Unexpected token & in JSON when parsing object from string

Question

I tried to parse data from elixir map converted to JSON using Poison.encode!(), in any case I got error:

Unexpected token & in JSON at position 1

How to escape double quotes inside this string, to prevent adding "&quote;"?

Initial data:

%{"node_10_10@172.17.0.11" => ["40000000-5fffffff", "a0000000-bfffffff"],
  "node_1_10@172.17.0.2" => ["20000000-3fffffff", "a0000000-bfffffff"],
  "node_2_10@172.17.0.3" => ["20000000-3fffffff", "80000000-9fffffff"],
  "node_3_10@172.17.0.4" => ["20000000-3fffffff", "80000000-9fffffff",
   "e0000000-ffffffff"],
  "node_4_10@172.17.0.5" => ["00000000-1fffffff", "80000000-9fffffff",
   "e0000000-ffffffff"],
  "node_5_10@172.17.0.6" => ["00000000-1fffffff", "60000000-7fffffff",
   "e0000000-ffffffff"],
  "node_6_10@172.17.0.7" => ["00000000-1fffffff", "60000000-7fffffff",
   "c0000000-dfffffff"],
  "node_7_10@172.17.0.8" => ["60000000-7fffffff", "c0000000-dfffffff"],
  "node_8_10@172.17.0.9" => ["40000000-5fffffff", "c0000000-dfffffff"],
  "node_9_10@172.17.0.10" => ["40000000-5fffffff", "a0000000-bfffffff"]}

Mapped to new structure, using this method inside controller:

defp map_shards(nodes, :nodes), do: %{"nodes": Enum.map(nodes, fn{k, v} -> %{"node": k, "shards": v} end)}    

Call inside index action:

nodes = map_shards(resp["by_node"], :nodes)

Now I have map as this:

%{nodes: [%{node: "node_10_10@172.17.0.11", shards: ["40000000-5fffffff", "a0000000-bfffffff"]}, %{node: "node_1_10@172.17.0.2", shards: ["20000000-3fffffff", "a0000000-bfffffff"]}, %{node: "node_2_10@172.17.0.3", shards: ["20000000-3fffffff", "80000000-9fffffff"]}, %{node: "node_3_10@172.17.0.4", shards: ["20000000-3fffffff", "80000000-9fffffff", "e0000000-ffffffff"]}, %{node: "node_4_10@172.17.0.5", shards: ["00000000-1fffffff", "80000000-9fffffff", "e0000000-ffffffff"]}, %{node: "node_5_10@172.17.0.6", shards: ["00000000-1fffffff", "60000000-7fffffff", "e0000000-ffffffff"]}, %{node: "node_6_10@172.17.0.7", shards: ["00000000-1fffffff", "60000000-7fffffff", "c0000000-dfffffff"]}, %{node: "node_7_10@172.17.0.8", shards: ["60000000-7fffffff", "c0000000-dfffffff"]}, %{node: "node_8_10@172.17.0.9", shards: ["40000000-5fffffff", "c0000000-dfffffff"]}, %{node: "node_9_10@172.17.0.10", shards: ["40000000-5fffffff", "a0000000-bfffffff"]}]}

JS code, with parser call inside template .eex:

var theData = ("<%= Poison.Encoder.encode(@nodes, []) %>");
theData = JSON.parse(theData);

What I see in JS console:

var theData = ("{"nodes":[{"shards":["40000000-5fffffff","a0000000-bfffffff"],"node":"node_10_10@172.17.0.11"},{"shards":["20000000-3fffffff","a0000000-bfffffff"],"node":"node_1_10@172.17.0.2"},{"shards":["20000000-3fffffff","80000000-9fffffff"],"node":"node_2_10@172.17.0.3"},{"shards":["20000000-3fffffff","80000000-9fffffff","e0000000-ffffffff"],"node":"node_3_10@172.17.0.4"},{"shards":["00000000-1fffffff","80000000-9fffffff","e0000000-ffffffff"],"node":"node_4_10@172.17.0.5"},{"shards":["00000000-1fffffff","60000000-7fffffff","e0000000-ffffffff"],"node":"node_5_10@172.17.0.6"},{"shards":["00000000-1fffffff","60000000-7fffffff","c0000000-dfffffff"],"node":"node_6_10@172.17.0.7"},{"shards":["60000000-7fffffff","c0000000-dfffffff"],"node":"node_7_10@172.17.0.8"},{"shards":["40000000-5fffffff","c0000000-dfffffff"],"node":"node_8_10@172.17.0.9"},{"shards":["40000000-5fffffff","a0000000-bfffffff"],"node":"node_9_10@172.17.0.10"}]}");

theData = JSON.parse(theData);

Answer 1

You need to disable the automatic HTML escaping when injecting encoded JSON like that. You also don't need the surrounding " or brackets.

var theData = <%= raw Poison.Encoder.encode(@nodes, []) %>;

There's no need to call JSON.parse anymore, theData will be set to the value itself, not a string containing a JSON.