P35-P41 fourth_ context

The context is flask A unique concept ,falsk Medium request Objects are global variables , In different threads, we get different responses , For example, this one below us

Context is divided into request context and application context , The above is the request context request, except request,session It is also a request context

Application context has current_app And g object , We haven't used these two before

Catalog

1  current_app

2  g object

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1  current_app

current_app You can return the current application object , Let's write a code to see

• In order to show clearly, we have created a new project named fourth_context

We have created two application objects , Then add an attribute to each application , Then give them a view , Then in the code we run app1

The other runs in the terminal , Run in terminal app2 Change the environment variable first , The environment variable should be changed like this

Enter after activating the environment flask run

We are now visiting 127.0.0.1:5000/home2 Will show app2

If you visit 127.0.0.1:5001/home1 Will show app1

Use current_app Is the purpose of , When it's inconvenient for me to deal with a app When the object , I can use current_app To deal with

When is it inconvenient , At this time, let's take an example

Now we want to app1 Make a blueprint

Then we have to create a blueprint package , And then in __init__ writes

At this time, I found app1 Not imported in file , So you can write like this

This change is a little troublesome , It's not flexible , Then we have a more flexible way of writing , We can write this way

Let's measure , No problem found

2  g object

g The object is flask A temporary variable in , We can pass some data between multiple functions in one request , Every request resets this variable

Let's take an example

Use g object , We can do that func1() Use in g_view() Properties defined

Let's visit

Discovery can be successfully obtained

Later courses (P38-P39) It is about making a certification with a decorator , I don't think it makes sense , So there's no record

P40 stay python console Use context in mode , I don't think it makes any sense

P41 It refers to the internal principle of context , It roughly means that each thread will have another corresponding variable , Then it briefly introduces a project , There is nothing to write