.\" Automatically generated by Pod::Man 4.14 (Pod::Simple 3.43) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. Capital omega is used to do unbreakable dashes and .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff, .\" nothing in troff, for use with C<>. .tr \(*W- .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' .ie n \{\ . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} .el\{\ . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" ======================================================================== .\" .IX Title "Catalyst::View::JSON 3pm" .TH Catalyst::View::JSON 3pm "2022-12-06" "perl v5.36.0" "User Contributed Perl Documentation" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" Catalyst::View::JSON \- JSON view for your data .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 4 \& # lib/MyApp/View/JSON.pm \& package MyApp::View::JSON; \& use base qw( Catalyst::View::JSON ); \& 1; \& \& # configure in lib/MyApp.pm \& MyApp\->config({ \& ... \& \*(AqView::JSON\*(Aq => { \& allow_callback => 1, # defaults to 0 \& callback_param => \*(Aqcb\*(Aq, # defaults to \*(Aqcallback\*(Aq \& expose_stash => [ qw(foo bar) ], # defaults to everything \& }, \& }); \& \& sub hello : Local { \& my($self, $c) = @_; \& $c\->stash\->{message} = \*(AqHello World!\*(Aq; \& $c\->forward(\*(AqView::JSON\*(Aq); \& } .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" Catalyst::View::JSON is a Catalyst View handler that returns stash data in \s-1JSON\s0 format. .SH "CONFIG VARIABLES" .IX Header "CONFIG VARIABLES" .IP "allow_callback" 4 .IX Item "allow_callback" Flag to allow callbacks by adding \f(CW\*(C`callback=function\*(C'\fR. Defaults to 0 (doesn't allow callbacks). See \*(L"\s-1CALLBACKS\*(R"\s0 for details. .IP "callback_param" 4 .IX Item "callback_param" Name of \s-1URI\s0 parameter to specify \s-1JSON\s0 callback function name. Defaults to \f(CW\*(C`callback\*(C'\fR. Only effective when \f(CW\*(C`allow_callback\*(C'\fR is turned on. .IP "expose_stash" 4 .IX Item "expose_stash" Scalar, List or regular expression object, to specify which stash keys are exposed as a \s-1JSON\s0 response. Defaults to everything. Examples configuration: .Sp .Vb 2 \& # use \*(Aqjson_data\*(Aq value as a data to return \& expose_stash => \*(Aqjson_data\*(Aq, \& \& # only exposes keys \*(Aqfoo\*(Aq and \*(Aqbar\*(Aq \& expose_stash => [ qw( foo bar ) ], \& \& # only exposes keys that matches with /^json_/ \& expose_stash => qr/^json_/, .Ve .Sp Suppose you have data structure of the following. .Sp .Vb 2 \& $c\->stash\->{foo} = [ 1, 2 ]; \& $c\->stash\->{bar} = 2; .Ve .Sp By default, this view will return: .Sp .Vb 1 \& {"foo":[1,2],"bar":2} .Ve .Sp When you set \f(CW\*(C`expose_stash => [ \*(Aqfoo\*(Aq ]\*(C'\fR, it'll return .Sp .Vb 1 \& {"foo":[1,2]} .Ve .Sp and in the case of \f(CW\*(C`expose_stash => \*(Aqfoo\*(Aq\*(C'\fR, it'll just return .Sp .Vb 1 \& [1,2] .Ve .Sp instead of the whole object (hashref in perl). This option will be useful when you share the method with different views (e.g. \s-1TT\s0) and don't want to expose non-irrelevant stash variables as in \s-1JSON.\s0 .IP "no_x_json_header" 4 .IX Item "no_x_json_header" .Vb 1 \& no_x_json_header: 1 .Ve .Sp By default this plugin sets X\-JSON header if the requested client is a Prototype.js with X\-JSON support. By setting 1, you can opt-out this behavior so that you can do \fBeval()\fR by your own. Defaults to 0. .IP "json_encoder_args" 4 .IX Item "json_encoder_args" An optional hashref that supplies arguments to JSON::MaybeXS used when creating a new object. .IP "use_force_bom" 4 .IX Item "use_force_bom" If versions of this view older than 0.36, there was some code that added a \s-1UTF\-8 BOM\s0 marker to the end of the \s-1JSON\s0 string when the user agent was Safari. After looking at a lot of existing code I don't think this is needed anymore so we removed it by default. However if this turns out to be a problem you can re enable it by setting this attribute to true. Possible a breaking change so we offer this workaround. .Sp You may also override the method 'user_agent_bom_test' which received the current request user agent string to try and better determine if this is needed. Patches for this welcomed. .SH "METHODS" .IX Header "METHODS" .SS "process" .IX Subsection "process" Standard target of \f(CW$c\fR\->forward used to prepare a response .SS "render" .IX Subsection "render" The methods accepts either of the following argument signatures in order to promote compatibility with the semi standard render method as define in numerous Catalyst views on \s-1CPAN:\s0 .PP .Vb 2 \& my $json_string = $c\->view(\*(AqJSON\*(Aq)\->render($c, undef, $data); \& my $json_string = $c\->view(\*(AqJSON\*(Aq)\->render($c, $data); .Ve .PP Given '$data' returns the \s-1JSON\s0 serialized version, or throws and error. .SH "OVERRIDING JSON ENCODER" .IX Header "OVERRIDING JSON ENCODER" By default it uses JSON::MaybeXS::encode_json to serialize perl data structure into \&\s-1JSON\s0 data format. If you want to avoid this and encode with your own encoder (like passing different options to JSON::MaybeXS etc.), you can implement the \f(CW\*(C`encode_json\*(C'\fR method in your View class. .PP .Vb 2 \& package MyApp::View::JSON; \& use base qw( Catalyst::View::JSON ); \& \& use JSON::MaybeXS (); \& \& sub encode_json { \& my($self, $c, $data) = @_; \& my $encoder = JSON::MaybeXS\->new\->(ascii => 1, pretty => 1, allow_nonref => 1); \& $encoder\->encode($data); \& } \& \& 1; .Ve .SH "ENCODINGS" .IX Header "ENCODINGS" \&\fB\s-1NOTE\s0\fR Starting in release v5.90080 Catalyst encodes all text like body returns as \s-1UTF8.\s0 It however ignores content types like application/json and assumes that a correct \s-1JSON\s0 serializer is doing what it is supposed to do, which is encode \s-1UTF8\s0 automatically. In general this is what this view does so you shoulding need to mess with the encoding flag here unless you have some odd case. .PP Also, the comment about regard 'browser gotcha's' was written a number of years ago and I can't say one way or another if those gotchas continue to be common in the wild. .PP \&\fB\s-1NOTE\s0\fR Setting this configuration has no bearing on how the actual serialized string is encoded. This \s-1ONLY\s0 sets the content type header in your response. By default we set the 'utf8' flag on JSON::MaybeXS so that the string generated and set to your response body is proper \s-1UTF8\s0 octets that can be transmitted over \s-1HTTP.\s0 If you are planning to do some alternative encoding you should turn off this default via the \f(CW\*(C`json_encoder_args\*(C'\fR: .PP .Vb 2 \& MyApp::View::JSON\->config( \& json_encoder_args => +{utf8=>0} ); .Ve .PP \&\fB\s-1NOTE\s0\fR In 2015 the use of \s-1UTF8\s0 as encoding is widely standard so it is very likely you should need to do nothing to get the correct encoding. The following documentation will remain for historical value and backcompat needs. .PP Due to the browser gotchas like those of Safari and Opera, sometimes you have to specify a valid charset value in the response's Content-Type header, e.g. \f(CW\*(C`text/javascript; charset=utf\-8\*(C'\fR. .PP Catalyst::View::JSON comes with the configuration variable \f(CW\*(C`encoding\*(C'\fR which defaults to utf\-8. You can change it via \f(CW\*(C`YourApp\->config\*(C'\fR or even runtime, using \f(CW\*(C`component\*(C'\fR. .PP .Vb 1 \& $c\->component(\*(AqView::JSON\*(Aq)\->encoding(\*(Aqeuc\-jp\*(Aq); .Ve .PP This assumes you set your stash data in raw euc-jp bytes, or Unicode flagged variable. In case of Unicode flagged variable, Catalyst::View::JSON automatically encodes the data into your \&\f(CW\*(C`encoding\*(C'\fR value (euc-jp in this case) before emitting the data to the browser. .PP Another option would be to use \fIJavaScript-UCS\fR as an encoding (and pass Unicode flagged string to the stash). That way all non-ASCII characters in the output \s-1JSON\s0 will be automatically encoded to JavaScript Unicode encoding like \fI\euXXXX\fR. You have to install Encode::JavaScript::UCS to use the encoding. .SH "CALLBACKS" .IX Header "CALLBACKS" By default it returns raw \s-1JSON\s0 data so your JavaScript app can deal with using XMLHttpRequest calls. Adding callbacks (\s-1JSONP\s0) to the \s-1API\s0 gives more flexibility to the end users of the \s-1API:\s0 overcome the cross-domain restrictions of XMLHttpRequest. It can be done by appending \fIscript\fR node with dynamic \s-1DOM\s0 manipulation, and associate callback handler to the returned data. .PP For example, suppose you have the following code. .PP .Vb 8 \& sub end : Private { \& my($self, $c) = @_; \& if ($c\->req\->param(\*(Aqoutput\*(Aq) eq \*(Aqjson\*(Aq) { \& $c\->forward(\*(AqView::JSON\*(Aq); \& } else { \& ... \& } \& } .Ve .PP \&\f(CW\*(C`/foo/bar?output=json\*(C'\fR will just return the data set in \&\f(CW\*(C`$c\->stash\*(C'\fR as \s-1JSON\s0 format, like: .PP .Vb 1 \& { result: "foo", message: "Hello" } .Ve .PP but \f(CW\*(C`/foo/bar?output=json&callback=handle_result\*(C'\fR will give you: .PP .Vb 1 \& handle_result({ result: "foo", message: "Hello" }); .Ve .PP and you can write a custom \f(CW\*(C`handle_result\*(C'\fR function to handle the returned data asynchronously. .PP The valid characters you can use in the callback function are .PP .Vb 1 \& [a\-zA\-Z0\-9\e.\e_\e[\e]] .Ve .PP but you can customize the behaviour by overriding the \&\f(CW\*(C`validate_callback_param\*(C'\fR method in your View::JSON class. .PP See and for more about \&\s-1JSONP.\s0 .PP \&\fB\s-1NOTE\s0\fR For another way to enable \s-1JSONP\s0 in your application take a look at Plack::Middleware::JSONP .SH "INTEROPERABILITY" .IX Header "INTEROPERABILITY" \&\s-1JSON\s0 use is still developing and has not been standardized. This section provides some notes on various libraries. .PP Dojo Toolkit: Setting dojo.io.bind's mimetype to 'text/json' in the JavaScript request will instruct dojo.io.bind to expect \s-1JSON\s0 data in the response body and auto-eval it. Dojo ignores the server response Content-Type. This works transparently with Catalyst::View::JSON. .PP Prototype.js: prototype.js will auto-eval \s-1JSON\s0 data that is returned in the custom X\-JSON header. The reason given for this is to allow a separate \s-1HTML\s0 fragment in the response body, however this of limited use because \s-1IE 6\s0 has a max header length that will cause the \s-1JSON\s0 evaluation to silently fail when reached. The recommend approach is to use Catalyst::View::JSON which will \s-1JSON\s0 format all the response data and return it in the response body. .PP In at least prototype 1.5.0 rc0 and above, prototype.js will send the X\-Prototype-Version header. If this is encountered, a JavaScript eval will be returned in the X\-JSON response header to automatically eval the response body, unless you set \fIno_x_json_header\fR to 1. If your version of prototype does not send this header, you can manually eval the response body using the following JavaScript: .PP .Vb 7 \& evalJSON: function(request) { \& try { \& return eval(\*(Aq(\*(Aq + request.responseText + \*(Aq)\*(Aq); \& } catch (e) {} \& } \& // elsewhere \& var json = this.evalJSON(request); .Ve .PP \&\fB\s-1NOTE\s0\fR The above comments were written a number of years ago and I would take then with a grain of salt so to speak. For now I will leave them in place but not sure they are meaningful in 2015. .SH "SECURITY CONSIDERATION" .IX Header "SECURITY CONSIDERATION" Catalyst::View::JSON makes the data available as a (sort of) JavaScript to the client, so you might want to be careful about the security of your data. .SS "Use callbacks only for public data" .IX Subsection "Use callbacks only for public data" When you enable callbacks (\s-1JSONP\s0) by setting \f(CW\*(C`allow_callback\*(C'\fR, all your \s-1JSON\s0 data will be available cross-site. This means embedding private data of logged-in user to \s-1JSON\s0 is considered bad. .PP .Vb 3 \& # MyApp.yaml \& View::JSON: \& allow_callback: 1 \& \& sub foo : Local { \& my($self, $c) = @_; \& $c\->stash\->{address} = $c\->user\->street_address; # BAD \& $c\->forward(\*(AqView::JSON\*(Aq); \& } .Ve .PP If you want to enable callbacks in a controller (for public \s-1API\s0) and disable in another, you need to create two different View classes, like MyApp::View::JSON and MyApp::View::JSONP, because \&\f(CW\*(C`allow_callback\*(C'\fR is a static configuration of the View::JSON class. .PP See for more. .SS "Avoid valid cross-site \s-1JSON\s0 requests" .IX Subsection "Avoid valid cross-site JSON requests" Even if you disable the callbacks, the nature of JavaScript still has a possibility to access private \s-1JSON\s0 data cross-site, by overriding Array constructor \f(CW\*(C`[]\*(C'\fR. .PP .Vb 3 \& # MyApp.yaml \& View::JSON: \& expose_stash: json \& \& sub foo : Local { \& my($self, $c) = @_; \& $c\->stash\->{json} = [ $c\->user\->street_address ]; # BAD \& $c\->forward(\*(AqView::JSON\*(Aq); \& } .Ve .PP When you return logged-in user's private data to the response \s-1JSON,\s0 you might want to disable \s-1GET\s0 requests (because \fIscript\fR tag invokes \&\s-1GET\s0 requests), or include a random digest string and validate it. .PP See for more. .SH "AUTHOR" .IX Header "AUTHOR" Tatsuhiko Miyagawa .SH "LICENSE" .IX Header "LICENSE" This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. .SH "CONTRIBUTORS" .IX Header "CONTRIBUTORS" Following people has been contributing patches, bug reports and suggestions for the improvement of Catalyst::View::JSON. .PP .Vb 5 \& John Wang \& kazeburo \& Daisuke Murase \& Jun Kuriyama \& Tomas Doran .Ve .SH "SEE ALSO" .IX Header "SEE ALSO" Catalyst, JSON::MaybeXS, Encode::JavaScript::UCS .PP