I've been banging my head against the time crate for the last two days. I can't find, where in their documentation how to take a RFC3339 UTC 2022-12-28T02:11:46Z timestamp and convert that to local time for America/New_York (2022-12-27T21:11:46). I stepped away from using the chrono crate on advise that there is/was a vulnerability and it's not very well maintained as it once was. Chrono also depends on time but in the 0.1.x branch of it.
My cargo.toml includes the line time = { version = "0.3", features = ["macros", "parsing", "local-offset"] } so enable the features I think I need.
use time::{format_description::well_known::Rfc3339, PrimitiveDateTime};
/// The paramater zulu would be a RFC3339 formatted string.
///
/// ```
/// #use time::{format_description::well_known::Rfc3339, PrimitiveDateTime};
/// assert_eq!("2022-12-27T21:11:46", date_time_local("2022-12-28T02:11:46Z".to_string()));
/// ```
fn date_time_local(zulu: &String) -> String {
match PrimitiveDateTime::parse(zulu, &Rfc3339) {
Ok(local) => local.to_string(),
Err(..) => zulu.to_owned(),
}
}
I'm having no such luck here.
fn main() {
assert_eq!("2022-12-27 21:11:46", date_time_local(&"2022-12-28T02:11:46Z".to_string()));
}
/// The parameter zulu should be a RFC3339 formatted string.
/// This converts that Zulu timestamp into a local timestamp.
/// ```
/// assert_eq!("2022-12-27 21:11:46", date_time_local("2022-12-28T02:11:46Z".to_string()));
/// ```
fn date_time_local(zulu: &String) -> String {
use time::{format_description::well_known::Rfc3339, PrimitiveDateTime, UtcOffset};
// Determine Local TimeZone
let utc_offset = match UtcOffset::current_local_offset() {
Ok(utc_offset) => utc_offset,
Err(..) => return zulu.to_owned(),
};
// Parse the given zulu paramater.
let zulu_parsed = match PrimitiveDateTime::parse(zulu, &Rfc3339) {
Ok(zulu_parsed) => zulu_parsed.assume_utc(),
Err(..) => return zulu.to_owned(),
};
// Convert zulu to local time offset.
let parsed = zulu_parsed.to_offset(utc_offset);
format!(
"{:04}-{:02}-{:02} {:02}:{:02}:{:02}",
parsed.year(),
parsed.month() as u8,
parsed.day(),
parsed.hour(),
parsed.minute(),
parsed.second()
)
}
With a slight change that I removed the T between the date and the time.
Related
I wanted to be able to retrieve the content from an attribute like this:
#[foreign_key(table = "some_table", column = "some_column")]
This is how I am trying:
impl TryFrom<&&Attribute> for EntityFieldAnnotation {
type Error = syn::Error;
fn try_from(attribute: &&Attribute) -> Result<Self, Self::Error> {
if attribute.path.is_ident("foreign_key") {
match attribute.parse_args()? {
syn::Meta::NameValue(nv) =>
println!("NAME VALUE: {:?}, {:?}, {:?}",
nv.path.get_ident(),
nv.eq_token.to_token_stream(),
nv.lit.to_token_stream(),
),
_ => println!("Not interesting")
}
} else {
println!("No foreign key")
}
// ... More Rust code
}
Everything works fine if I just put in there only one NameValue. When I add the comma,
everything brokes.
The only error:
error: unexpected token
How can I fix my logic to enable the possibility of have more than just one NameValue?
Thanks
UPDATE: While writing this answer, I had forgotten that Meta has List variant as well which gives you NestedMeta. I would generally prefer doing that instead of what I did in the answer below for more flexibility.
Although, for your particular case, using Punctuated still seems simpler and cleaner to me.
MetaNameValue represents only a single name-value pair. In your case it is delimited by ,, so, you need to parse all of those delimited values as MetaNameValue instead.
Instead of calling parse_args, you can use parse_args_with along with Punctuated::parse_terminated:
use syn::{punctuated::Punctuated, MetaNameValue, Token};
let name_values: Punctuated<MetaNameValue, Token![,]> = attribute.parse_args_with(Punctuated::parse_terminated).unwrap(); // handle error instead of unwrap
Above name_values has type Punctuated which is an iterator. You can iterate over it to get various MetaNameValue in your attribute.
Updates based on comments:
Getting value out as String from MetaNameValue:
let name_values: Result<Punctuated<MetaNameValue, Token![,]>, _> = attr.parse_args_with(Punctuated::parse_terminated);
match name_values {
Ok(name_value) => {
for nv in name_value {
println!("Meta NV: {:?}", nv.path.get_ident());
let value = match nv.lit {
syn::Lit::Str(v) => v.value(),
_ => panic!("expeced a string value"), // handle this err and don't panic
};
println!( "Meta VALUE: {:?}", value )
}
},
Err(_) => todo!(),
};
I am trying to write a mail filter in Rust using the milter crate. I built the example on a Linux VM and it all works fine. However, the example is using u32 as the type of context injected into their handlers, a quite simple example. I instead need to store a string from the handle_header callback through to the handle_eom handler so I can use an incoming header to set the envelope from.
If I log the value of the header in handle_header to console, it writes correctly but by the time it arrives in handle_eom, it has been corrupted/overwritten whatever. I thought that context was supposed to be specifically for this scenario but it seems weird that it uses type inference rather than e.g. a pointer to an object that you can just assign whatever you want to it.
Is my understanding of context wrong or is the code incorrect?
I tried using value and &value in handle_header and it behaves the same way.
use milter::*;
fn main() {
Milter::new("inet:3000#localhost")
.name("BounceRewriteFilter")
.on_header(header_callback)
.on_eom(eom_callback)
.on_abort(abort_callback)
.actions(Actions::ADD_HEADER | Actions::REPLACE_SENDER)
.run()
.expect("milter execution failed");
}
#[on_header(header_callback)]
fn handle_header<'a>(mut context: Context<&'a str>, header: &str, value: &'a str) -> milter::Result<Status> {
if header == "Set-Return-Path" {
match context.data.borrow_mut() {
Some(retpath) => *retpath = &value,
None => {
context.data.replace(value)?;
}
}
}
Ok(Status::Continue)
}
#[on_eom(eom_callback)]
fn handle_eom(mut context: Context<&str>) -> milter::Result<Status> {
match context.data.take() {
Ok(result) => {
println!("Set-return-path header is {}", result.unwrap());
context.api.replace_sender(result.unwrap(), None::<&str>)?;
}
Err(_error) => {}
}
Ok(Status::Continue)
}
Thanks to glts on Github, the author of the crate, the problem was that the string slices passed into the handle_header method were not borrowed by the external code that stores the data pointer so by the time that handle_eom is called, the memory has been reused for something else.
All I had to do was change Context<&str> to Context<String> and convert the strings using mystr.to_owned() and in the reverse direction val = &*mystring
I'm writing a program in Rust that creates a file at a user-defined path. I need to be able to normalize intermediate components (~/ should become $HOME/, ../ should go up a directory, etc.) in order to create the file in the right place. std::fs::canonicalize does almost exactly what I want, but it panics if the path does not already exist.
Is there a function that normalizes componenets the same way as std::fs::canonicalize but doesn't panic if the file doesn't already exist?
There are good reasons such a function isn't standard:
there's no unique path when you're dealing with both links and non existing files. If a/b is a link to c/d/e, then a/b/../f could either mean a/f or c/d/f
the ~ shortcut is a shell feature. You may want to generalize it (I do), but that's a non obvious choice, especially when you consider ~ is a valid file name in most systems.
This being said, it's sometimes useful, in cases those ambiguities aren't a problem because of the nature of your application.
Here's what I do in such a case:
use {
directories::UserDirs,
lazy_regex::*,
std::path::{Path, PathBuf},
};
/// build a usable path from a user input which may be absolute
/// (if it starts with / or ~) or relative to the supplied base_dir.
/// (we might want to try detect windows drives in the future, too)
pub fn path_from<P: AsRef<Path>>(
base_dir: P,
input: &str,
) -> PathBuf {
let tilde = regex!(r"^~(/|$)");
if input.starts_with('/') {
// if the input starts with a `/`, we use it as is
input.into()
} else if tilde.is_match(input) {
// if the input starts with `~` as first token, we replace
// this `~` with the user home directory
PathBuf::from(
&*tilde
.replace(input, |c: &Captures| {
if let Some(user_dirs) = UserDirs::new() {
format!(
"{}{}",
user_dirs.home_dir().to_string_lossy(),
&c[1],
)
} else {
warn!("no user dirs found, no expansion of ~");
c[0].to_string()
}
})
)
} else {
// we put the input behind the source (the selected directory
// or its parent) and we normalize so that the user can type
// paths with `../`
normalize_path(base_dir.join(input))
}
}
/// Improve the path to try remove and solve .. token.
///
/// This assumes that `a/b/../c` is `a/c` which might be different from
/// what the OS would have chosen when b is a link. This is OK
/// for broot verb arguments but can't be generally used elsewhere
///
/// This function ensures a given path ending with '/' still
/// ends with '/' after normalization.
pub fn normalize_path<P: AsRef<Path>>(path: P) -> PathBuf {
let ends_with_slash = path.as_ref()
.to_str()
.map_or(false, |s| s.ends_with('/'));
let mut normalized = PathBuf::new();
for component in path.as_ref().components() {
match &component {
Component::ParentDir => {
if !normalized.pop() {
normalized.push(component);
}
}
_ => {
normalized.push(component);
}
}
}
if ends_with_slash {
normalized.push("");
}
normalized
}
(this uses the directories crate to get the home in a cross-platform way but other crates exist and you could also just read the $HOME env variable in most platforms)
I'm learning rust and trying to make a find like utility (yes another one), im using clap and trying to support command line and config file for the program's parameters(this has nothing to do with the clap yml file).
Im trying to parse the commands and if no commands were passed to the app, i will try to load them from a config file.
Now I don't know how to do this in an idiomatic way.
fn main() {
let matches = App::new("findx")
.version(crate_version!())
.author(crate_authors!())
.about("find + directory operations utility")
.arg(
Arg::with_name("paths")
...
)
.arg(
Arg::with_name("patterns")
...
)
.arg(
Arg::with_name("operation")
...
)
.get_matches();
let paths;
let patterns;
let operation;
if matches.is_present("patterns") && matches.is_present("operation") {
patterns = matches.values_of("patterns").unwrap().collect();
paths = matches.values_of("paths").unwrap_or(clap::Values<&str>{"./"}).collect(); // this doesn't work
operation = match matches.value_of("operation").unwrap() { // I dont like this
"Append" => Operation::Append,
"Prepend" => Operation::Prepend,
"Rename" => Operation::Rename,
_ => {
print!("Operation unsupported");
process::exit(1);
}
};
}else if Path::new("findx.yml").is_file(){
//TODO: try load from config file
}else{
eprintln!("Command line parameters or findx.yml file must be provided");
process::exit(1);
}
if let Err(e) = findx::run(Config {
paths: paths,
patterns: patterns,
operation: operation,
}) {
eprintln!("Application error: {}", e);
process::exit(1);
}
}
There is an idiomatic way to extract Option and Result types values to the same scope, i mean all examples that i have read, uses match or if let Some(x) to consume the x value inside the scope of the pattern matching, but I need to assign the value to a variable.
Can someone help me with this, or point me to the right direction?
Best Regards
Personally I see nothing wrong with using the match statements and folding it or placing it in another function. But if you want to remove it there are many options.
There is the ability to use the .default_value_if() method which is impl for clap::Arg and have a different default value depending on which match arm is matched.
From the clap documentation
//sets value of arg "other" to "default" if value of "--opt" is "special"
let m = App::new("prog")
.arg(Arg::with_name("opt")
.takes_value(true)
.long("opt"))
.arg(Arg::with_name("other")
.long("other")
.default_value_if("opt", Some("special"), "default"))
.get_matches_from(vec![
"prog", "--opt", "special"
]);
assert_eq!(m.value_of("other"), Some("default"));
In addition you can add a validator to your operation OR convert your valid operation values into flags.
Here's an example converting your match arm values into individual flags (smaller example for clarity).
extern crate clap;
use clap::{Arg,App};
fn command_line_interface<'a>() -> clap::ArgMatches<'a> {
//Sets the command line interface of the program.
App::new("something")
.version("0.1")
.arg(Arg::with_name("rename")
.help("renames something")
.short("r")
.long("rename"))
.arg(Arg::with_name("prepend")
.help("prepends something")
.short("p")
.long("prepend"))
.arg(Arg::with_name("append")
.help("appends something")
.short("a")
.long("append"))
.get_matches()
}
#[derive(Debug)]
enum Operation {
Rename,
Append,
Prepend,
}
fn main() {
let matches = command_line_interface();
let operation = if matches.is_present("rename") {
Operation::Rename
} else if matches.is_present("prepend"){
Operation::Prepend
} else {
//DEFAULT
Operation::Append
};
println!("Value of operation is {:?}",operation);
}
I hope this helps!
EDIT:
You can also use Subcommands with your specific operations. It all depends on what you want to interface to be like.
let app_m = App::new("git")
.subcommand(SubCommand::with_name("clone"))
.subcommand(SubCommand::with_name("push"))
.subcommand(SubCommand::with_name("commit"))
.get_matches();
match app_m.subcommand() {
("clone", Some(sub_m)) => {}, // clone was used
("push", Some(sub_m)) => {}, // push was used
("commit", Some(sub_m)) => {}, // commit was used
_ => {}, // Either no subcommand or one not tested for...
}
I am displaying a date on the screen using the chrono crate.
The intention is to show the date in the users preferred time or UTC if no is set.
I have the UTC default set up, but I am unsure on the best method to record the user's timezone and how to apply that to the current date.
Note: date might not be set here so I'd prefer to modify date rather than use a different constructor.
let mut date: DateTime<UTC> = UTC::now();
//Convert to the User's Timezone if present
if let Some(user) = user {
//Extract the timezone
date.with_timezone(TimeZone::from_offset(&user.timezone));
}
let date_text = date.format("%H:%M %d/%m/%y").to_string();
What I would like is a type to use for user.timezone and an example on how to set the date.
You can use the chrono-tz crate, which allows you to convert a string to a timezone with chrono_tz::Tz::from_str("Europe/Berlin"). So all your user has to do is to supply a valid timezone string.
You can then use
fn date_time_str<Tz: chrono::TimeZone>(date: DateTime<Tz>, user: User) -> String {
if let Some(user) = user {
if let Ok(tz) = chrono_tz::Tz::from_str(user.timezone) {
let newdate = date.with_timezone(tz);
return newdate.format("%H:%M %d/%m/%y").to_string();
}
}
date.format("%H:%M %d/%m/%y").to_string()
}
You cannot modify the original date variable, because the types won't match. The timezone is part of the type. If you move completely to DateTime<chrono_tz::Tz>, then you could modify the variable, but all your uses of DateTime would need to be changed.