I use FetchAPI of Fable.PowerPack to make basic authentication application, but I am in trouble because I can not base64 encode.
For example, I wrote such a code,
let base64enc str =
str
|> Seq.map byte
|> Array.ofSeq
|> System.Convert.ToBase64String
However, the following error occurs.
Error FABLE: Can not find replacement for System.Convert.ToBase64String
Is there any way?
I think the JavaScript btoa function does what you need. The easiest and quickest way to make it available in Fable is to use the Emit attribute:
[<Emit("btoa($0)")>]
let toBase64String (bytes:byte[]) : string = failwith "JS"
There might be some slight differences between the .NET method and the JS function, in which case you'll probably need to reimplement those on your own.
Also, this sounds like a thing that Fable could support - the replacements for .NET operations are generally defined in the Replacements.fs file and if you were interested in sending a pull request to add mapping for ToBase64String and others, that would be amazing!
Related
Because I am rewriting a legacy app, I cannot change what the clients either send or accept. I have to accept and return JSON, HTML, and an in-house XML-like serialization.
They do, fortunately set headers that describe what they are sending and what they accept.
So right now, what I do is have a decoder module and an encoder module with methods that are basically if/elif/else chains. When a route is ready to process/return something, I call the decoder/encoder module with the python object and the header field, which returns the formatted object as a string and the route processes the result or returns Response().
I am wondering if there is a more Quart native way of doing this.
I'm also trying to figure out how to make this work with Quart-Schema. I see from the docs that one can do app.json_encoder = <class> and I suppose I could sub in a different processor there, but it seems application global, there's no way to set it based on what the client sends. Optimally, it would be great if I could just pass the results of a dynamically chosen parser to Quart-Schema and let it do it's thing on python objects.
Thoughts and suggestions welcome. Thanks!
You can write your own decorator like the quart-schema #validation_headers(). Inside the decorator, check the header for the Content-Type, parse it, and pass the parsed object to the func(...).
Ive been searching through source for a while, and it appears to me that there are no given Rails tools for retrieving the String representation of various HTML content types. Ive also found this to be a very difficult concept to search for in general.
What I want is something like this:
Mime::Mimes::CONTENT_TYPE_JSON = 'application/json'.freeze
or, Mime::Mimes::CONTENT_TYPES[:json] etc.
...because I want to do a lot of things like some_value == 'application/json' or some_value = 'application/json' etc.
I want to use the expression "application/json" often, and I dont want to create new String instances for something that is pretty well within the domain of web application development. Ive thought of creating my own app consts or vars so I dont have to allocate HTML Content Type strings more than once, but also feel this should just be available for me in any web application framework (at least, those written in languages where every string is a new memory allocation).
Is there a better tool or resource within the Rails 5 source that I am missing that allows easy retrieval of content type strings? Do I have to get a gem / create my own for this?
Note: Im away of how heavy of an "optimization" this may appear to be. Let's then entertain this query from a position of being pragmatic about organizational style, for a project that requires elimination of any duplication of domain-specific string literals, and to keep them symbolized or as some frozen const. Let's pretend its a personal project for the sheer joy of experimenting with such style!
There is a shorthand for it:
Mime[:json]
Mime#[] -
https://github.com/rails/rails/blob/e2efc667dea886e71c33e3837048e34b7a1fe470/actionpack/lib/action_dispatch/http/mime_type.rb#L41
which uses
Mime::Type#lookup_by_extension -
https://github.com/rails/rails/blob/e2efc667dea886e71c33e3837048e34b7a1fe470/actionpack/lib/action_dispatch/http/mime_type.rb#L149
If you want to get the actual content type you might need to call a #to_s on it:
Mime[:json].to_s
Creating a new module to facilitate simple storage and retrieval using the ActionPack Mime::Type system would work as follows:
# Build hash of type name to value, e.g., { xml: "application/xml" }
CONTENT_TYPES = {}.tap do |simple_content_types_hash|
# Get each registered Mime Type
Mime::EXTENSION_LOOKUP.each do |mime|
simple_content_type_hash[mime.first.to_sym] = mime.last.instance_variable_get("#string").freeze
end
end.freeze
Note: the above is untested, its just a generalization of what I am looking for. Thanks to #Fire-Dragon-DoL for the tip.
This could be added via an initializer, patched into an existing module, or into a new helper module.
I'd like to get position information using the positional parser and Positional trait. I'd like to read the file Im parsing into a string (or something I can convert to a string) and then parse it while retaining the position information. Here's what I've found on 'positional':
https://wiki.scala-lang.org/display/SW/Parsing
...which off-handedly mentions StreamReader and CharArrayReader. Are there other options? Reading my file into something that can be used with a CharArrayReader may be what I need. If so, how does that work? If not, what should I be doing?
(FYI, StreamReader is out because I want to read and keep the file long before I parse it, not because I want to waste memory.)
Direct your favorite browser to the ScalaDoc HTML and navigate to the package scala.util.parsing.input where you'll find the available positioned readers:
CharArrayReader
CharSequenceReader
PagedSeqReader
StreamReader
Addendum
Creating one of these readers, CharArrayReader, e.g., is simple:
val car = new CharArrayReader("sample input")
Now you have the Reader to feed your parser.
Suppose I have this code:
(handler-case (read ...)
(parse-error (condition)
(format t "What text was I reading last to get this error? ~s~&"
(how-to-get-this-text? condition))))
I can only see the parse-namestring accessors, but it gives the message of the error, not the text it was parsing.
EDIT
In my case the problem is less generic, so an alternative solution not involving the entire string that failed to parse can be good too.
Imagine this example code I'm trying to parse:
prefix(perhaps (nested (symbolic)) expressions))suffix
In some cases I need to stop on "suffix" and in others, I need to continue, the suffix itself has no other meaning but just being an indicator of the action the parser should take next.
READ parses from a stream, not a string. The s-expression can be arbitrarily long. Should READ keep a string of what's been read?
What you might need is a special stream. In standard Common Lisp there is no mechanism for user defined streams. But in real life every implementation has such extensible streams. See for example 'gray streams'.
http://www.sbcl.org/1.0/manual/Gray-Streams.html
There's no standard function to do it. You might be able to brute-force something with read-from-string, but whatever you do, it will require some extra work.
I would like to parse standard security expressions like hasRole etc. to get their value in a variable (in a JSP). How can I do that? SpelExpressionParser is the standard EL parser, but I don't think it will parse the security expression.
The simpliest approach is to use a <sec:authorize> tag and modify a desired variable inside its body.
If you actually want to evaluate expressions manually, look at the source of AuthorizeTag - it gets the first bean of type WebSecurtyExpressionHandler from the web application context and uses it to obtain ExpressionParser and EvaluationContext.
I've posted an answer in this topic here - How to parse spring security expressions programmatically. I think this answers your question also.