stof/doctrine-extensions-bundle": "v1.1.0",
        "knplabs/knp-paginator-bundle": "2.4.2",
        "knplabs/knp-menu-bundle": "2.1.3",
        "knplabs/knp-snappy-bundle": "1.5.2",
        "knplabs/knp-snappy": "1.0.3",
        "twig/extensions": "~1.0",
        "data-uri/twig-extension": "1.0.1",
        "symfony/assetic-bundle": "~2.3",
        "symfony/swiftmailer-bundle": "2.6.3",
        "symfony/monolog-bundle": "~2.4",
        "sensio/distribution-bundle": "~3.0",
        "sensio/framework-extra-bundle": "~3.0",
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        "friendsofsymfony/user-bundle": "1.3.6",
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        "sonata-project/block-bundle": "3.1.1",
        "sonata-project/cache-bundle": "2.4.0",
        "sonata-project/core-bundle": "3.0.3",
        "sonata-project/easy-extends-bundle": "2.3.0",
        "sonata-project/datagrid-bundle": "2.3.0",
        "sonata-project/user-bundle": "3.0.1",
        "sonata-project/doctrine-orm-admin-bundle": "3.0.4",
        "sonata-project/intl-bundle": "2.4.0",
        "sonata-project/media-bundle": "3.1.0",
        "jms/serializer-bundle": "^1.0",
        "genemu/form-bundle": "dev-master",
        "mremi/contact-bundle": "1.3.0",
        "craue/formflow-bundle": "2.1.8",
        "simple-bus/message-bus": "~2.2",
        "simple-bus/symfony-bridge": "^4.1",
        "simple-bus/doctrine-orm-bridge": "^4.0",
        "ocramius/proxy-manager": "2.0.*",
        "zendframework/zend-code": "~3.0.2, !=3.0.3",
        "happyr/doctrine-specification": "0.7.1",
        "swiftmailer/swiftmailer": "5.4.8",
        "guzzlehttp/guzzle": "6.*",
        "php-amqplib/php-amqplib": "2.6.*",
        "php-amqplib/rabbitmq-bundle": "1.14.2",
        "phobetor/rabbitmq-supervisor-bundle": "~2.0",
        "prooph/event-store": "6.6.1",
        "prooph/service-bus-symfony-bundle": "^0.3.0",
        "prooph/event-store-symfony-bundle": "v0.2.x",
        "prooph/event-sourcing": "^4.0",
        "prooph/event-store-doctrine-adapter": "^3.3",
        "prooph/event-store-bus-bridge": "^2.0",
        "ramsey/uuid": "~3.0",
        "mattketmo/uuid-2x-bridge": "*@dev",
        "react/promise" : "^2.5.1",
        "webmozart/assert": "1.2.0"
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    "require-dev": {
        "sensio/generator-bundle": "~2.3",
        "phpunit/phpunit": "5.4.*"
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    "scripts": {
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            "SymfonyStandard\\Composer::hookRootPackageInstall"
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        "post-install-cmd": [
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            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::buildBootstrap",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::clearCache",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installAssets",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installRequirementsFile",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::removeSymfonyStandardFiles"
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            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::buildBootstrap",
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            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installAssets",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::installRequirementsFile",
            "Sensio\\Bundle\\DistributionBundle\\Composer\\ScriptHandler::removeSymfonyStandardFiles"
        ]
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        "symfony-app-dir": "app",
        "symfony-web-dir": "web",
        "symfony-tests-dir": "tests",
        "incenteev-parameters": {
            "file": "app/config/parameters.yml"
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        }
    },
    "autoload": {
        "psr-0": {
            "": "src/",
            "SymfonyStandard": "app/"
        }
    },
    "autoload-dev": {
        "files": [
            "vendor/symfony/symfony/src/Symfony/Component/VarDumper/Resources/functions/dump.php"
        ],
        "psr-4": { "Tests\\": "tests/" }
    },
    "config": {
        "bin-dir": "bin"
    },
    "license": "MIT",
    "type": "project"
}

Partner.php

<?php

/*
 * @ORM\Entity()
 */
class Partner
{
    /**
     * @var PartnerOfferItem[] $offerItems
     * @ORM\OneToMany(targetEntity="Sps\Bundle\BaseBundle\Entity\PartnerOfferItem", mappedBy="partner", indexBy="price_id", fetch="EAGER", orphanRemoval=true)
     * @see http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/changelog/migration_2_5.html#improve-efficiency-of-one-to-many-eager
     * @ORM\OrderBy({"position" = "ASC"})
     */
    protected $offerItems;
}

PartnerOfferItem.php

<?php

/**
 * @ORM\Entity()
 */
class PartnerOfferItem
{
    /**
     * @var Partner $partner
     *
     * @ORM\ManyToOne(targetEntity="Sps\Bundle\BaseBundle\Entity\Partner", inversedBy="offerItems")
     */
    protected $partner;
}

According to @doctrine 2.5 the indexBy should work for OneToMany with EAGER:

• http://docs.doctrine-project.org/projects/doctrine-orm/en/latest/changelog/migration_2_5.html#improve-efficiency-of-one-to-many-eager

Unfortunately it only works when removing fetch="eager".

Discussion on @twitter:

• https://twitter.com/webdevilopers/status/958044185218740225