Toying with heredocs in PHP, I realized the name of the heredoc does not have to be unique. Thus:
$a = <<<EOD
Some string
EOD;
$b = <<<EOD
A different string
EOD;
is correct and behaves exactly as you would expect.
Is this bad practice for any reason? Why does a heredoc need a name/label (EOD above) at all, since you can't reference it by the name?
What if the string you're specifying contains EOD?
You can select the identifier to avoid conflicts with the chunk of text you're using as a string.
You don't reference it as such, but it acts as an identifier to indicate the end of the heredoc. e.g.
$a = <<<EOD
EOA
EOB
EOC
EOD;
One benefit is that editors like vim can apply syntax highlighting to heredocs named with HTML, EOHTML, EOSQL, EOJAVASCRIPT making them much prettier to work with...
$html = <<<EOHTML
<p class="foo">foo</em>
EOHTML;
$sql = <<<EOSQL
SELECT DISTINCT(name) FROM foo ORDER BY bar;
EOSQL;
$js = <<<EOJAVASCRIPT
foo = { bar: 'bar'; }
EOJAVASCRIPT;
Related
So I have a string from a rendered template that looks like
"Dear {{user_name}},\r\n\r\nThank you for your purchase. If you have any questions, we are happy to help.\r\n\r\n\r\n{{company_name}}\r\n{{company_phone_number}}\r\n"
All those variables like {{user_name}} are optional and do not need to be included but I want to check that if they are, they have {{ in front of the variable name. I am using liquid to parse and render the template and couldn't get it to catch if the user only uses 1 (or no) opening brackets. I was only able to catch the proper number of closing brackets. So I wrote a method to check that if these variables exist, they have the correct opening brackets. It only works, however, if all those variables are found.
here is my method:
def validate_opening_brackets?(template)
text = %w(user_name company_name company_phone_number)
text.all? do |variable|
next unless template.include? variable
template.include? "{{#{variable}"
end
end
It works, but only if all variables are present. If, for example, the template created by the user does not include user_name, then it will return false. I've also done this loop using each, and creating a variable outside of the block that I assign false if the conditions are not met. I would really, however, like to get this to work using the all? method, as I can just return a boolean and it's cleaner.
If the question is about how to rewrite the all? block to make it return true if all present variable names have two brackets before them and false otherwise then you could use something like this:
def validate_opening_brackets?(template)
variables = %w(user_name company_name company_phone_number)
variables.all? do |variable|
!template.include?(variable) || template.include?("{{#{variable}")
end
end
TL;DR
There are multiple ways to do this, but the easiest way I can think of is to simply prefix/postfix a regular expression with the escaped characters used by Mustache/Liquid, and using alternation to check for each of your variable names within the template variable characters (e.g. double curly braces). You can then use String#scan and then return a Boolean from Enumerable#any? based on the contents of the Array returned by from #scan.
This works with your posted example, but there may certainly be other use cases where you need a more complex solution. YMMV.
Example Code
This solution escapes the leading and trailing { and } characters to avoid having them treated as special characters, and then interpolates the variable names with | for alternation. It returns a Boolean depending on whether templated variables are found.
def template_string_has_interpolations? str
var_names = %w[user_name company_name company_phone_number]
regexp = /\{\{#{var_names.join ?|}\}\}/
str.scan(regexp).any?
end
Tested Examples
template_string_has_interpolations? "Dear {{user_name}},\r\n\r\nThank you for your purchase. If you have any questions, we are happy to help.\r\n\r\n\r\n{{company_name}}\r\n{{company_phone_number}}\r\n"
#=> true
template_string_has_interpolations? "Dear Customer,\r\n\r\nThank you for your purchase. If you have any questions, we are happy to help.\r\n\r\n\r\nCompany, Inc.\r\n(555) 555-5555\r\n"
#=> false
I have a YAML file that uses the encoding __firstname__ as a placeholder which signifies that an existing method firstname should be used, rather than the literal string in a subsequent process.
I am trying to understand the most ruby way to to do this. Basically, I need to extract the part between the underscores and send it to an object. Here is pseudocode:
variable = '__firstname__'
if variable is prefixed and suffixed with underscores
result = object.send(variable.removeunderscores)
else
result = variable
end
puts result
I was about to write this procedurally like this, but this is the type of thing that I think ruby can less clunkily if only I knew the language better.
What is a clean why to write this?
There's nothing wrong with verbose code if it's clear to read IMO.
I'd do something like this using String#start_with? and String#end_with?:
variable = '__firstname__'
if variable.start_with?("__") && variable.end_with?("__")
result = object.send(variable[2...-2])
else
result = variable
end
Newbie to Ruby here and I'm trying to figure something out. I've got a situation where I have something like the following:
sql = q%{select foo from bar where var1 = :ugh and var2 = :moreugh}
Now, I can print out variable "sql", but if I just use puts and #{sql} it shows the symbols as above, ":ugh".
I'd like to be able to print out string sql with the values of the symbols displayed rather than the names of the symbols.
Any pointers out there? Many thanks!
your example-code is broken, i assume you want to do a single-quoted-string %q{...}
and that is exactly what you get: one string. so there are no symbols in there, it's just ONE string. similar to '...'
I think, assuming you are using symbols instead of string, You can use following query:
sql = "select foo from bar where var1 = 'ugh' and var2 = 'moreugh'"
So using puts or #{sql} will give you correct output.
Comment in case this doesn't meet your requirement.
You probably want this:
sql = "select foo from bar where var1 = '#{ugh}' and var2 = '#{moreugh}"'
where ugh and moreugh are variables. But, you should do it that way, your system would be open to SQL Injection. Use bind variables in your DB engine instead.
You have two errors. You need to use %Q to enable interpolation, and variables are included in the string in the form #{:ugh}. So, you want:
sql = %Q{select foo from bar where var1 = #{ugh} and var2 = #{moreugh}}
puts sql
But please, please, please don't do this, even just for a small project. You are setting yourself up for a SQL injection attacj.
I can't figure out how to search for text containing single quotes using XPATHs.
For example, I've added a quote to the title of this question. The following line
$x("//*[text()='XQuery looking for text with 'single' quote']")
Returns an empty array.
However, if I try the following
$x("//*[text()=\"XQuery looking for text with 'single' quote\"]")
It does return the link for the title of the page, but I would like to be able to accept both single and double quotes in there, so I can't just tailor it for the single/double quote.
You can try it in chrome's or firebug's console on this page.
Here's a hackaround (Thanks Dimitre Novatchev) that will allow me to search for any text in xpaths, whether it contains single or double quotes. Implemented in JS, but could be easily translated to other languages
function cleanStringForXpath(str) {
var parts = str.match(/[^'"]+|['"]/g);
parts = parts.map(function(part){
if (part === "'") {
return '"\'"'; // output "'"
}
if (part === '"') {
return "'\"'"; // output '"'
}
return "'" + part + "'";
});
return "concat(" + parts.join(",") + ")";
}
If I'm looking for I'm reading "Harry Potter" I could do the following
var xpathString = cleanStringForXpath( "I'm reading \"Harry Potter\"" );
$x("//*[text()="+ xpathString +"]");
// The xpath created becomes
// //*[text()=concat('I',"'",'m reading ','"','Harry Potter','"')]
Here's a (much shorter) Java version. It's exactly the same as JavaScript, if you remove type information. Thanks to https://stackoverflow.com/users/1850609/acdcjunior
String escapedText = "concat('"+originalText.replace("'", "', \"'\", '") + "', '')";!
In XPath 2.0 and XQuery 1.0, the delimiter of a string literal can be included in the string literal by doubling it:
let $a := "He said ""I won't"""
or
let $a := 'He said "I can''t"'
The convention is borrowed from SQL.
This is an example:
/*/*[contains(., "'") and contains(., '"') ]/text()
When this XPath expression is applied on the following XML document:
<text>
<t>I'm reading "Harry Potter"</t>
<t>I am reading "Harry Potter"</t>
<t>I am reading 'Harry Potter'</t>
</text>
the wanted, correct result (a single text node) is selected:
I'm reading "Harry Potter"
Here is verification using the XPath Visualizer (A free and open source tool I created 12 years ago, that has taught XPath the fun way to thousands of people):
Your problem may be that you are not able to specify this XPath expression as string in the programming language that you are using -- this isn't an XPath problem but a problem in your knowledge of your programming language.
Additionally, if you were using XQuery, instead of XPath, as the title says, you could also use the xml entities:
"" for double and ' for single quotes"
they also work within single quotes
You can do this using a regular expression. For example (as ES6 code):
export function escapeXPathString(str: string): string {
str = str.replace(/'/g, `', "'", '`);
return `concat('${str}', '')`;
}
This replaces all ' in the input string by ', "'", '.
The final , '' is important because concat('string') is an error.
Well I was in the same quest, and after a moment I found that's there is no support in xpath for this, quiet disappointing! But well we can always work around it!
I wanted something simple and straight froward. What I come with is to set your own replacement for the apostrophe, kind of unique code (something you will not encounter in your xml text) , I chose //apos// for example. now you put that in both your xml text and your xpath query . (in case of xml you didn't write always we can replace with replace function of any editor). And now how we do? we search normally with this, retrieve the result, and replace back the //apos// to '.
Bellow some samples from what I was doing: (replace_special_char_xpath() is what you need to make)
function repalce_special_char_xpath($str){
$str = str_replace("//apos//","'",$str);
/*add all replacement here */
return $str;
}
function xml_lang($xml_file,$category,$word,$language){ //path can be relative or absolute
$language = str_replace("-","_",$language);// to replace - with _ to be able to use "en-us", .....
$xml = simplexml_load_file($xml_file);
$xpath_result = $xml->xpath("${category}/def[en_us = '${word}']/${language}");
$result = $xpath_result[0][0];
return repalce_special_char_xpath($result);
}
the text in xml file:
<def>
<en_us>If you don//apos//t know which server, Click here for automatic connection</en_us> <fr_fr>Si vous ne savez pas quelle serveur, Cliquez ici pour une connexion automatique</fr_fr> <ar_sa>إذا لا تعرفوا أي سرفير, إضغطوا هنا من أجل إتصال تلقائي</ar_sa>
</def>
and the call in the php file (generated html):
<span><?php echo xml_lang_body("If you don//apos//t know which server, Click here for automatic connection")?>
So here is my problem.
I want to retrieve a string stored in a model and at runtime change a part of it using a variable from the rails application. Here is an example:
I have a Message model, which I use to store several unique messages. So different users have the same message, but I want to be able to show their name in the middle of the message, e.g.,
"Hi #{user.name}, ...."
I tried to store exactly that in the database but it gets escaped before showing in the view or gets interpolated when storing in the database, via the rails console.
Thanks in advance.
I don't see a reason to define custom string helper functions. Ruby offers very nice formatting approaches, e.g.:
"Hello %s" % ['world']
or
"Hello %{subject}" % { subject: 'world' }
Both examples return "Hello world".
If you want
"Hi #{user.name}, ...."
in your database, use single quotes or escape the # with a backslash to keep Ruby from interpolating the #{} stuff right away:
s = 'Hi #{user.name}, ....'
s = "Hi \#{user.name}, ...."
Then, later when you want to do the interpolation you could, if you were daring or trusted yourself, use eval:
s = pull_the_string_from_the_database
msg = eval '"' + s + '"'
Note that you'll have to turn s into a double quoted string in order for the eval to work. This will work but it isn't the nicest approach and leaves you open to all sorts of strange and confusing errors; it should be okay as long as you (or other trusted people) are writing the strings.
I think you'd be better off with a simple micro-templating system, even something as simple as this:
def fill_in(template, data)
template.gsub(/\{\{(\w+)\}\}/) { data[$1.to_sym] }
end
#...
fill_in('Hi {{user_name}}, ....', :user_name => 'Pancakes')
You could use whatever delimiters you wanted of course, I went with {{...}} because I've been using Mustache.js and Handlebars.js lately. This naive implementation has issues (no in-template formatting options, no delimiter escaping, ...) but it might be enough. If your templates get more complicated then maybe String#% or ERB might work better.
one way I can think of doing this is to have templates stored for example:
"hi name"
then have a function in models that just replaces the template tags (name) with the passed arguments.
It can also be User who logged in.
Because this new function will be a part of model, you can use it like just another field of model from anywhere in rails, including the html.erb file.
Hope that helps, let me know if you need more description.
Adding another possible solution using Procs:
#String can be stored in the database
string = "->(user){ 'Hello ' + user.name}"
proc = eval(string)
proc.call(User.find(1)) #=> "Hello Bob"
gsub is very powerful in Ruby.
It takes a hash as a second argument so you can supply it with a whitelist of keys to replace like that:
template = <<~STR
Hello %{user_email}!
You have %{user_voices_count} votes!
Greetings from the system
STR
template.gsub(/%{.*?}/, {
"%{user_email}" => 'schmijos#example.com',
"%{user_voices_count}" => 5,
"%{release_distributable_total}" => 131,
"%{entitlement_value}" => 2,
})
Compared to ERB it's secure. And it doesn't complain about single % and unused or inexistent keys like string interpolation with %(sprintf) does.