YII2项目使用的composer.json存在问题，之前通过composer装的库都被删掉了，大概长这样(composer.json内没有require的key)：
{
"config": {
"secure-http": false
},
"autoload":{
"psr-4":{"Mq\\Rabbitmq\\":"vendor/mq/rabbitmq/src/","ZLog\\":"vendor/log/zlog/src/"}
}
}
导致执行composer require安装新库或者composer update更新时会把vendor文件夹里面所有的库都删掉，解决办法是通过composer info找回之前装的库以及版本：
image.png
把这些信息重新写回composer.json，新的composer.json长这样：
{
"config": {
"secure-http": false
},
"autoload":{
"psr-4":{"Mq\\Rabbitmq\\":"vendor/mq/rabbitmq/src/","ZLog\\":"vendor/log/zlog/src/"}
},
"require": {
"cebe/markdown":"1.1.1",
"ezyang/htmlpurifier":"v4.6.0",
"google/apiclient":"v1.1.8",
"guzzlehttp/guzzle":"6.3.0",
"guzzlehttp/promises":"v1.3.1",
"guzzlehttp/psr7":"1.4.2",
"phpspec/php-diff":"v1.1.0",
"psr/http-message":"1.0.1",
"yiisoft/yii2":"2.0.6",
"yiisoft/yii2-bootstrap":"2.0.6",
"yiisoft/yii2-composer":"2.0.5",
"yiisoft/yii2-debug":"2.0.7",
"yiisoft/yii2-gii":"2.0.5",
"yiisoft/yii2-redis":"2.0.5",
"mongodb/mongodb": "^1.4"
}
}
此时还是报错，执行
composer global require "fxp/composer-asset-plugin:1.*"
问题解决。
