knockout-contrib | : metal : KnockoutJS Goodies Monorepo | Single Page Application library

After looking deep in the code, I found the issue. The paragraph including the error message should NOT be

Instead it should be

In essence, you need to use validationText instead of validationMessage. I had not found this anywhere in the documentation. Hopefully this helps someone.

I've looked at the source code of knockout validation (here) and it's pretty clear that two independent async validators are not supported.

The isValidating property is set to true as soon as an async rule is begins to run and set to false again as soon as that rule finishes. Therefore, multiple async rules clash.

There is only one solution. Remove the second async validator.

You can collapse the two checks into one either on the client side or on the server side.

To do it on the client side, you would need to write a validator that runs two Ajax requests and invokes the validation callback only after both of them have returned.

To do it on the server side, you would have to run the "is reachable" and "is in DB" checks in succession before giving an overall response to the client.

Personally I would prefer changing the server side, because

1. it keeps the client code tidy and manageable
2. it saves one HTTP round-trip per check
3. semantically, the URL check is one thing that fail for more than one reason
4. it's easy to let the server send a custom validation result and -message

Besides plain true or false, the validation plugin understands responses in this format:

Found a solution,

Most likely an issue with the type definitions which does not have an indexer to add custom validations. You can augment the KnockoutValidationRuleDefinitions interface temporarily in your code:

You could create a computed that returns the max amount depending on the selected frequency and then use that.