SweetXml: Parse into a list of mappings

Questions / Help
1

Heya,

I’m trying to use SweetXml to parse an XML like this one:

<?xml version="1.0"?>
<lecturers>
  <lecturer>
    <key>75A7EBE3323C0EB1</key>
    <firstName>Albert</firstName>
    <lastName>Einstein</lastName>
  </lecturer>
  <lecturer>
    <key>619D3EDCF60E5A14</key>
    <firstName>Niels</firstName>
    <lastName>Bohr</lastName>
  </lecturer>
</lecturers>

… and I would like to get a list of mappings in return. Now, I actually already found a way to do so, but it seems needlessly complicated:

iex(26)> ls = """
...(26)> <?xml version="1.0"?>
...(26)> <lecturers>
...(26)>   <lecturer>
...(26)>     <key>75A7EBE3323C0EB1</key>
...(26)>     <firstName>Albert</firstName>
...(26)>     <lastName>Einstein</lastName>
...(26)>   </lecturer>
...(26)>   <lecturer>
...(26)>     <key>619D3EDCF60E5A14</key>
...(26)>     <firstName>Niels</firstName>
...(26)>     <lastName>Bohr</lastName>
...(26)>   </lecturer>
...(26)> </lecturers>
...(26)> """
"<?xml version=\"1.0\"?>\n<lecturers>\n  <lecturer>\n    <key>75A7EBE3323C0EB1</key>\n    <firstName>Albert</firstName>\n    <lastName>Einstein</lastName>\n  </lecturer>\n  <lecturer>\n    <key>619D3EDCF60E5A14</key>\n    <firstName>Niels</firstName>\n    <lastName>Bohr</lastName>\n  </lecturer>\n</lecturers>\n"
iex(27)> ls |> xpath(~x"/lecturers/lecturer"l, key: ~x"./key/text()"s, firstName: ~x"./firstName/text()"s, lastName: ~x"./lastName/text()"s)
[
  %{key: "75A7EBE3323C0EB1", firstName: "Albert", lastName: "Einstein"},
  %{key: "619D3EDCF60E5A14", firstName: "Niels", lastName: "Bohr"}
]

For every key/node, I have to specify it twice, and verbosely so (~x"./…/text()"s is a handful), while ideally I would like to do something like dwim(ls, ~x"/lecturers/lecturer"l, [:key, :firstName, :lastName]).

Am I just holding SweetXml wrong? Its documentation wasn’t really helpful to me, and I’m also a very novice Elixir programmer, so maybe I’m just overlooking something trivial.

Thanks!

2

I’m pretty sure this is the least-verbose way to get what you want:

ls
# Parse a list of `lecturer` nodes
|> xpath(~x"./lecturer"l) 
# Parse the desired values from each node
|> Enum.map(fn node ->
  xmap(node,
    key: ~x"./key/text()"s,
    first_name: ~x"./firstName/text()"s,
    last_name: ~x"./lastName/text()"s)
  end)

For your example, this will produce:

[
  %{first_name: "Albert", key: "75A7EBE3323C0EB1", last_name: "Einstein"},
  %{first_name: "Niels", key: "619D3EDCF60E5A14", last_name: "Bohr"}
]