I am trying to serialize some Clojure data structure into a persistent database, and I currently use Chesire for that purpose.
Let's say I have a map that contains namespaced keywords like the following :
{:cemerick.friend/identity {:current friend, :authentications {friend {:identity friend, :roles #{:clojure-cms.handler/user}}}}}
It gets serialized into JSON, like that :
{"cemerick.friend/identity":{"current":"friend","authentications":{"friend":{"identity":"friend","roles":["clojure-cms.handler/user"]}}}}
When reading it back and serializing (with keywordization (parse-string data true)), I get back the following :
{:cemerick.friend/identity {:current friend, :authentications {:friend {:identity friend, :roles [clojure-cms.handler/user]}}}}
How can I parse this JSON with and get the same data as the original ?
Note : this question gives some context to what I am trying to achieve.
Looking at the tests in Chesire, it's quite obvious that the optional keyword parameter to parse-string will affect all name attributes in a JSON object, value attributes like the namespaced keyword in your example are not affected. Actually, your problem is two-fold: the original set is also not converted back correctly.
For the set problem, what you could do is to write a custom decoder as described in the Chesire documentation.
For the original problem, there is probably no direct way other than to post-process the returned map, find the value to :roles and turn the value into a keyword, like so (untested):
(defn postprocess-json [authmap]
(update-in authmap [:authentications :friend :roles] keyword))
Related
Using the Play framework with Anorm, I would like to write a Controller method that simply returns the results of an SQL query as JSON. I don't want to bother converting to objects. Also, ideally this code should stream out the JSON as the SQL ResultSet is processed rather than processing the entire SQL result before returning anything to the client.
select colA colB from mytable
JSON Response
[{"colA": "ValueA", "colB": 33}, {"colA": "ValueA2", "colB": 34}, ...]
I would like to express this in Scala code as elegantly and concisely as possible, but the examples I'm finding seem to have a lot of boiler plate (redundant column name definitions). I'm surprised there isn't some kind of SqlResult to JsValue conversion in Play or Anorm already.
I realize you may need to define Writes[] or an Enumeratee implementation to achieve this, but once the conversion code is defined, I'd like the code for each method to be nearly as simple as this:
val columns = List("colA", "colB")
db.withConnection { implicit c =>
Ok(Json.toJson(SQL"select #$columns from mytable"))
}
I'm not clear on the best way to define column names just once and pass it to the SQL query as well as JSON conversion code. Maybe if I create some kind of implicit ColumnNames type, the JSON conversion code could access it in the previous example?
Or maybe define my own kind of SqlToJsonAction to achieve even simpler code and have common control over JSON responses?
def getJson = SqlToJsonAction(List("colA", "colB")) { columns =>
SQL"select #$columns from mytable"
}
The only related StackOverflow question I found was: Convert from MySQL query result or LIST to JSON, which didn't have helpful answers.
I'm a Java developer just learning Scala so I still have a lot to learn about the language, but I've read through the Anorm, Iteratee/Enumeratee, Writes, docs and numerous blogs on Anorm, and am having trouble figuring out how to setup the necessary helper code so that I can compose my JSON methods this way.
Also, I'm unclear on what approaches allow Streaming out the Response, and which will iterate the entire SQL ResultSet before responding with anything to the client. According to Anorm Streaming Results only methods such as fold/foldWhile/withResult and Iteratees stream. Are these the techniques I should use?
Bonus:
In some cases, I'll probably want to map a SQL column name to a different JSON field name. Is there a slick way to do this as well?
Something like this (no idea if this Scala syntax is possible):
def getJson = SqlToJsonAction("colA" -> "jsonColA", "colB", "colC" -> "jsonColC")) { columns =>
SQL"select #$columns from mytable"
}
I got an anonymous array which I want to deserialize, here the example of the first array object
[
{ "time":"08:55:54",
"date":"2016-05-27",
"timestamp":1464332154807,
"level":3,
"message":"registerResourcePath ('', '/sap/bc/ui5_ui5/ui2/ushell/resources/')",
"details":"","component":"sap.ui.ModuleSystem"},
{"time":"08:55:54","date":"2016-05-27","timestamp":1464332154808,"level":3,"message":"URL prefixes set to:","details":"","component":"sap.ui.ModuleSystem"},
{"time":"08:55:54","date":"2016-05-27","timestamp":1464332154808,"level":3,"message":" (default) : /sap/bc/ui5_ui5/ui2/ushell/resources/","details":"","component":"sap.ui.ModuleSystem"}
]
I tried deserializing using CL_TREX_JSON_SERIALIZER, but it is corrupt and does not work with my JSON, here is why
Then I tried /UI2/CL_JSON, but it needs a "structure" that perfectly fits the object given by the JSON Object. "Structure" means in my case an internal table of objects with the attributes time, date, timestamp, level, messageanddetails. And there was the problem: it does not properly handle references and uses class description to describe the field assigned to the field-symbol. Since I can not have a list of objects but only a list of references to objects that solution also doesn't works.
As a third attempt I tried with the CALL TRANSFORMATION as described by Horst Keller, but with this method I was not able to read in an anonymous array, and here is why
My major points:
I do not want to change the JSON, since that is what I get from sap.ui.log
I prefere to use built-in functionality and not a thirdparty framework
Your problem comes out not from the anonymity of array, but from the awkwardness of SAP JSON (De)serializer, which doesn't respect double quotes, which enclose JSON attributes. The issue is thoroughly described in this answer.
If you don't want to change your JSON on-the-fly, the only way you have is to change CL_TREX_JSON_DESERIALIZER class like this.
/UI5/CL_JSON_PARSER parses JSONs with unknown format.
Note that it's got "for internal use" written on it so many times that you probably should take it seriously and clone its code to fixate it.
I'm trying to pass a value via JSON that I am having trouble accessing. We have a data structure (that was obviously not built by me otherwise I would likely understand it) that looks something like this when sent to the browser:
{Foo(Bar(List(Baz(List(G3),w))),G3,None)}
This is sent via a JSON write method, but the originating Scala line looks like:
val hint = Some(s"{$question}") where $question is of type Foo.
I've tried using dot notation to access the list items in ways that I thought would work:
val hint = Some(s"{$question.Bar.Baz})"
val hint = Some(s"{$question.Bar(0).Baz(0)"})
It's the deepest G3 I wanted to strip out and send, but instead the JSON object comes through looking like:
{Foo(Bar(List(Baz(List(G3),w))),G3,None)}.Bar.Baz or
{Foo(Bar(List(Baz(List(G3),w))),G3,None)}.Bar(0).Baz(0)
I must be fundamentally missing something about the data structures involved here.
I think you're just using the wrong syntax. The $ needs to come before the {} and the {} is necessary for any expression more complicated than just a variable name:
s"${question.bar(0).baz(0)}"
Is this possible to have a node property as json raw string and to filter on it with cypher ?
I have a node with some defined properties and metadata (json raw string).
I would like to select or filter on those metadata property.
This is something like this :
START movie=node:TYPE_INDEX(Type = 'MOVIE') // Start with the reference
MATCH movie-[t:TAG]->tag
WHERE collect(movie.Metadata).RatingPress > 3
RETURN distinct movie.Label
And metadata are something like this :
{"RatingPress" : "0","RatingSpectator" : 3"}
I have expected to use collect function in order to call the property like this :
collect(movie.Metadata).RatingPress
But, of course it fails...
Is this a way to bind some json string from a node property with cypher ?
Thanks for your help
That's going against the principles of properties. Why not set the properties in the JSON metadata directly on the node?
But to answer your question:
No, cypher has no knowledge about JSON.
We treat the entire Node as a JSON blob. Since Neo4j doesn't support hierarchical properties, we flatten out the JSON into delimited property names on save and unflatten them on read. You can then form Cypher queries on (for example) property name "foo.bar.baz". The queries tend to look a bit funky because you'll need to quote them using single back quotes, but it works.
I'm trying to parse a grails parameter map to a Json String, and then back to a parameter map. (For saving html form entries with constraint-violations)
Everything is fine as long as there is no hasMany relationship in the parameter-map.
I'm using
fc.parameter = params as JSON
to save the params as JSON String.
Later I'm trying to rebuild the parameter map and create a new Domain-Object with it:
new Foo(JSON.parse(fc.parameter))
Everything is fine using only 1:1 relationships (states).
[states:2, listSize:50, name:TestFilter]
But when I try to rebuild a params-map with multi-select values (states)
[states:[1,2], listSize:50, name:TestFilter]
I'm getting this IllegalStateException:
Failed to convert property value of type org.codehaus.groovy.grails.web.json.JSONArray to required type java.util.Set for property states; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [de.gotosec.approve.State] for property states[0]: no matching editors or conversion strategy found
I tried to use this, but without success:
JSON.use("deep") {
new Foo(JSON.parse(fc.parameter))
}
You can use JsonSlurper instead of the converters.JSON of grails, it maps JSON objects to Groovy Maps. I think this link also might help you.
Edit: Now, if the problem is binding the params map to your domain, you should try using bindData() method, like:
bindData(foo, params)
Note that this straightforward use is only if you're calling bindData inside a controller.
What seems to be happening in your case is that Grails is trying to bind a concrete type of List (ArrayList in the case of JsonSlurper and JSONArray in the case of converters.JSON) into a Set of properties (which is the default data structure for one-to-many associations). I would have to take a look at your code to confirm that. But, as you did substitute states: [1,2] for a method of your app, try another test to confirm this hypothesis. Change:
states:[1,2]
for
states:[1,2] as Set
If this is really the problem and not even bindData() works, take a look at this for a harder way to make it work using object marshalling and converters.JSON. I don't know if it's practical for you to use it in your project, but it sure works nicely ;)