What is the right way to mount interfaces on PHP pages?

Question

In several projects I have seen around, where it is necessary to consult databases to obtain information, and later to assemble tables, I noticed the following approach presented in the code snippet below:

<?php
    while($row = mysql_fetch_array($res)) {
?>
    <tr>
        <td><?php echo $row['nome']; ?></td>
        <td><?php echo $row['idade']; ?></td>
        <td><?php echo $row['dia']; ?></td>
        <td><?php echo $row['turno']; ?></td>
    </tr>
<?php
    }
?>

In it, one opens several times <?php ?> to extract information from the bank, and assemble the page.

This does not seem correct, it would not be better to use javascript(ajax) to retrieve information, and then DOM to assemble the page?

My question is what would be the best way to build pages where it is necessary to query databases for information.

Answer 1

There is nothing wrong with opening and closing tags to compose HTML content.

Everything that is delimited by the PHP tag is parsed by the PHP compiler.

If you pass things not related to PHP, this has an extra cost for the compiler to process the data.

Let’s take an example:

echo '<table><tr><td>'.$variavel.'</td></tr></table>';

Here in this example, PHP will just "spit" back the static chunk <table><tr><td> and </td></tr></table>.

That is, sent to the compiler to process a text that does not have to be processed. It is static information. PHP had to read this information, increasing memory consumption and processing.

Otherwise,

<table><tr><td><?php echo $variavel;?></td></tr></table>

The compiler will only receive the snippet $variavel;.

What would be a bad practice, is something like this

<?php
echo $variavel;
?>
<?php
echo $outra_variavel;

function alguma_coisa() {
    return null;
}

echo alguma_coisa();
?>

Here in this case yes, we even have a problem because it closed and opened unnecessarily because the following code is also PHP. Could just continue on the same tag

<?php
echo $variavel;

echo $outra_variavel;

function alguma_coisa() {
    return null;
}

echo alguma_coisa();
?>

Also, in doing

?>
<?php

It is generating an output that is usually the common cause among beginners with the famous "header already sent". But I’m not going into this subject because it’s more extensive and distracts from the focus of the issue.

Escaping quotes

A difficulty when going through all PHP is having to escape characters:

echo '<tr><td>texto com aspa simples \''.$variavel.'</td></tr>';

Can be solved using double quote

echo "<tr><td>texto com aspa simples '".$variavel."</td></tr>";

But this also depends a lot on the code pattern of the project. I particularly use single quote and there are those who prefer double quote. This is a matter of opinion and somewhat controversial. However, even with double quote falls into the same trap when the static text has double quote. You have to make the escape:

echo "<tr><td>texto com aspa dupla \"".$variavel."</td></tr>";

So far are very simple examples. In real life you will have things like this

lorem ipsum single quot'e double "quote"
<b>
<script>
var str = "foo'bar";
document.write(str);
</script>
<?php echo $variavel_do_php;?>
</b>

This is still a kid’s level... but it’s just to illustrate

See how it looks otherwise:

echo '
lorem ipsum single quot\'e double "quote"
<b>
<script>
var str = "foo\'bar";
document.write(str);
</script>
'.$variavel_do_php.'
</b>';

Tell me which of the two is best for code reading?

In terms of performance, they make no difference. So I usually choose the one that’s simplest and readable and, of course, it all depends on the purpose of use and that’s what matters most.

Javascript Template

Regarding the use of Javascript to assemble the view, the requirements of the project must be evaluated. If it is a web project, usually a website has to be SEO compatible. If you assemble the pages via Javascript you will have problems with SEO because the search engines do not interpret Javascript.

The layout montage scheme with Javascript was much used in the past before the "Google Age". It was very common for websites to assemble the content of pages with Javascript because it greatly reduces the HTML code. Unfortunately all were forced to increase redundant content on the pages due to SEO.

It is currently used more for private projects, intranets or even websites that don’t care about SEO.

MVC

If you analyze the question code for an MVC project, we can say that it is not a good practice because in MVC it usually does not invoke PHP functions directly in the View. It is usually using a template engine, helpers, etc.

In short

I have highlighted only obvious points. And there are still many other points to mention but this makes the subject too extensive.

In general, avoid thinking of "what is best for X or Y?". See this question as "what is best for project X or situation Y?". Because there is nothing that is "the universal solution". There are several solutions that are better suited to a given situation.

Minimizing the visual dirt

For those who care about the use of <?php echo $variavel;?>, it is possible to reduce using short tag.

The equivalent of this <?php echo $variavel;?> can be written as <?=$variavel;?>

Remembering that there was a time when the elimination of the short tag was considered. At that time, as a precaution, I stopped using. A while later they went back and decided to keep but I still avoid using it as a precaution. But this is a personal choice. I don’t mean you should think the same.

The use of <?php is recommended to avoid confusion with XML documents that also use <? tag.

<?xml version="1.0" encoding="UTF-8"?>
<note>
  <to>Tove</to>
  ....