I'm trying to send multiple values to a file / socket / some kind of writer. Each of those writes results in IoResult. How can I handle a whole batch of values nicely in that case? Result provides .and_then(...), but that makes the code look really ugly. Is there a better way than this?
return
writer.write(thing1).and_then(|()| {
writer.write(thing2).and_then(|()| {
...
writer.write(thing10)
})})})})})})})})})
A try! macro will help you here:
try!(writer.write(thing1))
try!(writer.write(thing2))
...
try!(writer.write(thing10))
It's defined like this:
macro_rules! try(
($e:expr) => (match $e { Ok(e) => e, Err(e) => return Err(e) })
)
Related
I am new to elasticsearch so I will need some help. Unfortunately, I didnt found the answer in other topics here on SO.
I have some .net core application which I inherited and now there is a need to implement some changes.
I already have a method of getting data from elasticsearch, but after getting them, I am not sure how to change it and use it in application.
To be precise, I need to parse first and last name and to remove special characters, specific serbian latin letters like "šđžčć" etc... I already have a method for this parsing written but not sure how to call it...
So, my question is can I and how can I do this?
What I have now is the following:
var result = await _elasticClient.SearchAsync<CachedUserEntity>(
s =>
s.Index(_aliasName)
.Query(q => andQuery));
CachedUserEntity, among others, contains property about FirstName and LastName.
Inside results.Documents, I am getting the data about FirstName and LastName from elasticsearch, but I am not sure how to access it in order to update it via aformentioned NameParser ...
Sorry if the question is too easy, not to say stupid :)
I wont use updateByQuery here, for some reasons. I would scroll on documents (i use matchAll on my exemple, you obviously need to replace it with your query), or, if you dont know how to identify documents to update, only update usefull documents in UpdateManyWithIndex/UpdateManyPartial function.
For performance, we have to update severals documents at once, so we use bulk/updateMany function.
You can use both solution, the classic update, or the second (partial update) with an object containing the targeteds fields.
On server sides, both solutions will have the same cost / performance.
var searchResponse = Client.Search<CachedUserEntity>(s => s
.Query(q => q
MatchAll()
)
.Scroll("10s")
);
while (searchResponse.Documents.Any())
{
List<CachedUserEntity> NewSearchResponse = RemoveChar(searchResponse);
UpdateManyWithIndex<CachedUserEntity>(NewSearchResponse, _aliasName);
searchResponse = Client.Scroll<Project>("2h", searchResponse.ScrollId);
}
public void UpdateManyWithIndex<C>(List<C> obj, string index) where C : class {
var bulkResponse = Client.Bulk(b => b
.Index(index).Refresh(Elasticsearch.Net.Refresh.WaitFor) // explicitly provide index name
.UpdateMany<C>(obj, (bu, d) => bu.Doc(d)));
}
Or, using partial update object
Note: in this case Indix is already set on my client (add .index if needed)
var searchResponse = Client.Search<CachedUserEntity>(s => s
.Query(q => q
MatchAll()
)
.Scroll("2h")
);
while (searchResponse.Documents.Any())
{
List<object> listPocoPartialObj = GetPocoPartialObjList(searchResponse);
UpdateManyPartial(listPocoPartialObj);
searchResponse = Client.Scroll<Project>("2h", searchResponse.ScrollId);
}
private List<object> GetPocoPartialObjList(List<CachedUserEntity> cachedList) {
List<object> listPoco = new List<object>();
//note if you dont have cachedList.Id, take a look at result.source, comments if needed
foreach (var eltCached in cachedList) {
listPoco.Add( new object() { Id = cachedList.Id, FirstName = YOURFIELDWITHOUTSPECIALCHAR, LastName = YOURSECONDFIELDWITHOUTSPECIALCHAR});
}
return listPoco;
}
public bool UpdateManyPartial(List<object> partialObj)
{
var bulkResponse = Client.Bulk(b => b
.Refresh(Elasticsearch.Net.Refresh.WaitFor)
.UpdateMany(partialObj, (bu, d) => bu.Doc(d))
);
if (!bulkResponse.IsValid)
{
GetErrorMsgs(bulkResponse);
}
return (bulkResponse?.IsValid == true);
}
I have this API setup in Express but I cannot figure out how to correctly prepare the language filter with the IN statement using SQLite3 in node.js.
The first query applies the language filter correctly. I get the correct results but this could pose a sql injection risk.
The second query finds no results because of the language filter.
How do I correctly setup the db.prepare statement to accept both words, and language?
app.post('/api/languages/:language/getTextWords', (req, res) => {
let words = req.body.map(word => word.toLowerCase())
let wordMap = words.map(() => "?").join(',')
let language = req.params.language.toLowerCase();
// the language filter is applied correctly I get results but the statement is not fully prepared
// let query = db.prepare(`SELECT * FROM words WHERE word IN (${wordMap}) AND language = '${language}'`, words)
// no results are found because of the language filter
let query = db.prepare(`SELECT * FROM words WHERE word IN (${wordMap}) AND language = '?'`, words, language)
query.all((err, rows) => {
if (err) {
res.status(500).send(err.message)
throw err;
}
if (!rows) {
res.json([])
}
if (rows) {
res.json(rows)
}
})
})
Here is a screenshot of the DB table in question:
words table
pass values as an array:
let query = db.prepare(`SELECT * FROM words WHERE word IN (${wordMap}) AND language = ?`, [...words, language]);
In akka-http, how do we extract a list of query parameters of varying length from incoming request?
Request url can be like this:
.../employees?city=london,ny,paris
Number of cities may vary with every request.
From your solution, you can replace the Symbol part like
parameters("city".repeated)
See the akka doc
If you want to keep your value as a comma-separated list of values, you can create a custom directive like
def paramAsList(key: String): Directive1[List[String]] =
parameter(key)
.map(x => x.split(",").toList)
...
get {
paramAsList("city") => cities {
....
With this, your url .../employees?city=london,ny,paris should work
Got it working as:
path("searchByCity") {
get {
parameters(Symbol("city").*) {cities =>
.....
}
}
}
URL is now as:
.../employees?city=london&city=ny&city=paris
function getQueryParams(url){
let urlParts = url.split('?');
if(urlsParts?.length > 1){
let params = urlParts[1].split('&');
return params
}
return null
}
var queryParams = getQueryParams('.../employees?city=london,ny,paris')
Is there a sensible way to have one perl6 module check for the presence of another perl6 module and to 'use' it if and only if it is installed?
Something like this...
module Polygons;
if $available {
use Measure; #only if Measure is installed
}
class Rectangle is export {
has $.width;
has $.height;
method area {
$!width * $!height; #provides operator overload for Measure * Measure
}
}
#====================
module Measure;
class Measure is export {
has $.value;
has $.unit;
method Real {
$!value;
}
method Str {
"$!value $!unit";
}
method multiply( $argument ) {
my $result = $.;
$result.value = $!value * $argument;
$result.unit = "$!unit2";
return $result;
}
}
multi infix:<*> ( Measure:D $left, Measure:D $right ) is export {
return $result.multiply( $argument );
}
#====================
#main.p6
use Polygons;
use Measure;
my $x = Measure.new( value => 10, unit => 'm' );
my $y = Measure.new( value => 20, unit => 'm' );
my $rect = Rectangle.new( width => $x, height => y );
say $rect.area; #'200 m2'
The idea is to propagate the operator overload (infix:<*> in this case) back up the class inheritance so that one store more elaborate objects in the attributes.
(Without tearing up the drains please - since I suspect there is always a way!)
So the first version of this answer was essentially useless.
Here's the first new thing I've come up with that works with what I understand your problem to be. I haven't tried it on the repo yet.
In a file a-module.pm6:
unit module a-module;
our sub infix:<*> ($l,$r) { $l + $r } }
The our means we'll be able to see this routine if we can require it, though it'll only be visible via its fully qualified name &a-module::infix:<*>.
Then in a using file:
use lib '.';
try require a-module;
my &infix:<*> = &a-module::infix:<*> // &OUTER::infix:<*>;
say 1 * 2 # 2 or 3 depending on whether `a-module.pm6` is found
The default routine used if the module is missing can be the one from OUTER (as shown) or from CALLER or whatever other pseudo package you prefer.
This problem/solution seems so basic I suspect it must be on SO or in the doc somewhere. I'll publish what I've got then explore more tomorrow.
While exploring the documented example raised in this perl6 question that was asked here recently, I found that the final implementation option - (my interpretation of the example is that it provides three different ways to do something) - doesn't work. Running this;
class HTTP::Header does Associative {
has %!fields handles <iterator list kv keys values>;
sub normalize-key ($key) { $key.subst(/\w+/, *.tc, :g) }
method EXISTS-KEY ($key) { %!fields{normalize-key $key}:exists }
method DELETE-KEY ($key) { %!fields{normalize-key $key}:delete }
method push (*#_) { %!fields.push: #_ }
multi method AT-KEY (::?CLASS:D: $key) is rw {
my $element := %!fields{normalize-key $key};
Proxy.new(
FETCH => method () { $element },
STORE => method ($value) {
$element = do given $value».split(/',' \s+/).flat {
when 1 { .[0] } # a single value is stored as a string
default { .Array } # multiple values are stored as an array
}
}
);
}
}
my $header = HTTP::Header.new;
say $header.WHAT; #-> (Header)
$header<Accept> = "text/plain";
$header{'Accept-' X~ <Charset Encoding Language>} = <utf-8 gzip en>;
$header.push('Accept-Language' => "fr"); # like .push on a Hash
say $header<Accept-Language>.perl; #-> $["en", "fr"]
... produces the expected output. Note that the third last line with the X meta-operator assigns a literal list (built with angle brackets) to a hash slice (given a flexible definition of "hash"). My understanding is this results in three seperate calls to method AT-KEY each with a single string argument (apart from self) and therefore does not exersise the default clause of the given statement. Is that correct?
When I invent a use case that excersises that part of the code, it appears to fail;
... as above ...
$header<Accept> = "text/plain";
$header{'Accept-' X~ <Charset Encoding Language>} = <utf-8 gzip en>;
$header{'Accept-Language'} = "en, fr, cz";
say $header<Accept-Language>.perl; #-> ["en", "fr", "cz"] ??
# outputs
(Header)
This Seq has already been iterated, and its values consumed
(you might solve this by adding .cache on usages of the Seq, or
by assigning the Seq into an array)
in block at ./hhorig.pl line 20
in method <anon> at ./hhorig.pl line 18
in block <unit> at ./hhorig.pl line 32
The error message provides an awesome explanation - the topic is a sequence produced by the split and is now spent and hence can't be referenced in the when and/or default clauses.
Have I correctly "lifted" and implemented the example? Is my invented use case of several language codes in the one string wrong or is the example code wrong/out-of-date? I say out-of-date as my recollection is that Seq's came along pretty late in the perl6 development process - so perhaps, this code used to work but doesn't now. Can anyone clarify/confirm?
Finally, taking the error message into account, the following code appears to solve the problem;
... as above ...
STORE => method ($value) {
my #values = $value».split(/',' \s+/) ;
$element = do given #values.flat {
when 1 { $value } # a single value is stored as a string
default { #values } # multiple values are stored as an array
}
}
... but is it an exact equivalent?
That code works now (Rakudo 2018.04) and prints
$["en", "fr", "cz"]
as intended. It was probably a bug which was eventually solved.