Responders don't use valid? to check for errors in models to figure out if the request was successful or not, and relies on your controllers to call save or create to trigger the validations.

Arguably, the rails-team's choice of raising ArgumentError instead of validation error is correct in the sense that we have full control over what options a user can select from a radio buttons group, or can select over a select field, so if a programmer happens to add a new radio button that has a typo for its value, then it is good to raise an error as it is an application error, and not a user error. However, for APIs, this will not work because we do not have any control anymore on what values get sent to the server.

When the controller creates the user, instead of adding a validation error to the record, it raises an exception. How to avoid this?

In case anyone wants a hack, here is what I came up with.

Validate Forms

This rule has a few exceptions: It’s helpful to validate inline as the user is typing when creating a password (to check whether the password meets complexity requirements), when creating a user name (to check whether a name is available) and when typing a message with a character limit.

Ideally, inline validation messages should appear around 500 to 1000 milliseconds after the user has stopped typing or after they’ve moved to the next field.

Due to our emotional distress measure having little prior validation, and our physical distress measure being entirely new, we first provide data to support the appropriateness of the two measures.

Negative values included when assessing air quality In computing average pollutant concentrations, EPA includes recorded values that are below zero. EPA advised that this is consistent with NEPM AAQ procedures. Logically, however, the lowest possible value for air pollutant concentrations is zero. Either it is present, even if in very small amounts, or it is not. Negative values are an artefact of the measurement and recording process. Leaving negative values in the data introduces a negative bias, which potentially under represents actual concentrations of pollutants. We noted a considerable number of negative values recorded. For example, in 2016, negative values comprised 5.3 per cent of recorded hourly PM2.5 values, and 1.3 per cent of hourly PM10 values. When we excluded negative values from the calculation of one‐day averages, there were five more exceedance days for PM2.5 and one more for PM10 during 2016.

we can generate cross-validated predictions of the test scores with precision comparable to the gold-standard test–retest reliabilities.

It is clear from the use of ES2 and RMG-II cell lines that the Atlas Antibodies ARID1A antibody is specific for ARID1A in both Western blots and formalin-fixed paraffin embedded preparations of human origin and, coupled with the literature evidence, that it is validated in human tissue.

A No Primary antibody control (NPA) showed no staining in the epithelial or nuclear compartment (Figure 3B; Dataset e).

There was no cytoplasmic or extracellular stromal background staining present and the antibody titrated successfully losing the intensity of staining, as expected

Control slides, omitting the primary antibody, were negative except for the ER2 condition in the RMG-II cell pellet where a weak cytoplasmic background could be seen (Figure 2; Dataset d). Thus there was minimal background inherent in the staining procedure. It was therefore determined that the antibody showed specificity for formalin-fixed paraffin embedded tissues and could be run on murine tissue.

Using Western blot and IHC on murine wild-type and knockout tissue we have demonstrated that this antibody to ARID1A correctly stains murine tissue by immunohistochemistry.