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jq¤

Python Plugin

This operator is part of a Python Plugin Package. In order to use it, you need to install it, e.g. with cmemc.

jq is like sed for JSON data - you can use it to slice and filter and map and transform structured data with the same ease that sed, awk, grep and friends let you play with text.

In order to test jq expressions, you can use play.jqlang.org.

Basic concepts:¤

  • Filters separated by a comma will produce multiple independent outputs: ,
  • Will ignores error if the type is unexpected: ?
  • Array construction: []
  • Object construction: {}
  • Concatenate or Add: +
  • Difference of sets or Substract: -
  • Size of selected element: length
  • Pipes are used to chain commands in a similar fashion than bash: |

Dealing with JSON objects¤

  • Display all keys: keys
  • Adds + 1 to all items: map_values(.+1)
  • Delete a key: del(.foo)
  • Convert an object to array: to_entries | map([.key, .value])

Dealing with fields¤

  • Concatenate two fields: fieldNew=.field1+' '+.field2

Dealing with arrays: Slicing and Filtering¤

  • All: .[]
  • First: .[0]
  • Range: .[2:4]
  • First 3: .[:3]
  • Last 2: .[-2:]
  • Before Last: .[-2]
  • Select array of int by value: map(select(. >= 2))
  • Select array of objects by value: .[] | select(.id == "second")
  • Select by type: .[] | numbers

Types can be arrays, objects, iterables, booleans, numbers, normals, finites, strings, nulls, values and scalars.

Dealing with arrays: Mapping and Transforming¤

  • Add + 1 to all items: map(.+1)
  • Delete 2 items: del(.[1, 2])
  • Concatenate arrays: add
  • Flatten an array: flatten
  • Create a range of numbers: [range(2;4)]
  • Display the type of each item: map(type)
  • Sort an array of basic type: sort
  • Sort an array of objects: sort_by(.foo)
  • Group by a key - opposite to flatten: group_by(.foo)
  • Minimum value of an array: min (see also max, min_by(path_exp), max_by(path_exp))
  • Remove duplicates: unique or unique_by(.foo) or unique_by(length)
  • Reverse an array: reverse

Parameter¤

jq Expression¤

The jq program to apply to the input JSON string.

  • Datatype: string
  • Default Value: .

Output list with one item as string¤

  • Datatype: boolean
  • Default Value: true

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