jq.cr
thin JSON::Any wrapper to emulate jq for Crystal.
see Wiki for examples
breaking changes
- v0.5.0 : (breaking-change) mapping: parse
Timewithout formats.
crystal versions
- v0.5.1 : 0.24 or lower
- v0.6.0 : 0.25 .. 0.27
- v1.0.0 : 0.27 .. 1.1.1
Usage
- For example, here is a Grafana request data.
{
"panelId":1,
"range":{"from":"2016-09-02T13:32:09.981Z","to":"2016-09-02T14:17:34.306Z"},
"rangeRaw":{"from":"2016-09-02T13:32:09.981Z","to":"2016-09-02T14:17:34.306Z"},
"interval":"2s",
"targets":[{"target":"cpu","refId":"A"},{"target":"mem","refId":"B"}],
"format":"json",
"maxDataPoints":1299
}Parse in Functional way
- Just call 'Jq#[]` with query path.
require "jq"
jq = Jq.new(str)
jq[".range.from"].as_s # => "2016-09-02T13:32:09.981Z"
jq[".targets[].target"].as_a # => ["cpu","mem"]
jq[".format"].as_s # => "json"
jq[".maxDataPoints"].as_i # => 1299
jq[".xxx"] # Jq::NotFound("`.xxx' Missing hash key: "xxx")
jq[".xxx"]? # => nil- See
spec/fixtures/*files for further usage, or trycrystal spec -vfor full features
Auto parsing and casting by mapping
- looks like
JSON.mappingexcept this requires Tuple(type, json_path) for its arg. - NOTE: use
Int64rather thanInt32for Integer
require "jq"
class Request
Jq.mapping({
from: {Time, ".range.from"},
targets: {Array(String), ".targets[].target"},
format: String,
max: {Int64, ".maxDataPoints"},
})
end
req = Request.from_json(str)
req.from # => Time.new(2016,9,2,13,32,9,981)
req.targets # => ["cpu","mem"]
req.format # => "json"
req.max # => 1299
req.to_h["max"] # => 1299
req = Request.from_json("{}")
req.max # Jq::NotFound(key: "max")
req.max? # => nildefault value
- override
default_XXXto customize the behaviour of missingXXX
require "jq"
class User
Jq.mapping({
name: String,
})
def default_name
"(no name)"
end
end
user = User.from_json("{}")
user.name # => "(no name)"custom builder
- override
build_XXX(jq : Jq, hint : String)to customize the behaviour of buildingXXX
Imagine a strange API that returns a String if null, regardless of the value of Int type.
[
{"id": 1, "value": 10},
{"id": 2, "value": "--"}
]In this case, you can write your own logic to accept it by overriding build_count.
class Report
Jq.mapping({
id: Int32,
count: Int32?,
})
def build_count(jq : Jq, hint : String)
case jq.raw
when "--"
nil
else
jq.cast(Int32, hint)
end
end
end
reports = Array(Report).from_json <<-EOF
[
{"id": 1, "count": 10},
{"id": 2, "count": "--"}
]
EOF
reports.map(&.count?) # => [10, nil]Installation
Add this to your application's shard.yml:
dependencies:
jq:
github: maiha/jq.cr
version: 1.0.0CI
Run make test/x.x.x to test crystal-x.x.x. And to test all the versions, run ci.
$ make test/1.1.1
$ ./ciContributing
- Fork it ( https://github.com/maiha/jq.cr/fork )
- Create your feature branch (git checkout -b my-new-feature)
- Commit your changes (git commit -am 'Add some feature')
- Push to the branch (git push origin my-new-feature)
- Create a new Pull Request