Laravel framework knowledge

Laravel:

• Implementation principle of dependency injection
  In the use of laravel When , You can see that dependency injection is heavily used . For example, in the controller HttpRequest object , Various Model Implementation classes of . The advantage of this implementation is that there is no need to new Some examples , Realize the decoupling of modules .
  Dependency injection uses PHP Reflection API Realization , Implementing dependency injection through the container can selectively load the required services , Reduce the overhead of initializing the framework .

• Common set methods
  all() Method , Output in attribute form , Returns the underlying array represented by the collection ;
  avg() Method returns the average ;
  count() Method returns the total number of collections ;
  countBy() Method returns the number of occurrences of a value or the number of occurrences of a value specified by the callback function ;
  diff() Method returns different parts of a collection array , Combine new sets ;
  duplicates() Return duplicate values ;
  first() Return the first value after establishment ;
  flatten() Convert multidimensional array to one dimension ;
  get() Find value by key name ;
  has() Determine whether the specified key exists in the collection ;
  pop() Move out of the last value in the set ;
  slice() Returns the subsequent set of the specified value ;
  sort() Returns the subsequent set of the specified value ;
  where() Series method , Same as database conditions ;
  each() Iterates over the data items in the collection and passes each data item to a given callback .

• Common auxiliary functions
  array_dot () Auxiliary functions allow you to convert a multidimensional array to a one-dimensional array using dot symbols .
  array_get() The function retrieves a value from a multidimensional array using a dot symbol .
  route() Function to generate a route for the specified route URL.
  dump() The function will dump Given variable , It also supports passing in multiple variables at the same time . This is very useful for debugging .
  optional() Function takes an argument , You can call methods of parameters or access properties . If the object passed is null, The method and property will return null, Instead of causing an error or throwing an exception .
  array_divide Function returns two arrays , A key that contains the original array , The other contains the values of the original array .
  array_except Function to delete the specified key from the array / It's worth it .
  array_first Function returns the first element in the array that passes the specified test .
  array_flatten Function to tile a multidimensional array into a one-dimensional array .
  array_only The function returns only the keys specified in the given array / It's worth it .
  array_plunk Function retrieves all values of a given key from an array .
  array_pull Function returns and removes the key from the array / It's worth it .
  array_random Function returns a random value from an array .
  env()
  request()
  app()
  auth()
  response()

• Common middleware
  There are three types of middleware , They are global middleware 、 Middleware group and routing middleware ：

• Global middleware :

If you want to define the middleware in every HTTP Executed on request , Just add the corresponding middleware classes to app/Http/Kernel.php Array properties for $middleware Then you can .

• Assign the middleware to the specified route ：

If you want to assign middleware to a specific route , First of all, we should app/Http/Kernel.php File is assigned to the middleware key, By default , Of the class $routeMiddleware Property contains Laravel Built in middleware , Add your own middleware , Just append it to the back and assign it a key.

• Middleware group

Sometimes you may want to group related middleware into the same group by specifying a key name , This makes it easier to assign them to routes , This can be done by using HTTP Kernel Provided $middlewareGroups Attribute implementation .Laravel It comes with an out of the box web and api Two middleware groups , Each contains information that can be applied to Web and API General middleware for routing .

1. CORS Middleware can be used to add appropriate headers for responses leaving the site （ Cross domain ）;
2. Log middleware can record all requests to enter the site , Thus, it is convenient for us to build the system log system .
3. Authentication middleware
4. CSRF Protect middleware

• PHP Life cycle
  When we ask for a php When you file ,PHP In order to fulfill this request , It's going to happen 5 Life cycle switching of stages :

1. Module initialization （MINIT）, That is to call php.ini The initialization function of the extension specified in , Such as mysql Expand .
2. Request initialization （RINIT）, That is, to initialize the symbol table of variable name and variable value content required for executing this script , Such as $_SESSION Variable .
3. Execute this PHP Script .
4. Request processing complete (Request Shutdown), Call the... Of each module in order RSHUTDOWN Method , Call... For each variable unset function , Such as
   unset $_SESSION Variable .
5. Close the module (Module Shutdown) , PHP Call... For each extension MSHUTDOWN
   Method , This is the last chance for each module to free memory . This means that there is no next request .

• Laravel Life cycle