Muuntaja is data-driven, allowing mostly everything to be defined via options. Muuntaja is created with muuntaja.core/create
function. It takes either an existing Muuntaja instance, options-map or nothing as a parameter.
(require '[muuntaja.core :as muuntaja])
;; with defaults
(def m (muuntaja/create))
;; with a muuntaja as prototype (no-op)
(muuntaja/create m)
;; with default options (same features, different instance)
(muuntaja/create muuntaja/default-options)
{:http {:extract-content-type extract-content-type-ring
:extract-accept-charset extract-accept-charset-ring
:extract-accept extract-accept-ring
:decode-request-body? (constantly true)
:encode-response-body? encode-collections}
:allow-empty-input? true
:return :input-stream
:default-charset "utf-8"
:charsets available-charsets
:default-format "application/json"
:formats {"application/json" json-format/json-format
"application/edn" edn-format/edn-format
"application/transit+json" transit-format/transit-json-format
"application/transit+msgpack" transit-format/transit-msgpack-format}}
As options are just data, normal Clojure functions can be used to modify them. Options are sanity checked at creation time. There are also the following helpers in the muuntaja.core
:
select-formats
: takes a sequence of formats selecting them and setting the first one as default format.transform-formats
takes an 2-arity function [format, format-options], which returns new format-options for that format. Returning nil
removes that format. Called for all registered formats.Easiest way is to add a :encoder-opts
key to the format with the options map as the value.
(def m
(muuntaja/create
(assoc-in
muuntaja/default-options
[:formats "application/json" :encoder-opts]
{:key-fn #(.toUpperCase (name %))})))
(slurp (muuntaja/encode m "application/json" {:kikka 42}))
;; "{\"KIKKA\":42}"
Check jsonista object-mapper docs for available options.
(def m
(muuntaja/create
(update-in
muuntaja/default-options
[:formats "application/transit+json"]
merge {:decoder-opts {:handlers transit-dates/readers}
:encoder-opts {:handlers transit-dates/writers}})))
:decoder-opts
is passed to reader
and :encoder-opts
to writer
.
Supporting only application/edn
and application/transit+json
formats.
(def m
(muuntaja/create
(-> muuntaja/default-options
(update
:formats
select-keys
["application/edn"
"application/transit+json"]))))
;; clojure.lang.ExceptionInfo Invalid default format application/json
Ups. That didn't work. The :default-format
is now illegal. This works:
(def m
(muuntaja/create
(-> muuntaja/default-options
(update
:formats
select-keys
["application/edn"
"application/transit+json"])
(assoc :default-format "application/edn"))))
Same with select-formats
:
(def m
(muuntaja/create
(muuntaja/select-formats
muuntaja/default-options
["application/json"
"application/edn"])))
(:default-format m)
; "application/edn"
We have to remove :decoder
key from all formats.
(def m
(muuntaja/create
(update
muuntaja/default-options
:formats
#(into
(empty %)
(map (fn [[k v]]
[k (dissoc v :decoder)]) %)))))
(muuntaja/encoder m "application/json")
;; #object[...]
(muuntaja/decoder m "application/json")
;; nil
Same with transform-formats
:
(def m
(muuntaja/create
(muuntaja/transform-formats
muuntaja/default-options
#(dissoc %2 :encoder))))
To be used with Ring 1.6.0+, with Pedestal & other streaming libs. We have
to change the :encoder
of the given formats:
(require '[muuntaja.format.json :as json-format])
(require '[muuntaja.format.transit :as transit-format])
(def m
(muuntaja/create
(-> muuntaja/default-options
(assoc-in
[:formats "application/json" :encoder 0]
json-format/make-streaming-json-encoder)
(assoc-in
[:formats "application/transit+json" :encoder 0]
(partial transit-format/make-streaming-transit-encoder :json))
(assoc-in
[:formats "application/transit+msgpack" :encoder 0]
(partial transit-format/make-streaming-transit-encoder :msgpack)))))
(muuntaja/encode m "application/json" {:kikka 2})
;; <<StreamableResponse>>
(slurp (muuntaja/encode m "application/json" {:kikka 2}))
; "{\"kikka\":2}"
If, for some reason, you want use the RegExps to match the content-type (like
ring-json
, ring-transit
& ring-middleware-format
do. We need just to add
a :matches
key to format with a regexp as a value. The following procudes loose
matching like in ring-middleware-format
:
(def m
(muuntaja/create
(-> muuntaja/default-options
(assoc-in [:formats "application/json" :matches] #"^application/(.+\+)?json$")
(assoc-in [:formats "application/edn" :matches] #"^application/(vnd.+)?(x-)?(clojure|edn)$")
;(assoc-in [:formats "application/msgpack" :matches] #"^application/(vnd.+)?(x-)?msgpack$")
;(assoc-in [:formats "application/x-yaml" :matches] #"^(application|text)/(vnd.+)?(x-)?yaml$")
(assoc-in [:formats "application/transit+json" :matches] #"^application/(vnd.+)?(x-)?transit\+json$")
(assoc-in [:formats "application/transit+msgpack" :matches] #"^application/(vnd.+)?(x-)?transit\+msgpack$"))))
((:negotiate-content-type m) "application/vnd.foobar+json; charset=utf-8")
;; #muuntaja.core.FormatAndCharset{:format "application/json", :charset "utf-8"}
See [[Creating new formats]].
Currently, both cheshire
& clojure-msgpack
allow new type encoders to be defined via Clojure protocol extensions. Importing a namespace could bring new type mappings or override existings without a warning, potentially breaking things. Ordering of the imports should not matter!
TODO: Make all options explicit.
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Juho Teperi, Unknown, Tommi Reiman & Martin KlepschEdit on GitHub
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