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JSONPath

RFC-9535 compliant JSONPath query evaluator for Elixir, with 100% passing rate for the JSONPath Compliance Test Suite

Installation

Add json_path to your list of dependencies in mix.exs:

def deps do

  [

    {:json_path, "~> 0.4"}

  ]

end

Usage

JSONPath supports string keys only.

You can pass the JSONPath query expression as a string

iex(1)> root = [%{"a" => %{"b" => "c"}}, %{"b" => %{"a" => 1}}]

iex(2)> query = "$..a"

iex(3)> JSONPath.values(root, query)

{:ok, [%{"b" => "c"}, 1]}

Or if you plan use the same query multiple times, you can build the expression once for better performance

iex(1)> {:ok, query} = JSONPath.build("$[1]")

iex(2)> JSONPath.values([], query)

{:ok, []}



iex(3)> JSONPath.values(["a", "b", "c"], query)

{:ok, ["b"]}

Attempting to build invalid JSONPath expressions returns helpful error messages

iex(1)> JSONPath.build("$[?length(@.elems)]")

{:error,

 %JSONPath.Error{

   type: :invalid_expression,

   expression: "length(@['elems'])",

   message: "comparison operator expected"

 }}



iex(2)> JSONPath.values([%{"name" => "Alice"}], "$[?match(@.name)]")

{:error,

 %JSONPath.Error{

   type: :invalid_expression,

   expression: "match(@['name'])",

   message: "got 1 argument but 'match' expects 2 arguments"

 }}

Retrieving node values, normalized paths or both

iex(1)> root = %{"people" => [

...>    %{"name" => "Alice", "age" => 20},

...>    %{"name" => "Bob", "age" => 30}

...>  ]}

iex(2)> query = "$.people[?@.age > 25]"

iex(3)> JSONPath.values(root, query)

{:ok, [%{"name" => "Bob", "age" => 30}]}



iex(4)> JSONPath.paths(root, query)

{:ok, ["$['people'][1]"]}



iex(5)> JSONPath.value_paths(root, query)

{:ok, [{%{"name" => "Bob", "age" => 30}, "$['people'][1]"}]}

Notes and considerations