Provide an alternative to Uri#queryParameters which returns the values as a list

[DartBot]

This issue was originally filed by @MarkBennett

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What steps will reproduce the problem?

1. Parse a Uri with a query string. (i.e. Uri.fromString("http://test.com/?age=32&name=Mark)
2. Parse and transform uri query string manually.
3. Be sad when I wasted extra lines.

What is the expected output? What do you see instead?

I expected to be able to call uri.params to access a Map of the params. This would also safely escape parameters, etc.

What version of the product are you using? On what operating system?

Version 0.1.0.201204121423, Build 6479
Dart SDK version 6478, Dartium version

Please provide any additional information below.

This issue arose as the result of a forum post...

https://groups.google.com/a/dartlang.org/group/misc/browse_thread/thread/b4f94de2bb6456cb#

[madsager]

Added Area-Library, Triaged labels.

[DartBot]

This comment was originally written by @seaneagan

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I would suggest:

final Map<String, String> query;
final String queryString; // rename existing Uri#query

[DartBot]

This comment was originally written by [email protected]

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Note that you can have more params of the same name in the query. It's the same case as HTTP headers -- when we get a [List]MultiMap, we should use that, until then, Map<String, List<String>>.

[DartBot]

This comment was originally written by @MarkBennett

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I agree that this will need MultiMap support or something similair in the future. Another option would be to collect multiple values into a List under the same key in the Map.

I'll take a look at how other frameworks handle this for comparison.

[DartBot]

This comment was originally written by [email protected]

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For things like OpenSearch patterns I think you would also need to test for multiple and empty query terms. Like in:

foo.org?qt1=p1,p2,p3&qt2=&qt3=p4

[peter-ahe-google]

Sounds reasonable and something which can safely be added later.

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Added this to the Later milestone.

[justinfagnani]

We've seen a lot of code out there to parse query strings for Uri and Window.location. Since query strings are rarely useful without parsing, it'd be nice to get this solved sooner.

Rather than waiting on MultiMap, we can handle this like HttpHeaders and use [] to get the list of values and value() to get a single value.

Pete has a patch to add add query parsing to Location, but we're thinking it'd be much better on Uri, with a asUri() method on Location.

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cc @blois.
Added Library-Uri label.

[justinfagnani]

Marked this as blocking #6679.

[lrhn]

cc @sgjesse.
Removed Type-Defect label.
Added Type-Enhancement label.

[sgjesse]

A Uri instance now has the getter queryParameters. It is a Map<String, String> and there is only one value for each name.

[andersjohnsen]

Changed the title to: "Make Uri#queryParameters return a MultiMap".

[lrhn]

Removed Library-Uri label.
Added Library-Core label.

[kevmoo]

We cannot change the type of queryParamaters now, but we could imagine another member on Uri which provides access to individual values as a list.

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Changed the title to: "Provide an alternative to Uri#queryParameters which returns the values as a list".

[kasperl]

Removed this from the Later milestone.
Added Oldschool-Milestone-Later label.

[kasperl]

Removed Oldschool-Milestone-Later label.

[lrhn]

Now also has Uri.queryParametersAll that returns Map<String,List<String>>