JSONQ - JSON query utility.

Author: abs

Emakefile

@@ -0,0 +1,6 @@
+{'src/*',
+ [{outdir, "ebin"},
+  compressed,
+  debug_info,
+  strip
+ ]}.

Makefile

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+#!/usr/bin/make -f
+
+BEAMFILES := $(wildcard ebin/*.beam) $(wildcard test/*.beam)
+
+all: build
+
+build: ebin/$(APPFILE)
+	erl -make
+
+clean:
+	-rm -rf ebin/$(APPFILE) $(BEAMFILES)
+
+test: build
+	erlc -W +debug_info +compressed +strip -o test/ test/*.erl
+	erl -noshell -pa ebin -pa test -eval "query_tests:test()" -eval "init:stop()"

README.md

@@ -1,2 +1,117 @@
-jsonq
-=====
+Querying JSON Terms
+-------------------
+
+JSON:
+
+    {"store": {
+        "books": [
+            {
+                "category": "fiction",
+                "author": "J. R. R. Tolkien",
+                "title": "The Lord of the Rings",
+                "isbn": "0-395-19395-8",
+                "price": 22.99
+            },
+            {
+                "category": "fiction",
+                "author": ["Arkady N. Strugatsky", "Boris N. Strugatsky"],
+                "title": "Monday Begins on Saturday",
+                "isbn": "0-000-000000-0",
+                "price": 22.99
+            }
+        ],
+        "bicycle": {
+          "color": "red",
+          "price": 19.95
+        }
+    }}
+
+Erlang JSON term:
+
+    Json = {[{<<"store">>,
+        {[{<<"books">>, [
+            {[
+                {<<"category">>,<<"fiction">>},
+                {<<"author">>,<<"J. R. R. Tolkien">>},
+                {<<"title">>,<<"The Lord of the Rings">>},
+                {<<"isbn">>,<<"0-395-19395-8">>},
+                {<<"price">>,22.99}
+            ]},
+            {[
+                {<<"category">>,<<"fiction">>},
+                {<<"author">>, [<<"Arkady N. Strugatsky">>,<<"Boris N. Strugatsky">>]},
+                {<<"title">>,<<"Monday Begins on Saturday">>},
+                {<<"isbn">>,<<"0-000-000000-0">>},
+                {<<"price">>,22.99}
+            ]}
+        ]},
+        {<<"bicycle">>, {[
+            {<<"color">>,<<"red">>},
+            {<<"price">>,19.95}
+        ]}
+    }]}}]}.
+
+Query example 1:
+
+    jsonq:q([<<"store">>], Json).
+
+    {[{<<"books">>, [
+        {[
+            {<<"category">>,<<"fiction">>},
+            {<<"author">>,<<"J. R. R. Tolkien">>},
+            {<<"title">>,<<"The Lord of the Rings">>},
+            {<<"isbn">>,<<"0-395-19395-8">>},
+            {<<"price">>,22.99}
+        ]},
+        {[
+            {<<"category">>,<<"fiction">>},
+            {<<"author">>, [<<"Arkady N. Strugatsky">>,<<"Boris N. Strugatsky">>]},
+            {<<"title">>,<<"Monday Begins on Saturday">>},
+            {<<"isbn">>,<<"0-000-000000-0">>},
+            {<<"price">>,22.99}
+        ]}
+    ]}
+
+Query example 2:
+
+    jsonq:q([<<"store">>, <<"books">>], Json).
+    [
+        {[
+            {<<"category">>,<<"fiction">>},
+            {<<"author">>,<<"J. R. R. Tolkien">>},
+            {<<"title">>,<<"The Lord of the Rings">>},
+            {<<"isbn">>,<<"0-395-19395-8">>},
+            {<<"price">>,22.99}
+        ]},
+        {[
+            {<<"category">>,<<"fiction">>},
+            {<<"author">>, [<<"Arkady N. Strugatsky">>,<<"Boris N. Strugatsky">>]},
+            {<<"title">>,<<"Monday Begins on Saturday">>},
+            {<<"isbn">>,<<"0-000-000000-0">>},
+            {<<"price">>,22.99}
+        ]}
+    ]
+
+Query example 3:
+
+    jsonq:q([<<"store">>, <<"books">>, 0], Json).
+
+    {[
+        {<<"category">>,<<"fiction">>},
+        {<<"author">>,<<"J. R. R. Tolkien">>},
+        {<<"title">>,<<"The Lord of the Rings">>},
+        {<<"isbn">>,<<"0-395-19395-8">>},
+        {<<"price">>,22.99}
+    ]}
+
+Query example 4:
+
+    jsonq:q([<<"store">>, <<"books">>, 1, <<"author">>, 1], Json).
+
+    <<"Boris N. Strugatsky">>
+
+Query example 5:
+
+    jsonq:q([<<"store">>, <<"toys">>], Json).
+
+    undefined

rebar.config

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+{erl_opts, [warnings_as_errors]}.

src/jsonq.erl

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+-module(jsonq).
+
+-export([q/2]).
+
+q(_, undefined) ->
+    undefined;
+q([], Obj) ->
+    Obj;
+q([Key | Rest], {Obj}) ->
+    q(Rest, proplists:get_value(Key, Obj));
+q([Index | _Rest], []) when is_integer(Index) ->
+    undefined;
+q([Index | Rest], Obj) when is_integer(Index), is_list(Obj) ->
+    case Index < length(Obj) of
+        true -> q(Rest, lists:nth(Index + 1, Obj));
+        false -> undefined
+    end;
+q([Key | Rest], Obj) when is_list(Obj) ->
+    q(Rest, proplists:get_all_values(Key, Obj)).