[elm-discuss] Re: Forms with Floats / Dates

[Vlad GURDIGA]

Hi Simon!

As a newcomer to Elm, I too have this issue fresh in my experience, and my 
approach 

 has 
been similar to what Witold Szczerba’s: I’ve built myself a MyDate type to 
hold all the information I need, and a few helper functions that work with 
values of that type:

type alias MyDate =
{ string : String
, date : Maybe Date
, validationMessage : String
}

I think the essence of the approach is to hold user’s input separate from 
the value that we want to make out of it in the end. 邏


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[elm-discuss] Re: Forms with Floats / Dates

[Ray Toal]

Has there been any consensus on this question. I would _love_ to know if 
there is a preferred Elm style for this. It seems like a very big deal.

Here's what I can glean from the thread so far. (I hope this post 
reactivates the discussion.)

1. Floats and Dates and other such things are commonly taken from user 
input in text fields.
2. There is a very valid question as to what is the proper MODEL should 
the model hold a Float or a String?
3. There is some commentary in this thread about just using onChange 
instead of onInput. Personally I think this is a non-question. Of course we 
should be using onInput for almost everything. Live programming is 
important and becoming expected. Unless you are hitting a server on every 
keypress of COURSE you should aim for the live UX. Even then, you should 
debounce whenever possible.
4. input type=number is a possibility but has some quirks.
5. So we are back to question #2.

If we use String for the Model type, the code feels shorter but the whole 
thing feels hacky.

If we use Float for the Model type there is a lot of processing of Result 
String String types everywhere. Even Result.andThen doesn't help the 
readability much.

What have people been using? Have you been making your models Floats or 
Strings?




On Saturday, January 21, 2017 at 7:08:04 AM UTC-8, Simon wrote:
>
> I think it is not uncommon to collect dates and float values from users.
>
> update ...
> NewValue v -> 
> { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 }
>
> floatInput : Float -> Html Msg 
> floatInput v =
> input 
> [ onInput NewValue 
> , value (toString v) 
> ] []
>
> The problem with the above is that the moment you type the . toFloat 
> fails and you get a 0 in your model. One way around it could be to delay 
> processing of the value by using onBlur (below), but I was wondering how 
> others handled this.
>
> floatInput_ : Float -> Html Msg 
> floatInput_ v =
> input 
> [ onBlur NewValue 
> , value (toString v) 
> ] []
>
> ​
>

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[elm-discuss] Re: Forms with Floats / Dates [DOM diffing issue]

[Simon]

That’s the way the virtual dom works, the view is rewritten on every loop

To be honest, I thought the exact opposite was the case - only bits that 
have changed are rewritten?

Meanwhile defaultValue a perfect solution

@Witold: I can see how your solution works in some cases where you have 
complete control of the model. But I have a recursive datastructure and 
can’t readily start adding extra fields into leaf values of my tree

Simon 

On Sunday, 22 January 2017 13:55:38 UTC+1, Bernardo wrote:

That's the way the virtual dom works, the view is rewritten on every loop. 
> You need to change line 49 to HA.defaultValue (toString model). 
>
> On Sunday, 22 January 2017 06:28:43 UTC-3, Simon wrote:
>>
>> Here is an example of the problem 
>> https://runelm.io/c/5nk
>>
>>
>>
>> On Sunday, 22 January 2017 10:22:34 UTC+1, Simon wrote:
>>>
>>> So my problem has evolved. I can see that onChange would work, but I am 
>>> also subscribing to KeyBoard.presses. As a result every keypress is 
>>> firing the update function even while onChange is waiting for a blur. 
>>>
>>> That shouldn’t be an issue I thought. If the key press does not change 
>>> the part of the model with the float in, then that part of the DOM would 
>>> not be rewritten, and indeed will remain constant until the ‘change’ event. 
>>> But that’s not the case. Even when I direct every keypress to NoOp (causing 
>>> update to return the model unchanged) the DOM is being rewritten and I’m 
>>> losing the edits in the input field.
>>>
>>> I believe a possible fix it to use Html.Keyed but, before I try that, 
>>> I’m wondering why the DOM is being rewritten and whether there are other 
>>> approaches I could take
>>>
>>> On Sunday, 22 January 2017 09:36:19 UTC+1, Simon wrote:
>>>
>>> Hi, 
 your idea looked interesting until I tried it. https://runelm.io/c/y3g 
  
 Try entering a number and then backspacing to delete it. I could not 
 get rid of the first digit


 I thought onChange would do it, but my early tests seem to suggest that 
 it is firing just as often as onInput, which defeats the object


 On Sunday, 22 January 2017 02:11:56 UTC+1, j weir wrote:
>
> Even simpler is to just use input [] [type_ "number"]  any reasons not 
> to?
>
> http://caniuse.com/#feat=input-number
>
> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>
> On Saturday, January 21, 2017 at 1:37:16 PM UTC-8, j weir wrote:
>>
>> You could also format the input so it is always a decimal.
>>
>> And instead of using Result.withDefault 0.0, revert to the existing 
>> value.
>> This way the input won't be destroyed if the user fat fingers a non 
>> numeral.
>>
>> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>>
>>
>>
>> On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak 
>> wrote:
>>>
>>> I'd consider storing the whole string in the model and passing it to 
>>> value. This way you can capture whatever input the user types and 
>>> convert it to float only when you actually need to do something with 
>>> the 
>>> float.
>>>
>>> IMHO because the input tag allows you to type any kind of string, 
>>> you should treat the value that comes from its onBlur as a string. 
>>> You could set type_ to "number", but that would still not exclude 
>>> some invalid inputs from being provided.
>>>
>>> On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:

 I think it is not uncommon to collect dates and float values from 
 users.

 update ...
 NewValue v -> 
 { model | floatvalue = String.toFloat v |> Result.withDefault 
 0.0 }

 floatInput : Float -> Html Msg 
 floatInput v =
 input 
 [ onInput NewValue 
 , value (toString v) 
 ] []

 The problem with the above is that the moment you type the . 
 toFloat fails and you get a 0 in your model. One way around it 
 could be to delay processing of the value by using onBlur (below), but 
 I 
 was wondering how others handled this.

 floatInput_ : Float -> Html Msg 
 floatInput_ v =
 input 
 [ onBlur NewValue 
 , value (toString v) 
 ] []

 ​

>>> ​
>>>
>> ​

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Re: [elm-discuss] Re: Forms with Floats / Dates

[Witold Szczerba]

Hi,
this is my humble solution to this problem: https://runelm.io/c/a7u

In my application, I did not have to deal with numbers in forms, but I was
using "form" types like this:
type alias TextField = { value: String, error: String }
The validation was performed on update and form error messages was looking
for error not equal to empty string.

So, the idea with number fields:
type alias FloatField = { input: String, value: Maybe Float }
is like a variation of that one (you could add error here as well).

Regards,
Witold Szczerba

On Sun, Jan 22, 2017 at 9:36 AM, Simon  wrote:

> Hi,
> your idea looked interesting until I tried it. https://runelm.io/c/y3g
> Try entering a number and then backspacing to delete it. I could not get
> rid of the first digit
>
>
> I thought onChange would do it, but my early tests seem to suggest that it
> is firing just as often as onInput, which defeats the object
>
>
> On Sunday, 22 January 2017 02:11:56 UTC+1, j weir wrote:
>>
>> Even simpler is to just use input [] [type_ "number"]  any reasons not to?
>>
>> http://caniuse.com/#feat=input-number
>>
>> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>>
>> On Saturday, January 21, 2017 at 1:37:16 PM UTC-8, j weir wrote:
>>>
>>> You could also format the input so it is always a decimal.
>>>
>>> And instead of using Result.withDefault 0.0, revert to the existing
>>> value.
>>> This way the input won't be destroyed if the user fat fingers a non
>>> numeral.
>>>
>>> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>>>
>>>
>>>
>>> On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak wrote:

 I'd consider storing the whole string in the model and passing it to
 value. This way you can capture whatever input the user types and
 convert it to float only when you actually need to do something with the
 float.

 IMHO because the input tag allows you to type any kind of string, you
 should treat the value that comes from its onBlur as a string. You
 could set type_ to "number", but that would still not exclude some
 invalid inputs from being provided.

 On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:
>
> I think it is not uncommon to collect dates and float values from
> users.
>
> update ...
> NewValue v ->
> { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 
> }
>
> floatInput : Float -> Html Msg
> floatInput v =
> input
> [ onInput NewValue
> , value (toString v)
> ] []
>
> The problem with the above is that the moment you type the . toFloat
> fails and you get a 0 in your model. One way around it could be to
> delay processing of the value by using onBlur (below), but I was wondering
> how others handled this.
>
> floatInput_ : Float -> Html Msg
> floatInput_ v =
> input
> [ onBlur NewValue
> , value (toString v)
> ] []
>
> ​
>
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[elm-discuss] Re: Forms with Floats / Dates [DOM diffing issue]

[Bernardo]

That's the way the virtual dom works, the view is rewritten on every loop. 
You need to change line 49 to HA.defaultValue (toString model). 

On Sunday, 22 January 2017 06:28:43 UTC-3, Simon wrote:
>
> Here is an example of the problem 
> https://runelm.io/c/5nk
>
>
>
> On Sunday, 22 January 2017 10:22:34 UTC+1, Simon wrote:
>>
>> So my problem has evolved. I can see that onChange would work, but I am 
>> also subscribing to KeyBoard.presses. As a result every keypress is 
>> firing the update function even while onChange is waiting for a blur. 
>>
>> That shouldn’t be an issue I thought. If the key press does not change 
>> the part of the model with the float in, then that part of the DOM would 
>> not be rewritten, and indeed will remain constant until the ‘change’ event. 
>> But that’s not the case. Even when I direct every keypress to NoOp (causing 
>> update to return the model unchanged) the DOM is being rewritten and I’m 
>> losing the edits in the input field.
>>
>> I believe a possible fix it to use Html.Keyed but, before I try that, I’m 
>> wondering why the DOM is being rewritten and whether there are other 
>> approaches I could take
>>
>> On Sunday, 22 January 2017 09:36:19 UTC+1, Simon wrote:
>>
>> Hi, 
>>> your idea looked interesting until I tried it. https://runelm.io/c/y3g  
>>> Try entering a number and then backspacing to delete it. I could not get 
>>> rid of the first digit
>>>
>>>
>>> I thought onChange would do it, but my early tests seem to suggest that 
>>> it is firing just as often as onInput, which defeats the object
>>>
>>>
>>> On Sunday, 22 January 2017 02:11:56 UTC+1, j weir wrote:

 Even simpler is to just use input [] [type_ "number"]  any reasons not 
 to?

 http://caniuse.com/#feat=input-number

 https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164

 On Saturday, January 21, 2017 at 1:37:16 PM UTC-8, j weir wrote:
>
> You could also format the input so it is always a decimal.
>
> And instead of using Result.withDefault 0.0, revert to the existing 
> value.
> This way the input won't be destroyed if the user fat fingers a non 
> numeral.
>
> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>
>
>
> On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak wrote:
>>
>> I'd consider storing the whole string in the model and passing it to 
>> value. This way you can capture whatever input the user types and 
>> convert it to float only when you actually need to do something with the 
>> float.
>>
>> IMHO because the input tag allows you to type any kind of string, you 
>> should treat the value that comes from its onBlur as a string. You 
>> could set type_ to "number", but that would still not exclude some 
>> invalid inputs from being provided.
>>
>> On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:
>>>
>>> I think it is not uncommon to collect dates and float values from 
>>> users.
>>>
>>> update ...
>>> NewValue v -> 
>>> { model | floatvalue = String.toFloat v |> Result.withDefault 
>>> 0.0 }
>>>
>>> floatInput : Float -> Html Msg 
>>> floatInput v =
>>> input 
>>> [ onInput NewValue 
>>> , value (toString v) 
>>> ] []
>>>
>>> The problem with the above is that the moment you type the . 
>>> toFloat fails and you get a 0 in your model. One way around it 
>>> could be to delay processing of the value by using onBlur (below), but 
>>> I 
>>> was wondering how others handled this.
>>>
>>> floatInput_ : Float -> Html Msg 
>>> floatInput_ v =
>>> input 
>>> [ onBlur NewValue 
>>> , value (toString v) 
>>> ] []
>>>
>>> ​
>>>
>> ​
>>
>

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[elm-discuss] Re: Forms with Floats / Dates [DOM diffing issue]

[Simon]

Here is an example of the problem 
https://runelm.io/c/5nk



On Sunday, 22 January 2017 10:22:34 UTC+1, Simon wrote:
>
> So my problem has evolved. I can see that onChange would work, but I am 
> also subscribing to KeyBoard.presses. As a result every keypress is 
> firing the update function even while onChange is waiting for a blur. 
>
> That shouldn’t be an issue I thought. If the key press does not change the 
> part of the model with the float in, then that part of the DOM would not be 
> rewritten, and indeed will remain constant until the ‘change’ event. But 
> that’s not the case. Even when I direct every keypress to NoOp (causing 
> update to return the model unchanged) the DOM is being rewritten and I’m 
> losing the edits in the input field.
>
> I believe a possible fix it to use Html.Keyed but, before I try that, I’m 
> wondering why the DOM is being rewritten and whether there are other 
> approaches I could take
>
> On Sunday, 22 January 2017 09:36:19 UTC+1, Simon wrote:
>
> Hi, 
>> your idea looked interesting until I tried it. https://runelm.io/c/y3g  
>> Try entering a number and then backspacing to delete it. I could not get 
>> rid of the first digit
>>
>>
>> I thought onChange would do it, but my early tests seem to suggest that 
>> it is firing just as often as onInput, which defeats the object
>>
>>
>> On Sunday, 22 January 2017 02:11:56 UTC+1, j weir wrote:
>>>
>>> Even simpler is to just use input [] [type_ "number"]  any reasons not 
>>> to?
>>>
>>> http://caniuse.com/#feat=input-number
>>>
>>> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>>>
>>> On Saturday, January 21, 2017 at 1:37:16 PM UTC-8, j weir wrote:

 You could also format the input so it is always a decimal.

 And instead of using Result.withDefault 0.0, revert to the existing 
 value.
 This way the input won't be destroyed if the user fat fingers a non 
 numeral.

 https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164



 On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak wrote:
>
> I'd consider storing the whole string in the model and passing it to 
> value. This way you can capture whatever input the user types and 
> convert it to float only when you actually need to do something with the 
> float.
>
> IMHO because the input tag allows you to type any kind of string, you 
> should treat the value that comes from its onBlur as a string. You 
> could set type_ to "number", but that would still not exclude some 
> invalid inputs from being provided.
>
> On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:
>>
>> I think it is not uncommon to collect dates and float values from 
>> users.
>>
>> update ...
>> NewValue v -> 
>> { model | floatvalue = String.toFloat v |> Result.withDefault 
>> 0.0 }
>>
>> floatInput : Float -> Html Msg 
>> floatInput v =
>> input 
>> [ onInput NewValue 
>> , value (toString v) 
>> ] []
>>
>> The problem with the above is that the moment you type the . toFloat 
>> fails and you get a 0 in your model. One way around it could be to 
>> delay processing of the value by using onBlur (below), but I was 
>> wondering 
>> how others handled this.
>>
>> floatInput_ : Float -> Html Msg 
>> floatInput_ v =
>> input 
>> [ onBlur NewValue 
>> , value (toString v) 
>> ] []
>>
>> ​
>>
> ​
>

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[elm-discuss] Re: Forms with Floats / Dates [DOM diffing issue]

[Simon]

So my problem has evolved. I can see that onChange would work, but I am 
also subscribing to KeyBoard.presses. As a result every keypress is firing 
the update function even while onChange is waiting for a blur. 

That shouldn’t be an issue I thought. If the key press does not change the 
part of the model with the float in, then that part of the DOM would not be 
rewritten, and indeed will remain constant until the ‘change’ event. But 
that’s not the case. Even when I direct every keypress to NoOp (causing 
update to return the model unchanged) the DOM is being rewritten and I’m 
losing the edits in the input field.

I believe a possible fix it to use Html.Keyed but, before I try that, I’m 
wondering why the DOM is being rewritten and whether there are other 
approaches I could take

On Sunday, 22 January 2017 09:36:19 UTC+1, Simon wrote:

Hi, 
> your idea looked interesting until I tried it. https://runelm.io/c/y3g  
> Try entering a number and then backspacing to delete it. I could not get 
> rid of the first digit
>
>
> I thought onChange would do it, but my early tests seem to suggest that it 
> is firing just as often as onInput, which defeats the object
>
>
> On Sunday, 22 January 2017 02:11:56 UTC+1, j weir wrote:
>>
>> Even simpler is to just use input [] [type_ "number"]  any reasons not to?
>>
>> http://caniuse.com/#feat=input-number
>>
>> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>>
>> On Saturday, January 21, 2017 at 1:37:16 PM UTC-8, j weir wrote:
>>>
>>> You could also format the input so it is always a decimal.
>>>
>>> And instead of using Result.withDefault 0.0, revert to the existing 
>>> value.
>>> This way the input won't be destroyed if the user fat fingers a non 
>>> numeral.
>>>
>>> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>>>
>>>
>>>
>>> On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak wrote:

 I'd consider storing the whole string in the model and passing it to 
 value. This way you can capture whatever input the user types and 
 convert it to float only when you actually need to do something with the 
 float.

 IMHO because the input tag allows you to type any kind of string, you 
 should treat the value that comes from its onBlur as a string. You 
 could set type_ to "number", but that would still not exclude some 
 invalid inputs from being provided.

 On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:
>
> I think it is not uncommon to collect dates and float values from 
> users.
>
> update ...
> NewValue v -> 
> { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 
> }
>
> floatInput : Float -> Html Msg 
> floatInput v =
> input 
> [ onInput NewValue 
> , value (toString v) 
> ] []
>
> The problem with the above is that the moment you type the . toFloat 
> fails and you get a 0 in your model. One way around it could be to 
> delay processing of the value by using onBlur (below), but I was 
> wondering 
> how others handled this.
>
> floatInput_ : Float -> Html Msg 
> floatInput_ v =
> input 
> [ onBlur NewValue 
> , value (toString v) 
> ] []
>
> ​
>
 ​

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[elm-discuss] Re: Forms with Floats / Dates

[Simon]

Hi, 
your idea looked interesting until I tried it. https://runelm.io/c/y3g  
Try entering a number and then backspacing to delete it. I could not get 
rid of the first digit


I thought onChange would do it, but my early tests seem to suggest that it 
is firing just as often as onInput, which defeats the object


On Sunday, 22 January 2017 02:11:56 UTC+1, j weir wrote:
>
> Even simpler is to just use input [] [type_ "number"]  any reasons not to?
>
> http://caniuse.com/#feat=input-number
>
> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>
> On Saturday, January 21, 2017 at 1:37:16 PM UTC-8, j weir wrote:
>>
>> You could also format the input so it is always a decimal.
>>
>> And instead of using Result.withDefault 0.0, revert to the existing value.
>> This way the input won't be destroyed if the user fat fingers a non 
>> numeral.
>>
>> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>>
>>
>>
>> On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak wrote:
>>>
>>> I'd consider storing the whole string in the model and passing it to 
>>> value. This way you can capture whatever input the user types and 
>>> convert it to float only when you actually need to do something with the 
>>> float.
>>>
>>> IMHO because the input tag allows you to type any kind of string, you 
>>> should treat the value that comes from its onBlur as a string. You 
>>> could set type_ to "number", but that would still not exclude some 
>>> invalid inputs from being provided.
>>>
>>> On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:

 I think it is not uncommon to collect dates and float values from users.

 update ...
 NewValue v -> 
 { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 }

 floatInput : Float -> Html Msg 
 floatInput v =
 input 
 [ onInput NewValue 
 , value (toString v) 
 ] []

 The problem with the above is that the moment you type the . toFloat 
 fails and you get a 0 in your model. One way around it could be to 
 delay processing of the value by using onBlur (below), but I was wondering 
 how others handled this.

 floatInput_ : Float -> Html Msg 
 floatInput_ v =
 input 
 [ onBlur NewValue 
 , value (toString v) 
 ] []

 ​

>>>

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[elm-discuss] Re: Forms with Floats / Dates

[Bernardo]

This is an improvement, but again, trying to validate on every key press 
causes problems. Type a number and you can't delete it with backspace, you 
can't enter a negative number, ctrl-z acts weird. Now, I'm sure you can 
work around all of these problems, but why don't wait until the user has 
finished and then update the model and validate?

On Saturday, 21 January 2017 22:11:56 UTC-3, j weir wrote:
>
> Even simpler is to just use input [] [type_ "number"]  any reasons not to?
>
> http://caniuse.com/#feat=input-number
>
> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>
> On Saturday, January 21, 2017 at 1:37:16 PM UTC-8, j weir wrote:
>>
>> You could also format the input so it is always a decimal.
>>
>> And instead of using Result.withDefault 0.0, revert to the existing value.
>> This way the input won't be destroyed if the user fat fingers a non 
>> numeral.
>>
>> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>>
>>
>>
>> On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak wrote:
>>>
>>> I'd consider storing the whole string in the model and passing it to 
>>> value. This way you can capture whatever input the user types and 
>>> convert it to float only when you actually need to do something with the 
>>> float.
>>>
>>> IMHO because the input tag allows you to type any kind of string, you 
>>> should treat the value that comes from its onBlur as a string. You 
>>> could set type_ to "number", but that would still not exclude some 
>>> invalid inputs from being provided.
>>>
>>> On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:

 I think it is not uncommon to collect dates and float values from users.

 update ...
 NewValue v -> 
 { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 }

 floatInput : Float -> Html Msg 
 floatInput v =
 input 
 [ onInput NewValue 
 , value (toString v) 
 ] []

 The problem with the above is that the moment you type the . toFloat 
 fails and you get a 0 in your model. One way around it could be to 
 delay processing of the value by using onBlur (below), but I was wondering 
 how others handled this.

 floatInput_ : Float -> Html Msg 
 floatInput_ v =
 input 
 [ onBlur NewValue 
 , value (toString v) 
 ] []

 ​

>>>

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[elm-discuss] Re: Forms with Floats / Dates

[j weir]

Even simpler is to just use input [] [type_ "number"]  any reasons not to?

http://caniuse.com/#feat=input-number

https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164

On Saturday, January 21, 2017 at 1:37:16 PM UTC-8, j weir wrote:
>
> You could also format the input so it is always a decimal.
>
> And instead of using Result.withDefault 0.0, revert to the existing value.
> This way the input won't be destroyed if the user fat fingers a non 
> numeral.
>
> https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164
>
>
>
> On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak wrote:
>>
>> I'd consider storing the whole string in the model and passing it to 
>> value. This way you can capture whatever input the user types and 
>> convert it to float only when you actually need to do something with the 
>> float.
>>
>> IMHO because the input tag allows you to type any kind of string, you 
>> should treat the value that comes from its onBlur as a string. You could 
>> set type_ to "number", but that would still not exclude some invalid 
>> inputs from being provided.
>>
>> On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:
>>>
>>> I think it is not uncommon to collect dates and float values from users.
>>>
>>> update ...
>>> NewValue v -> 
>>> { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 }
>>>
>>> floatInput : Float -> Html Msg 
>>> floatInput v =
>>> input 
>>> [ onInput NewValue 
>>> , value (toString v) 
>>> ] []
>>>
>>> The problem with the above is that the moment you type the . toFloat 
>>> fails and you get a 0 in your model. One way around it could be to 
>>> delay processing of the value by using onBlur (below), but I was wondering 
>>> how others handled this.
>>>
>>> floatInput_ : Float -> Html Msg 
>>> floatInput_ v =
>>> input 
>>> [ onBlur NewValue 
>>> , value (toString v) 
>>> ] []
>>>
>>> ​
>>>
>>

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[elm-discuss] Re: Forms with Floats / Dates

[j weir]

You could also format the input so it is always a decimal.

And instead of using Result.withDefault 0.0, revert to the existing value.
This way the input won't be destroyed if the user fat fingers a non numeral.

https://gist.github.com/jweir/9e8412a4fa0132866977626e337cb164



On Saturday, January 21, 2017 at 9:11:41 AM UTC-8, Rafał Cieślak wrote:
>
> I'd consider storing the whole string in the model and passing it to value. 
> This way you can capture whatever input the user types and convert it to 
> float only when you actually need to do something with the float.
>
> IMHO because the input tag allows you to type any kind of string, you 
> should treat the value that comes from its onBlur as a string. You could 
> set type_ to "number", but that would still not exclude some invalid 
> inputs from being provided.
>
> On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:
>>
>> I think it is not uncommon to collect dates and float values from users.
>>
>> update ...
>> NewValue v -> 
>> { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 }
>>
>> floatInput : Float -> Html Msg 
>> floatInput v =
>> input 
>> [ onInput NewValue 
>> , value (toString v) 
>> ] []
>>
>> The problem with the above is that the moment you type the . toFloat 
>> fails and you get a 0 in your model. One way around it could be to delay 
>> processing of the value by using onBlur (below), but I was wondering how 
>> others handled this.
>>
>> floatInput_ : Float -> Html Msg 
>> floatInput_ v =
>> input 
>> [ onBlur NewValue 
>> , value (toString v) 
>> ] []
>>
>> ​
>>
>

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[elm-discuss] Re: Forms with Floats / Dates

[Rafał Cieślak]

I'd consider storing the whole string in the model and passing it to value. 
This way you can capture whatever input the user types and convert it to 
float only when you actually need to do something with the float.

IMHO because the input tag allows you to type any kind of string, you 
should treat the value that comes from its onBlur as a string. You could 
set type_ to "number", but that would still not exclude some invalid inputs 
from being provided.

On Saturday, January 21, 2017 at 4:08:04 PM UTC+1, Simon wrote:
>
> I think it is not uncommon to collect dates and float values from users.
>
> update ...
> NewValue v -> 
> { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 }
>
> floatInput : Float -> Html Msg 
> floatInput v =
> input 
> [ onInput NewValue 
> , value (toString v) 
> ] []
>
> The problem with the above is that the moment you type the . toFloat 
> fails and you get a 0 in your model. One way around it could be to delay 
> processing of the value by using onBlur (below), but I was wondering how 
> others handled this.
>
> floatInput_ : Float -> Html Msg 
> floatInput_ v =
> input 
> [ onBlur NewValue 
> , value (toString v) 
> ] []
>
> ​
>

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[elm-discuss] Re: Forms with Floats / Dates

[Bernardo]

Instead of onInput I listen to the *change *event so I don't validate and 
update the model on every key press. In most cases I don't see a reason to 
update the model on every key press.

On Saturday, 21 January 2017 12:16:03 UTC-3, Simon wrote:
>
> Correction 
>
> toString (toFloat "5.") == "5"-i.e. the `.` gets stripped off so you 
> can never actually add decimal values
>
>
>
> On Saturday, 21 January 2017 16:08:04 UTC+1, Simon wrote:
>>
>> I think it is not uncommon to collect dates and float values from users.
>>
>> update ...
>> NewValue v -> 
>> { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 }
>>
>> floatInput : Float -> Html Msg 
>> floatInput v =
>> input 
>> [ onInput NewValue 
>> , value (toString v) 
>> ] []
>>
>> The problem with the above is that the moment you type the . toFloat 
>> fails and you get a 0 in your model. One way around it could be to delay 
>> processing of the value by using onBlur (below), but I was wondering how 
>> others handled this.
>>
>> floatInput_ : Float -> Html Msg 
>> floatInput_ v =
>> input 
>> [ onBlur NewValue 
>> , value (toString v) 
>> ] []
>>
>> ​
>>
>

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[elm-discuss] Re: Forms with Floats / Dates

[Simon]

Correction 

toString (toFloat "5.") == "5"-i.e. the `.` gets stripped off so you 
can never actually add decimal values



On Saturday, 21 January 2017 16:08:04 UTC+1, Simon wrote:
>
> I think it is not uncommon to collect dates and float values from users.
>
> update ...
> NewValue v -> 
> { model | floatvalue = String.toFloat v |> Result.withDefault 0.0 }
>
> floatInput : Float -> Html Msg 
> floatInput v =
> input 
> [ onInput NewValue 
> , value (toString v) 
> ] []
>
> The problem with the above is that the moment you type the . toFloat 
> fails and you get a 0 in your model. One way around it could be to delay 
> processing of the value by using onBlur (below), but I was wondering how 
> others handled this.
>
> floatInput_ : Float -> Html Msg 
> floatInput_ v =
> input 
> [ onBlur NewValue 
> , value (toString v) 
> ] []
>
> ​
>

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