What is Get and POST in HTML. Attribute Action and Method

GET Method

The GET method uses the URL string to transmit data. Perhaps you paid attention to long and incomprehensible URLs. For example: function.php? login \u003d alex & email \u003d dezyakin. In this case, the data is processed in Function.php. After the question mark "?" Enumerate the transmitted parameters (the parameter is shared by the "&" sign) with the values: the Login parameter is assigned to the ALEX value, and the email variable value dezyakin. The data will be stored in the superglobal array $ _GET. Let us give an example of using the GET method below:

Login: E-mail: Using a superglobal array $ _Get, we derive the assigned values:* / echo "
login \u003d ". $ _get [" login "]; echo"
email \u003d ". $ _Get [" Email "];?\u003e

Consider this HTML code:

Enter the text:

That data will be sent by the GET method.

If, in the case of a get request, the amount of data that we could transmit is limited to the browser length length, then in the case of the post request, there is no such restriction, and we can transmit significant amounts of information.

Another difference of the POST method from GET, the POST method hides all the variables transmitted to them and their values \u200b\u200bin its body (Entity-Body). In the case of the GET method, they were stored in the query string (Request-URI).

Here is an example of a request made by the POST method:

POST / HTTP / 1.0 \\ R \\ N
HOST: www.site.ru \\ r \\ n
Referer: http://www.site.ru/index.html\\r\\n.
Cookie: Income \u003d 1 \\ R \\ n
Content-Type: Application / X-WWW-FORM-URLENCODED \\ R \\ N
Content-Length: 35 \\ R \\ N
\\ r \\ n
Login \u003d Dima & Password \u003d 12345

Thus, passing data by the POST method, they will be much more difficult to intercept the attacker, because They are hidden from direct viewing, so the method of transmitting data by the POST method is considered to be more secure.

In addition, the POST method can be transmitted not only text, but also multimedia data (pictures, audio, video). There is a special content-type parameter that defines the type of information to be transmitted.

And finally, to get the data that were transmitted by this method, the POST variable is used.

Here is an example of processing in PHP:

echo $ _post ['text'];
?>

In the last note, we decided that the browser (client) sends requests to the HTTP server, and the server sends an HTTP response to the HTTP client. These requests and answers are issued according to certain rules. There is something like syntax, as in which sequence should be written. There must be a strictly defined structure.

Let us consider this structure in more detail, which builds requests and answers in the HTTP protocol.

HTTP request consists of three main parts that go in it in the order that is listed below. There is an empty line between the headers and body of the message (as a separator), it is a string translation symbol.

Empty string (separator)

POST and GET requests, what is the difference between them and what is better and for what purposes?

message Body (Entity Body) - optional parameter

Row request - Indicates the transfer method, the URL address to which the HTTP protocol version needs to be accessed.

Headlines - describe the message body, transmit different parameters and other information and information.

message body - This is the data that is transmitted in the request. The message body is an optional parameter and may not be missing.

When we get a response from the server, the message body is most often the contents of a web page. But, when queries to the server, it can also sometimes be present, for example, when we convey the data that was filled in the feedback form to the server.

In more detail, each query element, we will look at the following notes.

Let's, for example, consider one real request to the server. I highlighted each part of the query by my color: a query line - green, headlines - orange, the body message is blue.

Request from browser:

Host: Webgyry.info.

Cookie: WP-SETTINGS

Connection: Keep-Alive

The following example already has a message body.

Server Answer:

Content-Type: text / html; Charset \u003d UTF-8

Transfer-encoding: chunked

Connection: Keep-Alive

Keep-Alive: Timeout \u003d 5

X-pingback: //webgyry.info/xmlrpc.php

Here are the messages of the client and the HTTP server.

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HTTP client sends a request to the server in the form of a request-request, which has the following format:

• Query Row (Mandatory Element)
• Title (optional element)
• Empty string (mandatory element)
• Message body (optional element)

Consider each of these elements separately.

Row request

The query string begins with a method token, after which the URI query and the protocol version follow. Elements are scattered from each other spaces:

Consider this item in more detail

Request method

This element indicates a method that must be called on the server side to the specified URI inferction.

There are eight methods in HTTP:

• Head.
  Used to get the status string and header from the URI server. Does not change the data.
• Get.
  Used to receive data from the server to the specified URI. Does not change the data.
• POST.
  Used to send data to the server (for example, information about the developer, etc.) using HTML forms.
• Put.
  Replaces all previous data on the resource new downloaded data.
• Delete.
  Removes all current data on a resource defined by URI.
• Connect.
  Sets the tunnel connection to the server according to the specified URI.
• Options.
  Describes the connection properties for the specified resource.
• Trace
  Provides a message containing the return trace of the resource specified in the URI.

URI request

URI (Uniform Resource Identifier) \u200b\u200bis a resource identifier to which the query is sent. Below is the most common URI format:

‘*’ Used when an HTTP request does not apply to a specific resource, but to the server. Used only in the case when the method is not necessary to apply to the resource. For example,

absoluteuri. Used when an HTTP request is performed on a proxy. Proxy is requested to transmit a query from an affordable cache and returns the answer. For example:

Asbutivated_Put | a sourcethe most Chatso is used.

Learning to work with Get and Post Requests

A specific resource of a specific server is requested. For example, the client wants to get a resource from the server through the 80th port. The resource address "www.proselyte.net" and sends the following request:

Request header fields

The header fields allow the client to transfer additional information about the request and about themselves to the server itself. These fields act as query modifiers.

Below is the intersection of the most important header fields that can be used:

• Accept-Charset.
• Accept-Encoding
• Accept-Language.
• Authorization
• Expect
• IF-Match.
• IF-Modified-Since
• IF-None-Match
• IF-Range.
• IF-Unmodified-Since
• Range.
• Referer.
• User-Agent

If we decide to implement your own client and your own web server, then we can create your own header fields.

An example of http request

On this we finish learning HTTP requests.
In the next article, we will look at HTTP answers.

One way to send a request via HTTP to the server is to request the GET method. This method is the most common and requests to the server most often occur with its use.

The easiest way to create a Get query can be used to type the URL in the address bar of the browser.

The browser will send the server for approximately the following information:

Get / http / 1.1
Host: Webgyry.info.
User-Agent: Mozilla / 5.0 (Windows NT 6.1; RV: 18.0) GECKO / 20100101 Firefox / 18.0
Accept: text / html, application / xhtml + xml, application / xml; q \u003d 0.9, * / *; q \u003d 0.8
Accept-Language: RU-EN, RU; Q \u003d 0.8, EN-US; Q \u003d 0.5, EN; Q \u003d 0.3
Accept-Encoding: Gzip, Deflate
Cookie: WP-SETTINGS
Connection: Keep-Alive

The request consists of two parts:

1. Request Line (Request Line)

2. Headers (Message Headers)

Please note that the GET query does not have a message body. But, this does not mean that with it, we cannot transfer any information to the server.

Difference between GET and POST methods

This can be done with the help of special GET parameters.

To add GET parameters to request, you need to put a sign "?" At the end of the URL address And after it to start setting them at the following rule:

parameter_name1 \u003d Value Parameters1 & Parameter Name2 \u003d Value Parameters2 & ...

The separator between the parameters is the "&" sign.

For example, if we want to pass two values, the username and its age, it can be done next line:

http://site.ru/page.php?name\u003ddima&age\u003d27

When this query is executed, the data fall into the so-called query_string environment variable from which they can be obtained on the server using the web programming server.

Here is an example, as can be done on PHP.

Echo "Your name:". $ _Get ["Name"]. "
»;
Echo "Your age:". $ _Get ["Age"]. "
»;
?>

The $ _GET design ["parameter name"] allows you to display the value of the transmitted parameter.

As a result of the execution of this code in the browser will be displayed:

Your name: Dima
Your age: 27

we also perform a request to the GET server.

You could notice that the addresses can be contemplated on most sites:

Http: //syt/index.php? Blog \u003d 2

Here, not even knowing PHP, you can guess that we appeal to the file index.php. But what goes after the question of the question, few people know. Everything is quite simple: ? blog \u003d 2 This is an announcement of the global variable "$ _Get [" Blog "]" with the value "2". Thus, I transmit a variable to the script that is responsible for output from the database. Let's write a small script in which you will only clearly see:

if (isset ($ _ get ["blog"])) (
echo $ _get ["blog"];
}
?>

We use the IF () condition operator () as a condition worth this line:

Isset ($ _ get ["blog"])

isset () Allows you to find out if there is a variable that is listed in brackets, that is, the condition that I described in the code sounds like this: if there is a variable $ _Get ["blog"] then output the contents of this variable on the screen. That's what happened:

I think the global variable is clearly created. $ _Get. with the identifier that we have announced in the address bar ( in this case, with the "Blog" identifier)

Now I want to clarify one moment. Suppose we need to declare two variables, how to do it? The first variable is declared after the question of the question "?" The second variable is declared after such a sign "&" ( To be honest I do not know what kind of sign ), here is an example announcement of three variables:

Http: //syt/index.php? A \u003d 1 & b \u003d 2 & c \u003d 3

Here is the output code:

if (ISset ($ _ get ["a"]) and isset ($ _ get ["b"]) and isset ($ _ get ["C"])) (
Echo $ _GET ["A"]. "
";
Echo $ _get ["b"]. "
";
Echo $ _Get ["C"]. "
";
}
?>

The condition sounds like this:

If there is a global variable $ _GET ["A"] and the global variable $ _Get ["b"] and the global variable $ _Get ["C"] then output them on the screen, Here is the result:

Forms

Before we go to pOST. Requests, you need to disassemble what form are? Why do you need? Because the global variable $ _post ["] is created through forms. What is a form? These are fields to enter any information of the user. Fields are in one line, large fields, there are radio buttons, check boxes. We will analyze everything in order ...

Form is a tag:

Elements of form

Your last name name Patronymic:

Your gender:
M.
J.

What country are you from

Russia
Another country

Favorite color (a):

The black:
Red:
White:
Other:

About myself:

Please note that almost every tag has an attribute value.What is he? It records the data you are going to transfer to another page. I hope it is clear

Now if you run this code in the browser, we will see the following:

Form I used an attribute action. with meaning test.php. This means how I have already said that the data from the form is sent to the Test.php file.

POST request

Now write php code which will allow us to see the information you entered. Where is the data stored? In the case of the GET request, our data was lying in the $ _get global variable]. With a post request, the data will lie in the global variable $ _post ["]. In square brackets, it is necessary to prescribe, as in the case of the GET global variable, an identifier. The question is where this identifier take? That's why NAME attribute is needed at the form elements! It is these names that serve us with the key in the global array of POST. Well, let's start the script description:

if (ISset ($ _ post ["submit"])) (
Echo "FULL NAME:" $ _ POST ["FIO"]. "
";
Echo "Gender:" $ _ POST ["SEX"]. "
";
Echo "Country of residence:" $ _ post ["City"]. "
";

Echo "Favorite color (a):
";
Echo $ _Post ["Color_1"]. "
";
Echo $ _post ["Color_2"]. "
";
Echo $ _Post ["Color_3"]. "
";
Echo $ _Post ["Color_4"]. "
";
Echo "About me:" $ _ post ["About"]. "


";
}
?>

The IF condition written is written: if there is a global variable $ _post ["submit"], then display data on the screen. This global variable is created if we click on the Send button, for which this example requires the NAME attribute in the button. You can quite wonder why the button attribute NAME is not required? Everything is quite simple. Usually the programmer does not track the press of the button, and tracks the sent data. For correct operation, for example, the contact form, you must track down without pressing the button, but the correctness of the input of information, and learn whether this information was introduced at all. In our example, we did not check the sent data, and simply traveled to press the button, to simplify the example ... That's what we did:

Conclusion

Well, for today we have disassembled two methods of data transfer between the scripts, and gallopam familiar with the forms. I really hope that this information you have at least somewhere useful. If you have any questions, or thoughts, write comments. Good luck to you, today I have everything!

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