基于php7的项目要安装mongodb类库

公司的一个项目要从php5.6升级到php7版本，项目的mongo类库用不了，看了php手册，发现要对于php7要安装新的类库。php7需要使用的library是 mongodb而不是旧的mongo，所以要在项目中下载这个mongodb（library）。
对于一个要安装mongodb library的项目，直接用composer下载，使用composer require mongodb/mongodb，但是报错
localhost:libraries taiwu$ composer require mongodb/mongodb

Using version ^1.3 for mongodb/mongodb
./composer.json has been updated
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
- mongodb/mongodb 1.3.1 requires ext-mongodb ^1.4.0 -> the requested PHP extension mongodb is missing from your system.
- mongodb/mongodb 1.3.0 requires ext-mongodb ^1.4.0 -> the requested PHP extension mongodb is missing from your system.
- Installation request for mongodb/mongodb ^1.3 -> satisfiable by mongodb/mongodb[1.3.0, 1.3.1].

To enable extensions, verify that they are enabled in your .ini files:
- /usr/local/etc/php/5.6/php.ini
- /usr/local/etc/php/5.6/conf.d/ext-mcrypt.ini
You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

Installation failed, reverting ./composer.json to its original content.上面错误说明两个问题：
a. 我的系统使用php -v，肯定得到的是5.6版本，因为我安装了php7版本，但是没有php7放到PATH中更靠前的设置，所以系统直接使用php时，用了5.6。既然主要用php7就，就要设置下PATH。（用命令export PATH=/usr/local/opt/php70/bin/:$PATH）
b.我的php（这里报错说的是5.6）并没有按照mongodb扩展，这个通过php -v能看出来的。

那么我们先让php7版本成为默认的php指令，修改PATH即可，这样在执行composer，它使用的php就是php7了。这时报错信息，就是php7.0要加上mongodb扩展才行
localhost:libraries taiwu$ echo $PATH
/Library/Frameworks/Python.framework/Versions/3.6/bin:/usr/local/opt/php56/bin:/usr/local/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin  
localhost:libraries taiwu$ export PATH=/usr/local/opt/php70/bin/:$PATH
localhost:libraries taiwu$ echo $PATH
/usr/local/opt/php70/bin/:/Library/Frameworks/Python.framework/Versions/3.6/bin:/usr/local/opt/php56/bin:/usr/local/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/opt/local/bin:/opt/local/sbin:/usr/bin:/bin:/usr/sbin
localhost:libraries taiwu$ composer require mongodb/mongodb
Using version ^1.3 for mongodb/mongodb
./composer.json has been updated
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
    - mongodb/mongodb 1.3.1 requires ext-mongodb ^1.4.0 -> the requested PHP extension mongodb is missing from your system.
    - mongodb/mongodb 1.3.0 requires ext-mongodb ^1.4.0 -> the requested PHP extension mongodb is missing from your system.
    - Installation request for mongodb/mongodb ^1.3 -> satisfiable by mongodb/mongodb[1.3.0, 1.3.1].

  To enable extensions, verify that they are enabled in your .ini files:
    - /usr/local/etc/php/7.0/php.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

Installation failed, reverting ./composer.json to its original content.解决上面的问题，最终让基于php7的项目能安装mongodb library很简单，只要保证系统安装的php7，且安装了mongodb扩展。

下面说一下具体步骤：

1、因为是mac pro，通过homebrew安装软件非常方便,    用它安装php7
使用brew search php7,来查看下载php7的具体参数，如下，homebrew/php/php70就是我要下载的版本
localhost:fanghuwang_global taiwu$ brew search php7
==> Searching local taps...
homebrew/php/php70 ✔ homebrew/php/php70-pspell homebrew/php/php71-imagick homebrew/php/php72-ast
homebrew/php/php70-amqp homebrew/php/php70-pthreads homebrew/php/php71-ioncubeloader homebrew/php/php72-blitz
homebrew/php/php70-apcu homebrew/php/php70-raphf homebrew/php/php71-libsodium@1.0 homebrew/php/php72-couchbase
homebrew/php/php70-apcu-bc homebrew/php/php70-rdkafka homebrew/php/php71-lua homebrew/php/php72-ds
homebrew/php/php70-ast homebrew/php/php70-redis homebrew/php/php71-lz4 homebrew/php/php72-ev
homebrew/php/php70-blitz homebrew/php/php70-ref homebrew/php/php71-lzf homebrew/php/php72-event
homebrew/php/php70-couchbase homebrew/php/php70-scrypt homebrew/php/php71-mailparse homebrew/php/php72-gearman
homebrew/php/php70-ds homebrew/php/php70-snmp homebrew/php/php71-maxminddb homebrew/php/php72-geoip
homebrew/php/php70-ev homebrew/php/php70-sodium homebrew/php/php71-mecab homebrew/php/php72-geos使用brew install homebrew/php/php70，但是报错了，提示冲突的公式（具体含义参考brew官网），按照下面提示操作，使用brew unlink php53即可。
localhost:~ taiwu$ brew install homebrew/php/php70
==> Installing php70 from homebrew/homebrew-php
Error: Cannot install homebrew/php/php70 because conflicting formulae are installed.

php53: because different php versions install the same binaries.

Please `brew unlink php53` before continuing.

Unlinking removes a formula's symlinks from /usr/local. You can
link the formula again after the install finishes. You can --force this
install, but the build may fail or cause obscure side-effects in the
resulting software.
localhost:~ taiwu$ brew unlink php53
Unlinking /usr/local/Cellar/php53/5.3.29_3... 16 symlinks removed继续安装，安装成功。可以看到php的路径等信息如下,

然后执行 export PATH=/usr/local/opt/php70/bin/:$PATH， 这样shell中使用php命令，就是php7.0的了
localhost:~ taiwu$ brew install homebrew/php/php70
==> Installing php70 from homebrew/homebrew-php
==> Downloading https://homebrew.bintray.com/bottles-php/php70-7.0.0-rc.3.yosemite.bottle.2.tar.gz ######################################################################## 100.0%
==> Pouring php70-7.0.0-rc.3.yosemite.bottle.2.tar.gz
==> Caveats
To enable PHP in Apache add the following to httpd.conf and restart Apache:
LoadModule php7_module /usr/local/opt/php70/libexec/apache2/libphp7.so

<FilesMatch .php$>
SetHandler application/x-httpd-php
</FilesMatch>

Finally, check DirectoryIndex includes index.php
DirectoryIndex index.php index.html

The php.ini file can be found in:
/usr/local/etc/php/7.0/php.ini

✩✩✩✩ Extensions ✩✩✩✩

If you are having issues with custom extension compiling, ensure that
you are using the brew version, by placing /usr/local/bin before /usr/sbin in your PATH:

PATH="/usr/local/bin:$PATH"

PHP70 Extensions will always be compiled against this PHP. Please install them
using --without-homebrew-php to enable compiling against system PHP.

✩✩✩✩ PHP CLI ✩✩✩✩

If you wish to swap the PHP you use on the command line, you should add the following to ~/.bashrc,
~/.zshrc, ~/.profile or your shell's equivalent configuration file:

export PATH="$(brew --prefix homebrew/php/php70)/bin:$PATH"

✩✩✩✩ FPM ✩✩✩✩

To launch php-fpm on startup:
mkdir -p ~/Library/LaunchAgents
cp /usr/local/opt/php70/homebrew.mxcl.php70.plist ~/Library/LaunchAgents/
launchctl load -w ~/Library/LaunchAgents/homebrew.mxcl.php70.plist

The control script is located at /usr/local/opt/php70/sbin/php70-fpm

OS X 10.8 and newer come with php-fpm pre-installed, to ensure you are using the brew version you need to make sure /usr/local/sbin is before /usr/sbin in your PATH:

PATH="/usr/local/sbin:$PATH"

You may also need to edit the plist to use the correct "UserName".

Please note that the plist was called 'homebrew-php.josegonzalez.php70.plist' in old versions
of this formula.

To have launchd start homebrew/php/php70 at login:
ln -sfv /usr/local/opt/php70/*.plist ~/Library/LaunchAgents
Then to load homebrew/php/php70 now:
launchctl load ~/Library/LaunchAgents/homebrew.mxcl.php70.plist
==> Summary
2、然后基于这个php7安装mongodb扩展了，
查看php手册，说mac下通过homebrew直接安装即可，http://php.net/manual/zh/mongodb.installation.homebrew.phptaiwudeMacBook-Pro:~ taiwu$ brew install php70-mongodb
==> Installing php70-mongodb from homebrew/php
==> Downloading https://pecl.php.net/get/mongodb-1.4.0.tgz 但是上面页面等了半天没反应，果断手动安装，看手册另一个安装说明，http://php.net/manual/zh/mongodb.installation.manual.php，具体步骤如下：$ git clone https://github.com/mongodb/mongo-php-driver.git $ cd mongo-php-driver
$ git submodule update --init
$ phpize
$ ./configure
$ make all
$ sudo make install要注意的是，因为我是用的新安装的php7来进行安装扩展，所以使用phpize的时候，指明具体路径，用命令/usr/local/opt/php70/bin/phpize 。
最后会提示扩展mongodb.so安装成功。
然后需要在php.ini中进行配置，vi /usr/local/etc/php/7.0/php.ini ，然后加上一句话

extension=mongodb.so

这样通过php -m能查看到mongodb的，这说明php7安装mongodb扩展完成了！！！
3、在基于php7的项目中如果要使用mongodb，需要安装mongodb的library，也即是用户业务层面的代码（这里不是php7的mongodb扩展，而且给用户写代码用的library）
继续查看php手册http://php.net/manual/zh/mongodb.tutorial.library.php，
直接用composer来给一个项目安装mongodb library即可，
$ composer require mongodb/mongodb