ExJSONPointer

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hex.pm version

An Elixir implementation of RFC 6901 JSON Pointer for locating specific values within JSON documents.

Usage

The JSON pointer string syntax can be represented as a JSON string:

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => "hello"}}}, "/a/b/c")
"hello"

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => "hello"}}}, "/a/b")
%{"c" => "hello"}

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => [1, 2, 3]}}}, "/a/b/c")
[1, 2, 3]

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => [1, 2, 3]}}}, "/a/b/c/2")
3

iex> ExJSONPointer.resolve(%{"a" => [%{"b" => %{"c" => [1, 2]}}, 2, 3]}, "/a/2")
3

iex> ExJSONPointer.resolve(%{"a" => [%{"b" => %{"c" => [1, 2]}}, 2, 3]}, "/a/0/b/c/1")
2

or a URI fragment identifier:

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => "hello"}}}, "#/a/b/c")
"hello"

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => "hello"}}}, "#/a/b")
%{"c" => "hello"}

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => [1, 2, 3]}}}, "#/a/b/c")
[1, 2, 3]

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => [1, 2, 3]}}}, "#/a/b/c/2")
3

iex> ExJSONPointer.resolve(%{"a" => [%{"b" => %{"c" => [1, 2]}}, 2, 3]}, "#/a/2")
3

iex> ExJSONPointer.resolve(%{"a" => [%{"b" => %{"c" => [1, 2]}}, 2, 3]}, "#/a/0/b/c/1")
2

Some cases that a JSON pointer that references a nonexistent value:

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => "hello"}}}, "/a/b/d")
nil

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => [1, 2, 3]}}}, "/a/b/c/4")
nil

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => "hello"}}}, "#/a/b/d")
nil

iex> ExJSONPointer.resolve(%{"a" => %{"b" => %{"c" => [1, 2, 3]}}}, "#/a/b/c/4")
nil

Some cases that a JSON pointer has some empty reference tokens, and link a $ref test case from JSON Schema Test Suite(draft 2020-12) for reference.

iex> ExJSONPointer.resolve(%{"" => %{"" => 1}}, "/")
%{"" => 1} 

iex> ExJSONPointer.resolve(%{"" => %{"" => 1}}, "//")
1

iex> ExJSONPointer.resolve(%{"" => %{"" => 1, "b" => %{"" => 2}}}, "//b")
%{"" => 2}

iex> ExJSONPointer.resolve(%{"" => %{"" => 1, "b" => %{"" => 2}}}, "//b/")
2

iex> ExJSONPointer.resolve(%{"" => %{"" => 1, "b" => %{"" => 2}}}, "//b///")
nil

Invalid JSON pointer syntax:

iex> ExJSONPointer.resolve(%{"a" =>%{"b" => %{"c" => [1, 2, 3]}}}, "a/b")
{:error,
  "invalid JSON pointer syntax that not represented starts with `#` or `/`"}

iex> ExJSONPointer.resolve(%{"a" =>%{"b" => %{"c" => [1, 2, 3]}}}, "##/a")
{:error,
  "invalid URI fragment identifier"}

Please see the test cases for more examples.