C#•2y ago

❔ How to join 3 collections?

I have following logic:

var territoriesIDs = _parameters.TerritoriesIDs;

var accessGroups = await _accessGroupClient.GetByTerritoriesIds( territoriesIDs );
var accessGroupsIds = accessGroups.Select( accessGroup => accessGroup.Id );

var departments = await _departmentClient.GetByAccessGroupsIds( accessGroupsIds );
var departmentsIds = departments.Select( department => department.Id );

var subjects = await _subjectClient.GetByDepartmentsIds( departmentsIds );

var territoriesIDs = _parameters.TerritoriesIDs;

var accessGroups = await _accessGroupClient.GetByTerritoriesIds( territoriesIDs );
var accessGroupsIds = accessGroups.Select( accessGroup => accessGroup.Id );

var departments = await _departmentClient.GetByAccessGroupsIds( accessGroupsIds );
var departmentsIds = departments.Select( department => department.Id );

var subjects = await _subjectClient.GetByDepartmentsIds( departmentsIds );

I'd like to join accessGroups, departments, subjects, and get some properties from that collections How can I do it?

6 Replies

SWEETPONYOP•2y ago

Also I need to group by territory

Denis•2y ago

If you wish to perform an SQL like join, try this:

Enumerable.Join(listA, listB, a=>a.id, b=>b.id, (a,b) =>(a,b)).ToList()

Enumerable.Join(listA, listB, a=>a.id, b=>b.id, (a,b) =>(a,b)).ToList()

source: https://www.reddit.com/r/csharp/comments/mxvsoj/comment/gvrpzvl/?utm_source=share&utm_medium=web2x&context=3

r/csharp - Comment by u/ropewalker on ”Linq pairing two Lists of ...

16 votes and 10 comments so far on Reddit

Denis•2y ago

You can use the .Join extension method to combine two lists into a new list of a different type, e.g., a value tuple. After performing your joins you can select the properties that you need, group, whatever

SWEETPONYOP•2y ago

but I have 3 lists

Denis•2y ago

so first join a and b then join the result with c

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ How to join 3 collections?

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