I have a system_settings table which has a key and value columns. The key looks something like general.site.something.config and the value is a simple string.
I'd like to have a static class which, upon initialization, reads the settings and caches the values. Furthermore, I'd like to be able to access the settings in an OO way, such as SystemSetting.CACHE.General.Site.Something.Config in order to pull back the value for that key. Basically turning the rows in the table into a tree.
Is there an easy way to do this in Ruby 1.8.7?
TL;DR, No. No easy (read 'built-in') way atleast.
The syntax you want is not the way things happen in Ruby (without over-plumbing, that is). To have a look at the over-plumbing I'm referring to, have a look at the code I wrote for this example that demonstrates some of the desired functionality you want. I wouldn't suggest using it though and that's the same reason I'm not posting it here.
Related
I would like to ask what consideration is the immutableOpenmap in Elasticsearch designed for? What kind of utility does it have? It is used in both aliasmetadata and indexmetadata. My personal guess is that it has something to do with atomicity, but I don't get the full understanding from the code.
From the source
An immutable map implementation based on open hash map.
Immutable simply means that once you create it, you cannot modify its content anymore. All methods that would mutate the content, whether keys or values, will throw UnsupportedOperationException.
Is it possible, using the AWS Ruby SDK (or just DynamoDB in general), to get an item or items from a table that uses a primary key only, and where that primary key ends with a certain string?
I haven't come across anything in the docs that explicitly answers this question, either in the ruby ddb docs or the general docs for ddb. I'm not saying the question is not answered, but if it is, I can't find it.
If it is possible, could someone provide an example for ruby or link to the docs where an example exists?
Although #Ryan is correct and this can be done with query, just bear in mind that you're doing a "full-table-scan" here. That might be OK for a one-time job but probably not the best practice for a routine task (and of course not as a part of your API calls).
If your use-case involves quickly finding objects based on their suffix in a specific field, consider extracting this suffix (assuming it's a fixed-size suffix) as another field and have a secondary index on that one. If you want to query arbitrary length suffixes, I would create a lookup table and update it with possible suffixes (or some of them, to save some calls, and then filter when querying).
It looks like you would want to use the Query method on the SDK to find the items your looking for. It seems that "EndsWith" is not available as a comparison operator in the SDK though. So you would need to use CONTAINS and then check your results locally.
This should lead to the best performance, letting DynamoDb do the initial heavy lifting and then further pruning the results once you receive them.
http://docs.aws.amazon.com/sdkforruby/api/Aws/DynamoDB/Client.html#query-instance_method
Is there a data structure within LiveCode that can be used as a "holder" for associated data, letting me handle it collectively? I come from a Java / Javascript / C background so I am looking for a Class or Struct sort of data structure.
I've found examples of Groups, which seem to have some of this functionality, but it feels a bit like I'm bending the language to meet my needs.
As a specific example, suppose I had an image field on my screen that would randomly display an image and, when pressed, play an associated sound clip. I'd expect to create a list of "structures" that contained the path to the image and the path to the associated sound clip, and use that data to populate the image field and to decide what sound clip to play.
Would a Group be the correct structure to use in this case? Or am I approaching this in a way that isn't really fitting with the way LiveCode works?
It takes a little getting used to, but the xTalk world is much simpler and more open than any ordinary procedural language. So much of what you once had to manage is no longer required.
So when splash21 said that you could store all your image and sound references in a custom property, he was really saying that the LiveCode environment contains intrinsic, high level functionality that makes these sorts of things instantly accessible, and the only thing required of you is to call for them, and they simply work.
The only way to appreciate this is to make a few simple programs, to really see what is possible. Make your application. Everything you mentioned can be accomplished with perhaps a dozen lines of code in a single handler. I recommend that you join the LiveCode use list and forums. The community is vibrant and eager to help, frequently with full blown solutions to specific problems, but more importantly, as guides and mentors to new users
Craig Newman
Arrays in LiveCode are actually associative arrays (like hash maps). A key is associated with a value. The value might be as well an array.
Chapter 5.5.7 of the User's Guide says
Array elements may contain nested or sub-elements, making them multi-dimensional.
This type of array is ideal for processing hierarchical data structures such as trees or
XML. To access a sub-element, simply declare it using an additional set of square
brackets.
put "ABC" into myVariable["myKeyName"][“aChildElement”]
see also
How to store pictures in a stack?
Dave- I'm hoping to get a struct-like container implemented in the near future. Meanwhile you can, as splash21 mentioned, use custom properties (or better yet, custom property sets) to do what you want. This will give you a pseudo-struct for each object and you can implement the file and sound specifications into the properties. And if you use that in conjunction with a behavior object you'll end up very close to a real inheritable class formation.
I need to edit some cfg files for an application, but the thing is the application wont start if I do since it must match. I dont have the sources of the application.
I guess if the hash doesnt match the hash of the exe, it exits.
Could you bypass this somehow?
Actually, there is a way:
while(hash of malicious config file does not match original)
{
make random, non-functional change to malicious config file.
}
This might take a while.
With cretain hash algorithms, you can append data to the end of a file (if an xml file, say, inside comment tags). But its probably more trouble than its worth. E.g., http://www.schneier.com/blog/archives/2005/06/more_md5_collis.html
If the program uses a good hash, it will be difficult to change without breaking the hash. Some applications use relatively poor hashes. It's relatively easy, for example, to edit a file without affecting a CRC-32 if you can afford to set 32 bits of the file to arbitrary values. Any idea what sort of hash function is used?
You can have the app quit checking, but no, there is no way to duplicate a crypto hash of an existing file. That's the point.
Does a file exist having your desired settings and with the same hash? possibly
Will you be able to find it? Almost certainly not
It's time to break out your disassembler and pull apart the application to get rid of the hash check I'm afraid. No other solution will do what you want in a timely manner.
This kind of validation is intentionally difficult to circumvent. Hashes generally work such that small changes in the input produce widely varied output. The check in this case is doing its duty, unfortunately for your situation.
Although in theory there are other inputs that hash to the same thing, they'll be very different from your input, not just a little different. Finding these inputs will also be as time-consuming and difficult as hacking encrypted data. So basically, no.
As some other posts have mentioned, if you are adventurous and life and death are at stake, you could disassemble the application binary and actually remove the machine language check for the hash. This is varsity-ninja work though.
Am wondering if the combination of trim(), strip_tags() and addslashes() is enough to filter values of variables from $_GET and $_POST
That depends what kind of validation you are wanting to perform.
Here are some basic examples:
If the data is going to be used in MySQL queries make sure to use mysql_real_escape_query() on the data instead of addslashes().
If it contains file paths be sure to remove the "../" parts and block access to sensitive filename.
If you are going to display the data on a web page, make sure to use htmlspecialchars() on it.
But the most important validation is only accepting the values you are expecting, in other words: only allow numeric values when you are expecting numbers, etc.
Short answer: no.
Long answer: it depends.
Basically you can't say that a certain amount of filtering is or isn't sufficient without considering what you want to do with it. For example, the above will allow through "javascript:dostuff();", which might be OK or it might not if you happen to use one of those GET or POST values in the href attribute of a link.
Likewise you might have a rich text area where users can edit so stripping tags out of that doesn't exactly make sense.
I guess what I'm trying to say is that there is simple set of steps to sanitizing your data such that you can cross it off and say "done". You always have to consider what that data is doing.
It highly depends where you are going to use it for.
If you are going to display things as HTML, make absolutely sure you are properly specifying the encoding (e.g.: UTF-8). As long as you strip all tags, you should be fine.
For use in SQL queries, addslashes is not enough! If you use the mysqli library for example, you want to look at mysql::real_escape_string. For other DB libraries, use the designated escape function!
If you are going to use the string in javascript, addslashes will not be enough.
If you are paranoid about browser bugs, check out the OWASP Reform library
If you use the data in another context than HTML, other escaping techniques apply.