PHP Function and variables stored in a string in a database

Question

I need to store data within a database, when I get the data from the database I need functions and variables in the string to be worked out as such.

Example

$str = "<p>Dear {$this->name},</p>"

I then store this in the database, and when I retrieve the string and run it through

eval("\$detail= \"$detail\";");

then the variable gets populated with the name. This is exactly what I needed and works fine.

The problem is I want to run a function with this variable as the parameter.

example. I would like to ucwords the variable.

I have tried:

$str = "<p>Dear {ucwords($this->name)},</p>"  //just echoed {ucword(->name)},
$str = "<p>Dear {ucwords($this->name)},</p>"  //Fatal error: Function name must be a string,

Am I going in the right direction? Is this at all possible?

@hsz eval() isn't inherently evil, but it's very easy to misuse/overuse. — Wiseguy
– Wiseguy, Commented Jan 9, 2013 at 15:04
first tim ei have used eval, i couldn't see any other way of having dynamic variables called from database? — Liam
– Liam, Commented Jan 9, 2013 at 15:12

Alex Amiryan · Accepted Answer · 2013-01-09 15:02:02Z

3

You don't need to keep PHP code in database. This is a bad practice and also can lead to security vulnerabilities.

Instead store in database string like this:

<p>Dear [name],</p>

And when you retrieve it you can just do:

$stringFromDb = str_replace("[name]", $this->name, $stringFromDb);

or

$stringFromDb = str_replace("[name]", ucwords($this->name), $stringFromDb);

Other common approach is to use sprintf. So you need to store in database string with %s as placeholders for values.

Example:

<p>Dear %s,</p>

and replace with

$stringFromDb = sprintf($stringFromDb, ucwords($this->name));

edited Jan 9, 2013 at 15:02

answered Jan 9, 2013 at 14:56

Alex Amiryan

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4 Comments

Liam Over a year ago

Hiya thanks for the reply. The problem is that i am will be creating a GUI for the database. This will allow the user to input any variable to be in the string. My model and related models have many variables

Liam Over a year ago

wow this site is so quick, thanks for the help. Ok, the issue is i wont know what variables the user have put into the string (email)

Liam Over a year ago

say for eg. The email could have $this->name, $this->balance, $this->street.

Alex Amiryan Over a year ago

If you are building UI for your database then definitely you don't want PHP codes there, because it is a total mess. How you would explain to users what kind of variables you have in your code available for evaluation? I would suggest defining list of things that can be inserted into texts (like: [name], [email], [tel], etc) and build combo box with this values and offer convenient way for inserting them into text.

AKX · Accepted Answer · 2013-01-09 15:26:19Z

What you seem to be looking for is a simple templating language.

It's been a long while since I've written PHP (and I suddenly remember why...), but here's something I whipped up.

It should support both objects ($a->name) and arrays ($a["name"]) as input objects.

You can add new filters (name -> function name mapping) in $valid_filters.

$valid_filters = array("title" => "ucfirst", "upper" => "strtoupper");

function _apply_template_helper($match) {
  global $_apply_template_data, $valid_filters;
  $var = $match[1];
  $filter = $valid_filters[trim($match[2], ':')];
  $value = is_array($_apply_template_data) ? $_apply_template_data[$var] : $_apply_template_data->$var;
  if($filter && !empty($value)) $value = call_user_func($filter, $value);
  return !empty($value) ? $value : $match[0];
}

function apply_template($template, $data) {
  global $_apply_template_data;
  $_apply_template_data = $data;
  $result = preg_replace_callback('/\{\{(.+?)(:.+?)?\}\}/', "_apply_template_helper", $template);
  $_apply_template_data = null;
  return $result;
}

How to use it:

$template = "Hello {{name:title}}, you have been selected to win {{amount}}, {{salutation:upper}}";
echo apply_template($template, array("name"=>"john", "amount" => '$500,000', "salutation" => "congratulations"));

The result:

Hello John, you have been selected to win $500,000, CONGRATULATIONS

Liam · Accepted Answer · 2013-01-09 15:11:46Z

0

I have found the following works,

If i contain the function within the class itself then it can be called using the following code

<p>Dear {\$this->properCase(\$this->rl_account->name)},</p>

But i would like to be able to do this now without having the database have the code as Alex Amiryan mentions earlier.

answered Jan 9, 2013 at 15:11

Liam

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