Merging arrays of dictionaries - json

Question

Given the following two arrays of dictionaries, how can I merge them such that the resulting array of dictionaries contains only those dictionaries whose version is greatest?
data1 = [{'id': 1, 'name': 'Oneeee', 'version': 2},
{'id': 2, 'name': 'Two', 'version': 1},
{'id': 3, 'name': 'Three', 'version': 2},
{'id': 4, 'name': 'Four', 'version': 1},
{'id': 5, 'name': 'Five', 'version': 1}]
data2 = [{'id': 1, 'name': 'One', 'version': 1},
{'id': 2, 'name': 'Two', 'version': 1},
{'id': 3, 'name': 'Threeee', 'version': 3},
{'id': 6, 'name': 'Six', 'version': 2}]
The merged result should look like this:
data3 = [{'id': 1, 'name': 'Oneeee', 'version': 2},
{'id': 2, 'name': 'Two', 'version': 1},
{'id': 3, 'name': 'Threeee', 'version': 3},
{'id': 4, 'name': 'Four', 'version': 1},
{'id': 5, 'name': 'Five', 'version': 1},
{'id': 6, 'name': 'Six', 'version': 2}]

Answer 1

How about the following:
//define data1 and Data2
var data1 = new[]{
new {id = 1, name = "Oneeee", version = 2},
new {id = 2, name = "Two", version = 1},
new {id = 3, name = "Three", version = 2},
new {id = 4, name = "Four", version = 1},
new {id = 5, name ="Five", version = 1}
};
var data2 = new[] {
new {id = 1, name = "One", version = 1},
new {id = 2, name = "Two", version = 1},
new {id = 3, name = "Threeee", version = 3},
new {id = 6, name = "Six", version = 2}
};
//create a dictionary to handle lookups
var dict1 = data1.ToDictionary (k => k.id);
var dict2 = data2.ToDictionary (k => k.id);
// now query the data
var q = from k in dict1.Keys.Union(dict2.Keys)
select
dict1.ContainsKey(k) ?
(
dict2.ContainsKey(k) ?
(
dict1[k].version > dict2[k].version ? dict1[k] : dict2[k]
) :
dict1[k]
) :
dict2[k];
// convert enumerable back to array
var result = q.ToArray();
Alternative solution that is database friendly if data1 and data2 are tables....
var q = (
from d1 in data1
join d2 in data2 on d1.id equals d2.id into data2j
from d2j in data2j.DefaultIfEmpty()
where d2j == null || d1.version >= d2j.version
select d1
).Union(
from d2 in data2
join d1 in data1 on d2.id equals d1.id into data1j
from d1j in data1j.DefaultIfEmpty()
where d1j == null || d2.version > d1j.version
select d2
);
var result = q.ToArray();

Answer 2

Assume you have some class like (JSON.NET attributes used here):
public class Data
{
[JsonProperty("id")]
public int Id { get; set; }
[JsonProperty("name")]
public string Name { get; set; }
[JsonProperty("version")]
public int Version { get; set; }
}
You can parse you JSON to arrays of this Data objects:
var str1 = #"[{'id': 1, 'name': 'Oneeee', 'version': 2},
{'id': 2, 'name': 'Two', 'version': 1},
{'id': 3, 'name': 'Three', 'version': 2},
{'id': 4, 'name': 'Four', 'version': 1},
{'id': 5, 'name': 'Five', 'version': 1}]";
var str2 = #"[{'id': 1, 'name': 'One', 'version': 1},
{'id': 2, 'name': 'Two', 'version': 1},
{'id': 3, 'name': 'Threeee', 'version': 3},
{'id': 6, 'name': 'Six', 'version': 2}]";
var data1 = JsonConvert.DeserializeObject<Data[]>(str1);
var data2 = JsonConvert.DeserializeObject<Data[]>(str2);
So, you can concat these two arrays, group data items by id and select from each group item with highest version:
var data3 = data1.Concat(data2)
.GroupBy(d => d.Id)
.Select(g => g.OrderByDescending(d => d.Version).First())
.ToArray(); // or ToDictionary(d => d.Id)
Result (serialized back to JSON):
[
{ "id": 1, "name": "Oneeee", "version": 2 },
{ "id": 2, "name": "Two", "version": 1 },
{ "id": 3, "name": "Threeee", "version": 3 },
{ "id": 4, "name": "Four", "version": 1 },
{ "id": 5, "name": "Five", "version": 1 },
{ "id": 6, "name": "Six", "version": 2 }
]