BAEL-3372 - Guide to Linux jq command for JSON formatting

Author: Jonathan Cook

linux-bash/json/src/main/bash/fruit.json

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+{"fruit":{"name":"apple","color":"green","price":1.20}}

linux-bash/json/src/main/bash/fruits.json

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+[
+  {
+    "name": "apple",
+    "color": "green",
+    "price": 1.2
+  },
+  {
+    "name": "banana",
+    "color": "yellow",
+    "price": 0.5
+  },
+  {
+    "name": "kiwi",
+    "color": "green",
+    "price": 1.25
+  }
+] 

linux-bash/json/src/main/bash/jq.sh

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+#!/bin/bash
+
+#3.1. Beautify JSON
+echo '{"fruit":{"name":"apple","color":"green","price":1.20}}' | jq '.'
+jq '.' fruit.json
+curl http://api.open-notify.org/iss-now.json | jq '.'
+
+#3.2. Accessing Properties
+jq '.fruit' fruit.json
+jq '.fruit.color' fruit.json
+jq '.fruit.color,.fruit.price' fruit.json
+echo '{ "with space": "hello" }' | jq '."with space"'
+
+#4.1. Iteration
+echo '["x","y","z"]' | jq '.[]'
+jq '.[] | .name' fruits.json
+jq '.[].name' fruits.json
+
+#4.2. Accessing By Index
+jq '.[1].price' fruits.json
+
+#4.3. Slicing
+echo '[1,2,3,4,5,6,7,8,9,10]' | jq '.[6:9]'
+echo '[1,2,3,4,5,6,7,8,9,10]' | jq '.[:6]' | jq '.[-2:]'
+
+#5.1. Getting Keys
+jq '.fruit | keys' fruit.json
+
+#5.2. Returning the Length
+jq '.fruit | length' fruit.json
+jq '.fruit.name | length' fruit.json
+
+#5.3. Mapping Values
+jq 'map(has("name"))' fruits.json
+jq 'map(.price+2)' fruits.json
+
+#5.4. Min and Max
+jq '[.[].price] | min' fruits.json
+jq '[.[].price] | max' fruits.json
+
+#5.5. Selecting Values
+jq '.[] | select(.price>0.5)' fruits.json
+jq '.[] | select(.color=="yellow")' fruits.json
+jq '.[] | select(.color=="yellow" and .price>=0.5)' fruits.json
+
+#5.6. Support For RegEx
+jq '.[] | select(.name|test("^a.")) | .price' fruits.json
+
+#5.7. Find Unique Values
+jq 'map(.color) | unique' fruits.json
+
+#5.8. Deleting Keys From JSON
+jq 'del(.fruit.name)' fruit.json
+
+# 6. Transforming
+jq '.query.pages | [.[] | map(.) | .[] | {page_title: .title, page_description: .extract}]' wikipedia.json

linux-bash/json/src/main/bash/wikipedia.json

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+{
+  "query": {
+    "pages": [
+      {
+        "21721040": {
+          "pageid": 21721040,
+          "ns": 0,
+          "title": "Stack Overflow",
+          "extract": "Some interesting text about Stack Overflow"
+        }
+      },
+      {
+        "21721041": {
+          "pageid": 21721041,
+          "ns": 0,
+          "title": "Baeldung",
+          "extract": "A great place to learn about Java"
+        }
+      }
+    ]
+  }
+}