Submitting URL encoded array of structured arguments.

[reygoch]

This might be slightly related to #62.

Let's say that I have these data types:

data Something = Something
    { field01 :: Text
    , field02 :: Text
    }

data StepInstruction = StepInstruction
    { id :: Int
    , order :: Int
    , description :: Text
    }

data Recipe = Recipe
    { id :: Int
    , name :: Text
    , something :: Something
    , instructions :: [StepInstruction]
    }

In PHP I could easily submit a form with such data type and get it back in the form of a nested array. Convention for submitting Recipe is as follows:

?id=0
&name=Recipe01

&instructions[0][id]=0
&instructions[0][order]=1
&instructions[0][description]=somedescription

&instructions[1][id]=1
&instructions[1][order]=2
&instructions[1][description]=someotherdescription

Currently Query flat and I'd have to do additional parsing on the argument names to get an array of structured arguments.

I'm not sure if this is a standard, but I've also seen the same convention in C#/MVC so I think it would be a good idea to support such feature, because I might want to add repeating "sub forms" to my main form that should be contained in array, and currently there is no good way to do that from what I can see.

Here is also an example of a form that might submit such query:

<form>
    <input type="hidden" name="id">
    <input type="text" name="name">

    <input type="text" name="something[field01]">
    <input type="text" name="something[field02]">

    <div>
        <input type="hidden" name="instructions[0][id]">
        <input type="number" name="instructions[0][order]">
        <input type="text" name="instructions[0][description]">
    </div>

    <div>
        <input type="hidden" name="instructions[1][id]">
        <input type="number" name="instructions[1][order]">
        <input type="text" name="instructions[1][description]">
    </div>

    <div>
        <input type="hidden" name="instructions[2][id]">
        <input type="number" name="instructions[2][order]">
        <input type="text" name="instructions[2][description]">
    </div>
</form>

Maybe QueryItem should look something like this:

data QueryItem
    = PlainValue ByteString
    | QueryItemList [QueryItem]
    | QueryItem (ByteString, Maybe QueryItem)

[aristidb]

Similar to what I said in #62, I am not in favor of changing the existing functions because that would break compatibility and also because this is not the most common way of using form inputs, I think.

However, if you want to make a new function that allows rendering/parsing nested data like that, you could send a pull request with new functions and types and if it looks good, it could be merged.