Filter List of Map Using Enum. Reduce
I Have a Map as %Subject { Sub_Id: 1, Content: %{ Sub_Name: "Oracle", Type: "Code", }, Publisher: "Quantum", Ouby_Id: "Afc5A6E23208", Region: "Usa", } I Have a...
I have a map as
%Subject
{
sub_id: 1,
content: %{
sub_name: "oracle",
type: "code",
},
publisher: "quantum",
ouby_id: "afc5a6e23208",
region: "USA",
}
I have a list as follows
[
%user{id: 4, name: "kane", status: "A"},
%user{id: 3, name: "Harry", status: "P"},
%user{id: 5, name: "Tom", status: "A"}
]
I want to filter User with status: "A" and create a new map as
[
%{id: 4,name: "kane", sub_id: 1, sub_name: "oracle"},
%{id: 5,name: "Tom", sub_id: 1, sub_name: "oracle"}
]
Can anyone please help me with this?
Thank you.
2 Answers
Despite the solution by Adam is perfectly correct, I’d better go with .
[
%{id: 4, name: "kane", status: "A"},
%{id: 3, name: "Harry", status: "P"},
%{id: 5, name: "Tom", status: "A"}
]
|> Enum.reduce([], fn
%{status: "A"} = elem, acc ->
elem =
elem
|> Map.take(~w|id name|a)
|> Map.put(:sub_id, subject.sub_id),
|> Map.put(:sub_name, subject.content.sub_name)
[elem | acc]
_, acc ->
acc
end)
|> Enum.reverse()
I think using a combination of filter and map would be better here. You didn't explain why Subject was necessary, so I just hardcoded the values you said would always be the same.
[
%User{id: 4, name: "kane", status: "A"},
%User{id: 3, name: "Harry", status: "P"},
%User{id: 5, name: "Tom", status: "A"}
]
|> Stream.filter(&(&1.status == "A"))
|> Enum.map(fn map ->
%{
id: map.id,
name: map.name,
sub_id: 1,
sub_name: "oracle"
}
end)
Result:
[
%{id: 4, name: "kane", sub_id: 1, sub_name: "oracle"},
%{id: 3, name: "Harry", sub_id: 1, sub_name: "oracle"},
%{id: 5, name: "Tom", sub_id: 1, sub_name: "oracle"}
]
Robert Thorne covers electric vehicle innovations, autonomous driving systems, global mobility trends, and automotive engineering developments.
