ImmutableJS-过滤嵌套Map {List（Map {…}）}

Question

Given the following data structure.

 let hall = Map({ tables: Map({ t1: Map({ playlist: List( Map({ songid: 'target' }) ) }), t2: Map({ playlist: List( Map({ songid: 'not me' }) ) }) }) }); 

How do I iterate over each table (t1, t2, ...) and remove the item in the list with songid === 'target' so that I end up with:

 let expected_hall = Map({ tables: Map({ t1: Map({ playlist: List() }), t2: Map({ playlist: List( Map({ songid: 'not me' }) ) }) }) }); 

Tried the following to no avail:

 let res = hall; hall.get('tables').entrySeq().forEach(e => { res = res.updateIn(['tables', e[0], 'playlist'], list => list.filter(songinfo => songinfo.songid === 'target')); }); // or using hall.get('tables').map(...) 

Appreciate for all the help given.

Answer 1

 let hall = Map({ tables: Map({ t1: Map({ playlist: List.of( Map({ songid: 'target' }) ) }), t2: Map({ playlist: List.of( Map({ songid: 'not me' }) ) }) }) }); 

The way you've used List, it should be List.of(...) or List([])

I would do it like this:

 const hall2 = hall.update("tables", tables => ( tables.map(table => ( table.update("playlist", playlist => playlist.filter(p => p.get("songid")!=="not me")) )) )); 

You update the tables property, iterate over each table, update the playlist property and filter the playlist by each item on not being "not me"

Answer 2

Docs of List#filter

Returns a new List with only the values for which the predicate function returns true.

So here we have to return which list whom songid IS NOT target

 let res = hall; hall.get('tables').keySeq().forEach(e => { res = res.updateIn(['tables', e, 'playlist'], list => list.filter(info => info.get("songid") !== "target")); });