and thanks for looking!
I have an instance of YouTrack with several custom fields, some of which are String-type. I'm implementing a module to create a new issue via the YouTrack REST API's PUT request, and then updating its fields with user-submitted values by applying commands. This works great---most of the time.
I know that I can apply multiple commands to an issue at the same time by concatenating them into the query string, like so:
Type Bug Priority Critical add Fix versions 5.1 tag regression
will result in
Type: Bug
Priority: Critical
Fix versions: 5.1
in their respective fields (as well as adding the regression tag). But, if I try to do the same thing with multiple String-type custom fields, then:
Foo something Example Something else Bar P0001
results in
Foo: something Example Something else Bar P0001
Example:
Bar:
The command only applies to the first field, and the rest of the query string is treated like its String value. I can apply the command individually for each field, but is there an easier way to combine these requests?
Thanks again!
This is an expected result because all string after foo is considered a value of this field, and spaces are also valid symbols for string custom fields.
If you try to apply this command via command window in the UI, you will actually see the same result.
Such a good question.
I encountered the same issue and have spent an unhealthy amount of time in frustration.
Using the command window from the YouTrack UI I noticed it leaves trailing quotations and I was unable to find anything in the documentation which discussed finalizing or identifying the end of a string value. I was also unable to find any mention of setting string field values in the command reference, grammer documentation or examples.
For my solution I am using Python with the requests and urllib modules. - Though I expect you could turn the solution to any language.
The rest API will accept explicit strings in the POST
import requests
import urllib
from collections import OrderedDict
URL = 'http://youtrack.your.address:8000/rest/issue/{issue}/execute?'.format(issue='TEST-1234')
params = OrderedDict({
'State': 'New',
'Priority': 'Critical',
'String Field': '"Message to submit"',
'Other Details': '"Fold the toilet paper to a point when you are finished."'
})
str_cmd = ' '.join(' '.join([k, v]) for k, v in params.items())
command_url = URL + urllib.urlencode({'command':str_cmd})
result = requests.post(command_url)
# The command result:
# http://youtrack.your.address:8000/rest/issue/TEST-1234/execute?command=Priority+Critical+State+New+String+Field+%22Message+to+submit%22+Other+Details+%22Fold+the+toilet+paper+to+a+point+when+you+are+finished.%22
I'm sad to see this one go unanswered for so long. - Hope this helps!
edit:
After continuing my work, I have concluded that sending all the field
updates as a single POST is marginally better for the YouTrack
server, but requires more effort than it's worth to:
1) know all fields in the Issues which are string values
2) pre-process all the string values into string literals
3) If you were to send all your field updates as a single request and just one of them was missing, failed to set, or was an unexpected value, then the entire request will fail and you potentially lose all the other information.
I wish the YouTrack documentation had some mention or discussion of
these considerations.
I'm a total erlang noob and I just want to see what's in a particular table I have. I want to just "select *" from a particular table to start with. The examples I'm seeing, such as the official documentation, all have column restrictions which I don't really want. I don't really know how to form the MatchHead or Guard to match anything (aka "*").
A very simple primer on how to just get everything out of a table would be very appreciated!
For example, you can use qlc:
F = fun() ->
Q = qlc:q([R || R <- mnesia:table(foo)]),
qlc:e(Q)
end,
mnesia:transaction(F).
The simplest way to do it is probably mnesia:dirty_match_object:
mnesia:dirty_match_object(foo, #foo{_ = '_'}).
That is, match everything in the table foo that is a foo record, regardless of the values of the fields (every field is '_', i.e. wildcard). Note that since it uses record construction syntax, it will only work in a module where you have included the record definition, or in the shell after evaluating rr(my_module) to make the record definition available.
(I expected mnesia:dirty_match_object(foo, '_') to work, but that fails with a bad_type error.)
To do it with select, call it like this:
mnesia:dirty_select(foo, [{'_', [], ['$_']}]).
Here, MatchHead is _, i.e. match anything. The guards are [], an empty list, i.e. no extra limitations. The result spec is ['$_'], i.e. return the entire record. For more information about match specs, see the match specifications chapter of the ERTS user guide.
If an expression is too deep and gets printed with ... in the shell, you can ask the shell to print the entire thing by evaluating rp(EXPRESSION). EXPRESSION can either be the function call once again, or v(-1) for the value returned by the previous expression, or v(42) for the value returned by the expression preceded by the shell prompt 42>.
I have this kind of request which seems to be GWT-RPC format :
R7~"61~com.foo.Service~"14~MethodA~D2~"3~F7e~"3~B0e~Ecom.foo.data.BeanType~I116~Lcom.foo.Parameter~I5~"1~b~Z0~"1~n~V~"1~o~Z1~"1~p~Z1~"1~q~V~'
But it is not in line with protocol described here:
https://docs.google.com/document/d/1eG0YocsYYbNAtivkLtcaiEE5IOF5u4LUol8-LL0TIKU/edit
What exactly is this protocol ? Is it really GWT-RPC or something else (deRPC?) ?
Looking into gwt-2.5.1 source code, I notice it seems that following packages could be generating this kind of format:
com.google.gwt.rpc.client
com.google.gwt.rpc.server
Is this deRPC ?
Based on a quick glance through the deRPC classes in the packages you listed, it does indeed appear to be deRPC. Note that deRPC has always been marked as experimental, and is now deprecated, and that either RPC or RequestFactory should be used instead.
Details that seem to confirm this:
com.google.gwt.rpc.client.impl.SimplePayloadSink#RPC_SEPARATOR_CHAR is a constant equal to the ~ character, which appears to be a separator between different tokens in the sample string you provided.
Both com.google.gwt.rpc.client.impl.SimplePayloadSink andcom.google.gwt.rpc.server.SimplePayloadDecoder` have many comments that appear to depict the same basic format that you are seeing in there:
// "4~abcd in endVisit(StringValueCommand x, Context ctx) closely matches several tokens in the sample string - a quote indicating a string, an int describing the length, a ~ separator, then the string itself (this doesnt match everything, I suspect because you removed details about the service and the name of the method):
"3~F7e
"3~B0e
"1~b
Booleans all follow Z1 or Z0, as in your sample string
Especially interesting for me as a PHP/Perl-beginner is this site in Switzerland:
see this link:http://www.edi.admin.ch/esv/00475/00698/index.html?lang=de&webgrab_path=http://esv2000.edi.admin.ch/d/entry.asp?Id=1308
Which has a dataset of 2700 foundations. All the data are free to use with no limitations copyrights on it.
what we have so far: Well the harvesting task should be no problem if i take WWW::Mechanize - particularly for doing the form based search and selecting the individual entries. Hmm - i guess that the algorithm would be basically 2 nested loops: the outer loop runs the form based search, the inner loop processes the search results.
The outer loop would use the select() and the submit_form() functions on the second search form on the page. Can we use DOM processing here. Well - how can we get the get the selection values.
The inner loop through the results would use the follow link function to get to the actual entries using the following call.
$mech->follow_link(url_regex => qr/webgrab_path=http:\/\/evs2000.*\?
Id=\d+$/, n => $result_nbr);
This would forward our mechanic browser to the entry page. Basically the URL query looks for links that have the webgrap_path to Id pattern, which is unique for each database entry. The $result_nbr variable tells mecha which one of the results it should follow next.
If we have several result pages we would also use the same trick to traverse through the result pages. For the semantic extraction of the entry information,we could parse the content of the actual entries with XML:LibXML's html parser (which works fine on this page), because it gives you some powerful DOM selection (using XPath) methods.
Well the actual looping through the pages should be doable in a few lines of perl of max. 20 lines - likely less.
But wait: the processing of the entry pages will then be the most complex part
of the script.
Approaches: In principle we could do the same algorithm with a single while loop
if we use the back() function smartly.
Can you give me a hint for the beginning - the processing of the entry pages - doing this in Perl:: Mechanize
"Which has a dataset of 2700 foundations. All the data are free to use with no limitations copyrights on it."
Not true. See http://perlmonks.org/?node_id=905767
"The data is copyrighted even though it is made available freely: "Downloading or copying of texts, illustrations, photos or any other data does not entail any transfer of rights on the content." (and again, in German, as you've been scraping some other German list to spam before)."
I'm looking for a reasonable way to represent searches as a RESTful URLs.
The setup: I have two models, Cars and Garages, where Cars can be in Garages. So my urls look like:
/car/xxxx
xxx == car id
returns car with given id
/garage/yyy
yyy = garage id
returns garage with given id
A Car can exist on its own (hence the /car), or it can exist in a garage. What's the right way to represent, say, all the cars in a given garage? Something like:
/garage/yyy/cars ?
How about the union of cars in garage yyy and zzz?
What's the right way to represent a search for cars with certain attributes? Say: show me all blue sedans with 4 doors :
/car/search?color=blue&type=sedan&doors=4
or should it be /cars instead?
The use of "search" seems inappropriate there - what's a better way / term? Should it just be:
/cars/?color=blue&type=sedan&doors=4
Should the search parameters be part of the PATHINFO or QUERYSTRING?
In short, I'm looking for guidance for cross-model REST url design, and for search.
[Update] I like Justin's answer, but he doesn't cover the multi-field search case:
/cars/color:blue/type:sedan/doors:4
or something like that. How do we go from
/cars/color/blue
to the multiple field case?
For the searching, use querystrings. This is perfectly RESTful:
/cars?color=blue&type=sedan&doors=4
An advantage to regular querystrings is that they are standard and widely understood and that they can be generated from form-get.
The RESTful pretty URL design is about displaying a resource based on a structure (directory-like structure, date: articles/2005/5/13, object and it's attributes,..), the slash / indicates hierarchical structure, use the -id instead.
Hierarchical structure
I would personaly prefer:
/garage-id/cars/car-id
/cars/car-id #for cars not in garages
If a user removes the /car-id part, it brings the cars preview - intuitive. User exactly knows where in the tree he is, what is he looking at. He knows from the first look, that garages and cars are in relation. /car-id also denotes that it belongs together unlike /car/id.
Searching
The searchquery is OK as it is, there is only your preference, what should be taken into account. The funny part comes when joining searches (see below).
/cars?color=blue;type=sedan #most prefered by me
/cars;color-blue+doors-4+type-sedan #looks good when using car-id
/cars?color=blue&doors=4&type=sedan #also possible, but & blends in with text
Or basically anything what isn't a slash as explained above.
The formula: /cars[?;]color[=-:]blue[,;+&], though I wouldn't use the & sign as it is unrecognizable from the text at first glance if that's your thing.
** Did you know that passing JSON object in URI is RESTful? **
Lists of options
/cars?color=black,blue,red;doors=3,5;type=sedan #most prefered by me
/cars?color:black:blue:red;doors:3:5;type:sedan
/cars?color(black,blue,red);doors(3,5);type(sedan) #does not look bad at all
/cars?color:(black,blue,red);doors:(3,5);type:sedan #little difference
possible features?
Negate search strings (!)
To search any cars, but not black and red:
?color=!black,!red
color:(!black,!red)
Joined searches
Search red or blue or black cars with 3 doors in garages id 1..20 or 101..103 or 999 but not 5
/garage[id=1-20,101-103,999,!5]/cars[color=red,blue,black;doors=3]
You can then construct more complex search queries. (Look at CSS3 attribute matching for the idea of matching substrings. E.g. searching users containing "bar" user*=bar.)
Conclusion
Anyway, this might be the most important part for you, because you can do it however you like after all, just keep in mind that RESTful URI represents a structure which is easily understood e.g. directory-like /directory/file, /collection/node/item, dates /articles/{year}/{month}/{day}.. And when you omit any of last segments, you immediately know what you get.
So.., all these characters are allowed unencoded:
unreserved: a-zA-Z0-9_.-~
Typically allowed both encoded and not, both uses are then equivalent.
special characters: $-_.+!*'(),
reserved: ;/?:#=&
May be used unencoded for the purpose they represent, otherwise they must be encoded.
unsafe: <>"#%{}|^~[]`
Why unsafe and why should rather be encoded: RFC 1738 see 2.2
Also see RFC 1738#page-20 for more character classes.
RFC 3986 see 2.2
Despite of what I previously said, here is a common distinction of delimeters, meaning that some "are" more important than others.
generic delimeters: :/?#[]#
sub-delimeters: !$&'()*+,;=
More reading:
Hierarchy: see 2.3, see 1.2.3
url path parameter syntax
CSS3 attribute matching
IBM: RESTful Web services - The basics
Note: RFC 1738 was updated by RFC 3986
Although having the parameters in the path has some advantages, there are, IMO, some outweighing factors.
Not all characters needed for a search query are permitted in a URL. Most punctuation and Unicode characters would need to be URL encoded as a query string parameter. I'm wrestling with the same problem. I would like to use XPath in the URL, but not all XPath syntax is compatible with a URI path. So for simple paths, /cars/doors/driver/lock/combination would be appropriate to locate the 'combination' element in the driver's door XML document. But /car/doors[id='driver' and lock/combination='1234'] is not so friendly.
There is a difference between filtering a resource based on one of its attributes and specifying a resource.
For example, since
/cars/colors returns a list of all colors for all cars (the resource returned is a collection of color objects)
/cars/colors/red,blue,green would return a list of color objects that are red, blue or green, not a collection of cars.
To return cars, the path would be
/cars?color=red,blue,green or /cars/search?color=red,blue,green
Parameters in the path are more difficult to read because name/value pairs are not isolated from the rest of the path, which is not name/value pairs.
One last comment. I prefer /garages/yyy/cars (always plural) to /garage/yyy/cars (perhaps it was a typo in the original answer) because it avoids changing the path between singular and plural. For words with an added 's', the change is not so bad, but changing /person/yyy/friends to /people/yyy seems cumbersome.
To expand on Peter's answer - you could make Search a first-class resource:
POST /searches # create a new search
GET /searches # list all searches (admin)
GET /searches/{id} # show the results of a previously-run search
DELETE /searches/{id} # delete a search (admin)
The Search resource would have fields for color, make model, garaged status, etc and could be specified in XML, JSON, or any other format. Like the Car and Garage resource, you could restrict access to Searches based on authentication. Users who frequently run the same Searches can store them in their profiles so that they don't need to be re-created. The URLs will be short enough that in many cases they can be easily traded via email. These stored Searches can be the basis of custom RSS feeds, and so on.
There are many possibilities for using Searches when you think of them as resources.
The idea is explained in more detail in this Railscast.
Justin's answer is probably the way to go, although in some applications it might make sense to consider a particular search as a resource in its own right, such as if you want to support named saved searches:
/search/{searchQuery}
or
/search/{savedSearchName}
I use two approaches to implement searches.
1) Simplest case, to query associated elements, and for navigation.
/cars?q.garage.id.eq=1
This means, query cars that have garage ID equal to 1.
It is also possible to create more complex searches:
/cars?q.garage.street.eq=FirstStreet&q.color.ne=red&offset=300&max=100
Cars in all garages in FirstStreet that are not red (3rd page, 100 elements per page).
2) Complex queries are considered as regular resources that are created and can be recovered.
POST /searches => Create
GET /searches/1 => Recover search
GET /searches/1?offset=300&max=100 => pagination in search
The POST body for search creation is as follows:
{
"$class":"test.Car",
"$q":{
"$eq" : { "color" : "red" },
"garage" : {
"$ne" : { "street" : "FirstStreet" }
}
}
}
It is based in Grails (criteria DSL): http://grails.org/doc/2.4.3/ref/Domain%20Classes/createCriteria.html
This is not REST. You cannot define URIs for resources inside your API. Resource navigation must be hypertext-driven. It's fine if you want pretty URIs and heavy amounts of coupling, but just do not call it REST, because it directly violates the constraints of RESTful architecture.
See this article by the inventor of REST.
In addition i would also suggest:
/cars/search/all{?color,model,year}
/cars/search/by-parameters{?color,model,year}
/cars/search/by-vendor{?vendor}
Here, Search is considered as a child resource of Cars resource.
There are a lot of good options for your case here. Still you should considering using the POST body.
The query string is perfect for your example, but if you have something more complicated, e.g. an arbitrary long list of items or boolean conditionals, you might want to define the post as a document, that the client sends over POST.
This allows a more flexible description of the search, as well as avoids the Server URL length limit.
RESTful does not recommend using verbs in URL's /cars/search is not restful. The right way to filter/search/paginate your API's is through Query Parameters. However there might be cases when you have to break the norm. For example, if you are searching across multiple resources, then you have to use something like /search?q=query
You can go through http://saipraveenblog.wordpress.com/2014/09/29/rest-api-best-practices/ to understand the best practices for designing RESTful API's
Though I like Justin's response, I feel it more accurately represents a filter rather than a search. What if I want to know about cars with names that start with cam?
The way I see it, you could build it into the way you handle specific resources:
/cars/cam*
Or, you could simply add it into the filter:
/cars/doors/4/name/cam*/colors/red,blue,green
Personally, I prefer the latter, however I am by no means an expert on REST (having first heard of it only 2 or so weeks ago...)
My advice would be this:
/garages
Returns list of garages (think JSON array here)
/garages/yyy
Returns specific garage
/garage/yyy/cars
Returns list of cars in garage
/garages/cars
Returns list of all cars in all garages (may not be practical of course)
/cars
Returns list of all cars
/cars/xxx
Returns specific car
/cars/colors
Returns lists of all posible colors for cars
/cars/colors/red,blue,green
Returns list of cars of the specific colors (yes commas are allowed :) )
Edit:
/cars/colors/red,blue,green/doors/2
Returns list of all red,blue, and green cars with 2 doors.
/cars/type/hatchback,coupe/colors/red,blue,green/
Same idea as the above but a lil more intuitive.
/cars/colors/red,blue,green/doors/two-door,four-door
All cars that are red, blue, green and have either two or four doors.
Hopefully that gives you the idea. Essentially your Rest API should be easily discoverable and should enable you to browse through your data. Another advantage with using URLs and not query strings is that you are able to take advantage of the native caching mechanisms that exist on the web server for HTTP traffic.
Here's a link to a page describing the evils of query strings in REST: http://web.archive.org/web/20070815111413/http://rest.blueoxen.net/cgi-bin/wiki.pl?QueryStringsConsideredHarmful
I used Google's cache because the normal page wasn't working for me here's that link as well:
http://rest.blueoxen.net/cgi-bin/wiki.pl?QueryStringsConsideredHarmful