I'm pretty sure it's not possible to do this but I'm still asking for it.
Is there a way for a user to insert a null (or an undefined) value into an html text input?
I need to distinguish between a null value and an empty string and I would like to allow the user to set this value into a single input.
For what I can see across the web, the standard solution to this problem is to match the text input with a checkbox that tell if the value is null or not. From my understanding, the limitation is linked to the fact that the textbox can hold an empty string but not a null value so that's why I think it's not possible to do exactly what I want.
You can't tell a text input to have any kind of null value. Empty checkboxes have a value of an empty string '' by definition. The best way to do it, as you say, is to have a checkbox that toggles the disabled property of the text input, which gives a similar semantic.
Necromancing.
The accepted answer is kindof wrong - there is a way, sort of.
If you set the textbox state to disabled (for example with the chrome developer tools), then it won't submit the input box's value.
Hence, if you deserialize the form model from a post-request, the text's value will be NULL, unless your deserializer deliberately changes data.
Related
I have an edit page where several fields are conditionally disabled, based on the user's role. When the fields are disabled, their values are not posted to the server (as expected), which causes the ModelState to be invalid, as the values are required.
To get around this, I want to add Html.HiddenFor() for the fields; so that a value will still get posted (and so that it will retain those values if the View is returned). However, in the case that those fields are not disabled, I will then have both a TextBoxFor and a HiddenFor going to the same model property.
I have run a couple tests, and it appears that when this happens, the value of the first element on the form will be binded to the model, while the next one just gets ignored. If this is the case, then I should be able to just put the HiddenFor after the TextBoxFor, in which case the value of the hidden input will only be posted when the regular input is disabled.
#Html.TextBoxFor(m => m.FirstName)
#Html.HiddenFor(m => m.FirstName) #*Only gets binded to the model if the above text box is disabled*#
(There is some JavaScript that conditionally disabled the visible TextBox).
So two questions: 1) Is it documented that MVC binding will always work this way; can I safely have both of these fields?
And, 2) Is there a better approach to accomplishing this? I know that I can but the HiddenFor inside an #If statement so that it will only get created if the TextBox is disabled; but that is a lot of extra logic in the View that I'd like to avoid.
The DefaultModelBinder reads the values from the request in order and binds the first matching name/value pair and ignores subsequent matches (unless the property is IEnumerable). This is how the CheckBoxFor() method ensures a true or false value is always submitted to the controller (the method generates a checkbox with value="True" and a hidden input with value="False"), so you can safely add the hidden input after the textbox.
One option you might consider rather than a disabled textbox, is to make it readonly, which means it will always submit a value, therefore you only need one input (and you can always style it to look disabled if that is what you want).
Have a look at the following screenshot. You can see that the text input field is empty, yet its value attribute is set to "b".
You'll also notice in the Properties tab, under input, that value here is set to "". Why are they different? What does this mean?
Could this be related to the fact that the input was rendered by React?
If it helps, here is the jsx responsible for this element (redacted):
return (
<td
key={field._id}
className={`oldField ${colPos}`}
>
<input
type="text"
defaultValue={value}
onChange={this.changeOldField(record, field)}
/>
</td>
)
It seems that you are changing the defaultValue based on something from the state. The defaultValue prop should be set only once and not changed later on, because any more changes will be ignored by React. If you want to change the value based on state you should use the normal value prop. Otherwise, if you want a predefined value to appear to the user and at the same time control the input when it gets changed, you can either use some logic in your code that handles both onChange and the code in your component that wants to automatically change the value, or possibly place it in the placeholder prop, which will give you something like what you want.
I'm using standard HTML TextBoxFor helpers in an MVC5 project and wanted to set a textbox to accept numeric values only.
So I've set the type to be number.
#Html.TextBoxFor(model => model.PP_IMP_M1, "{0:0}", new { #type ="number"})
I'm not sure what the functionality of the HTML input type=number is supposed to be but when I type only letters in the textbox and tab out, the textbox clears itself as the value was not numeric. This is expected and correct.
However, if I type the first character as a number and follow this with random letters then the mixed text value remains in the textbox. I know the character 'e' may have been acceptable but I'm entering things like '12hgf' & '45dddd' and the textbox accepts the value after I tab out.
Is this the expected behaviour for an input with type set as number?
I was hoping the type=number would only accept numeric values without me having to use javascript or jquery.
Any help on this issue would be appreciated.
Shuja
I am using the djFilteringSelect control to show values in a dropdown as user type a value.
The lookup and typehead is working fine. The user type a letter and the dropdown allow the user to select a value which is then displayed in the dropdown field.
If the user now decide to remove the value first selected so that the combobox is empty and leave the field, then the first value in the list is now automatically filled in.
The consequence of this is that if the user have added a value there is no way to remove the value and leave the box emtpy.
I am using required=false for both the control and the dojo attribute but it does not seem to help. There are also a few other djFilteringSelect attributes I have tried like "Autocomplete" and "trim" but it does not work
Here is the code
<xe:djFilteringSelect id="test" type="select" store="jsondata" searchAttr="data" required="false" labelType="html" invalidMessage="Not valid">
<xe:this.dojoAttributes>
<xp:dojoAttribute name="required" value="false"></xp:dojoAttribute>
</xe:this.dojoAttributes>
</xe:djFilteringSelect>
Initally the field is not required, but if the user have entered a value it is required.
My question is if there a way to prevent the djFilteringSelect control to always populate the field if I have previously added a value
I found someone who solved this in another stack overflow topic, by creating an empty entry in my data store. but I could not get this to work
Dojo: Select of empty value for FilteringSelect while required=false
I do this quite a lot. Right now I don't have a working sample to show you (since I moved to bootstrap - and have to code the selects by manually adding select2 controls) but something like this should do it...
I add an "empty" value at the top of my select - and that seems to work no matter whether I am using a combobox, djCombobox or combobox with select2 from bootstrap. My markup typically looks like:
<xp:comboBox id="inputLocationSelector" value="#{User.catchListType}" disableClientSideValidation="true">
<xp:selectItem itemLabel="(none)" itemValue=""></xp:selectItem>
<xp:selectItems>
<xp:this.value><![CDATA[${Configuration.meta.listLocationTypeOptions}]]></xp:this.value>
</xp:selectItems>
</xp:comboBox>
Then you could specify "(none)", "All" or " " for the "not-selected" value depending on your needs.
Validation is a different thing so just specifying "required=false" does not give you the "empty" value.
/John
In my HTML markup I have an input of type text which has a two-way binding (using ng-model) to a decimal property. The object which contains this decimal property is fetched using a Breeze query on the client side. I can see that the Breeze query has successfully fetched the data and can see the initial value of the property (i.e. 1.25) in the text input. If I delete the decimal point and try to type it in again it will not allow me to do so and at this point I can only type in a number - effectively what I end up with is an integer value.
Can anyone tell me if Angular or Breeze is doing something behind the scenes that is limiting a text input to only being able to accept numbers instead of any text. I've inspected the input element in question in the browser to see if anything extra was "bolted on" that may have caused this but nothing jumps out. The "fix" or workaround would be change the input type to number and set the step attribute to "any" but nevertheless I would still like to understand the cause so any help will be greatly appreciated.
Thanks
I'm having the same issue and I think the problem is that due to the two-way binding the value is expected to be valid at any given moment. Apparently "1." is not a valid number so it doesn't like it. If you type "125" and then go back and insert the "." it will accept "1.25".
My current solution is to use debounced updates:
<input type="{{type}}" ng-model="ngModel" ng-model-options="{ updateOn: 'default blur', debounce: { default: 1000, blur: 0 } }">
If you do not want timeouts at all you could use just:
ng-model-options="{ updateOn: 'blur' }
More on this here: https://docs.angularjs.org/api/ng/directive/ngModelOptions
Depending on your localization settings, the numeric input field may accept only numbers and commas (not decimal points). As the validation is done on unser input, angular is able to set the value with the decimal point without failing.
By the way, why would you want to use breeze, when AngularJS has all you need to link your fields to the model?