Your requirements could not be resolved to an installable set of packages.

问题描述

• 今天使用composer 按yii官方文档安装yii时候抛出如下错误

Your requirements could not be resolved to an installable set of packages.

• 完整信息

vagrant@vagrant:~/www$ composer create-project --prefer-dist yiisoft/yii2-app-basic yii2
Installing yiisoft/yii2-app-basic (dev-master fc049dda1286dd9ab955635aa8d0a8e8ee029a88)
    Failed to download yiisoft/yii2-app-basic from dist: The zip extension and unzip command are both missing, skipping.
Your command-line PHP is using multiple ini files. Run `php --ini` to show them.
    Now trying to download from source
  - Installing yiisoft/yii2-app-basic (dev-master fc049dd): Cloning fc049dda12 from cache
Created project in yii2
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - yiisoft/yii2 2.0.x-dev requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.22 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.21 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.20 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.19 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.18 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.17 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.16.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.16 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.15.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.15 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.14.2 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.14.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - yiisoft/yii2 2.0.14 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system.
    - Installation request for yiisoft/yii2 ~2.0.14 -> satisfiable by yiisoft/yii2[2.0.14, 2.0.14.1, 2.0.14.2, 2.0.15, 2.0.15.1, 2.0.16, 2.0.16.1, 2.0.17, 2.0.18, 2.0.19, 2.0.20, 2.0.21, 2.0.22, 2.0.x-dev].

解决办法

• 进入yii框架目录执行如下命令（二选一）

composer install --ignore-platform-reqs 
#或者 
composer update --ignore-platform-reqs