Uri class throws error when queryParameters contains a key with a value: false? - dart

Question

I was working through some code, and noticed:
return new Uri(host: server, path: apiPath, query: query, queryParameters: queryParams);
This code is executed regularly throughout the application, and the only difference was queryParams. So i printed it out:
{Id:[1234], enabled:false}
shows it is a key:value set of: Id:List, enabled:boolean.
The stack trace i get is:
which shows the map and then the trace. #6 points to the above line.
It is looking at false... something with iterating false is what breaks this.

Answer 1

When dealing with the URI and query parameters, it is looking for numerics, lists, and strings but not booleans. In order to resolve this and allow it to function correctly, you will need to do:
{"enabled": false.toString()}
// or
{"enabled": "false"}
and the uri class will set the query parameter accordingly.
The Uri class is located in core library for Dart. When we are using it, we are passing in the created Uri object into an action for a client class,
Client client = new BrowserClient();
which accepts the url as a part of the parameters.
While looking at the errors above though, the Uri class ultimately is unable to properly parse a false value to an accepted value.
When looking at the Code Docs for Uri as per the Dart languages: https://api.dartlang.org/dev/1.25.0-dev.7.0/dart-core/Uri/Uri.html
The query component is set through either query or queryParameters. When query is used, the provided string should be a valid URI query, but invalid characters, other than general delimiters, will be escaped if necessary. When queryParameters is used the query is built from the provided map. Each key and value in the map is percent-encoded and joined using equal and ampersand characters. A value in the map must be either a string, or an Iterable of strings, where the latter corresponds to multiple values for the same key.
Which makes sense to say all values must be String or an Iterable of Strings. The only thing which I cant figure out is that in Dartpad, true and false have toString functions, and yet you can also pass numerics in there.
The only conclusion is that while it accepts Strings and Iterables of Strings, it will also parse ints and other numerics because they will explicitly check for that type as it is common to see in URI.
One would think that the URI would understand booleans since those are also common place, but that is yet to be seen since I cant take an explicit look at the source code for dartlang. I did however manage to look at the source code for it and narrowed it down. writeComponent points to _Uri._uriEncode but when looking at that function, there is no code as much as just a definition.
HTH.