¿Por qué usar admin-ajax.php y cómo funciona?

1) ¿Por qué usar admin-ajax.phpen lugar de codificar sujsonen un archivo como themes/example/json.php y codificar sus datos allí?

El uso de admin-ajax.php significa queelnúcleo de WordPressestá cargado y disponible. Sineso,necesitaría cargarmanualmente los archivos quenecesita,lo cuales unproceso complicado ypropenso afallar sino conoceel Coremuy,muybien. ¿Y quétanbuenoeres con la seguridad de Javascript?

2) ¿Cómofunciona admin-ajax.php? Noentiendomucho deeso archivo. ¿Cargatodas lasfuncionespara queesté listopara usarlas?

1. Cargaelnúcleo de WordPress,lo que significa quepuede usar cosas como $wpdb y $WP_Query. Esoes hasta la línea 25.
2. Envía algunosencabezados: líneas 37 a 41.
   
   1. Unencabezado detipo de contenido
   2. Unencabezadoparaindicar a losnavegadores queno almacenen los resultadosen caché
   3. Losencabezadosinteresantes son losenviadospor send_nosniff_headers()
   4. y nocache_headers() .
3. Se activaelgancho admin_init.
4. Las accionesprincipales se definen y registran dinámicamente: líneas 46 a 73. Estosno se registrarán amenos que seannecesarios,es decir,amenos que se solicitan através de $_GET o $_POST.
5. Se activaelenlace de API "heartbeat": línea 75
6. Se compruebaelestado "iniciado sesión" del usuario solicitante y se activaelgancho administrativo apropiado o "sinprivilegios".

Loselementosn. ° 1 yn. ° 6 son lasprincipales razonespara usar la API AJAX,en mi opinión. Tieneelnúcleo de WordPress,quees casi seguro quenecesita,ytiene elmismo sistema de seguridad deinicio de sesión que conel resto de WordPress.

1) Why use admin-ajax.php instead of encoding your json in a separate file like themes/example/json.php and encode your data there?

Using admin-ajax.php means that the WordPress Core is loaded and available. WIthout that, you would need to hand load the files you need, which is a complicated process and prone to failure if you don't know the Core very, very well. And, how good are you with Javascript security?

2) How does admin-ajax.php work? I don't understand much from that file. Does it load all the functions so you are ready to use them?

1. It loads the WordPress Core, meaning you can use things like $wpdb and $WP_Query. That is through about line 25.
2. It sends a few headers-- lines 37 - 41.
   
   1. A content type header
   2. A header to tell browsers not to cache the results
   3. The interesting headers are those sent by send_nosniff_headers()
   4. and nocache_headers().
3. The admin_init hook fires.
4. Core actions are defined and registered dynamically-- lines 46 - 73. These won't be registered unless they are needed-- that is, unless they are requested via $_GET or $_POST.
5. The "heartbeat" API hook fires-- line 75
6. The "logged in" status of the requesting user is checked and the appropriate administrative or "no priviledge" hook is fired.

Items #1 and #6 are the primary reasons to use the AJAX API, in my opinion. You have the WordPress Core, which you almost certainly need, and you have the same login security system as with the rest of WordPress.

admin-ajax.phpesparte de la API AJAX de WordPress,y sí,maneja solicitudestanto delbackend como delfront. aquí lo que averiguoparatupreguntaes:

2) ¿Cómofunciona admin-ajax.php?

para la lógica ,puede visita aquí.

Esto supone que ya sabe cómoponeren cola JavaScript,etc.

Pieza de JavaScript:

 jQuery(document).ready(function($) {

    // We'll pass this variable to the PHP function example_ajax_request
    var fruit = 'Banana';

    // This does the ajax request
    $.ajax({
        url: ajaxurl,
        data: {
            'action':'example_ajax_request',
            'fruit' : fruit
        },
        success:function(data) {
            // This outputs the result of the ajax request
            console.log(data);
        },
        error: function(errorThrown){
            console.log(errorThrown);
        }
    });   

});
 

Pieza de PHP:

 function example_ajax_request() {

    // The $_REQUEST contains all the data sent via ajax 
    if ( isset($_REQUEST) ) {

        $fruit = $_REQUEST['fruit'];

        // Let's take the data that was sent and do something with it
        if ( $fruit == 'Banana' ) {
            $fruit = 'Apple';
        }

        // Now we'll return it to the javascript function
        // Anything outputted will be returned in the response
        echo $fruit;

        // If you're debugging, it might be useful to see what was sent in the $_REQUEST
        // print_r($_REQUEST);

    }

    // Always die in functions echoing ajax content
   die();
}

add_action( 'wp_ajax_example_ajax_request', 'example_ajax_request' );

// If you wanted to also use the function for non-logged in users (in a theme for example)
 add_action( 'wp_ajax_nopriv_example_ajax_request', 'example_ajax_request' );
 

1) ¿Por qué usar admin-ajax.phpen lugar de codificar sujsonen un archivo comothemes/example/json.php y codificar sus datos allí?

puede ser útil. admin- ajax.php vsplantilla depáginapersonalizadapara solicitudes Ajax

admin-ajax.php is part of the WordPress AJAX API, and yes, it does handle requests from both backend and front. here what i figure-out for your question that is:

2) How does admin-ajax.php work?

for the logic you can visit here.

This assumes you already know how to enqueue JavaScript, etc.

JavaScript Piece:

jQuery(document).ready(function($) {

    // We'll pass this variable to the PHP function example_ajax_request
    var fruit = 'Banana';

    // This does the ajax request
    $.ajax({
        url: ajaxurl,
        data: {
            'action':'example_ajax_request',
            'fruit' : fruit
        },
        success:function(data) {
            // This outputs the result of the ajax request
            console.log(data);
        },
        error: function(errorThrown){
            console.log(errorThrown);
        }
    });   

});

PHP Piece:

function example_ajax_request() {

    // The $_REQUEST contains all the data sent via ajax 
    if ( isset($_REQUEST) ) {

        $fruit = $_REQUEST['fruit'];

        // Let's take the data that was sent and do something with it
        if ( $fruit == 'Banana' ) {
            $fruit = 'Apple';
        }

        // Now we'll return it to the javascript function
        // Anything outputted will be returned in the response
        echo $fruit;

        // If you're debugging, it might be useful to see what was sent in the $_REQUEST
        // print_r($_REQUEST);

    }

    // Always die in functions echoing ajax content
   die();
}

add_action( 'wp_ajax_example_ajax_request', 'example_ajax_request' );

// If you wanted to also use the function for non-logged in users (in a theme for example)
 add_action( 'wp_ajax_nopriv_example_ajax_request', 'example_ajax_request' );

1) Why use admin-ajax.php instead of encoding your json in a separate file like themes/example/json.php and encode your data there?

may be this helpful.admin-ajax.php vs Custom Page Template for Ajax Requests