JHipster: jhi-alert-error element and server side form validation?

问题

I am using JHipster 3.3. In the generated "entity"-dialog.html, I noticed the tag jhi-alert-error element will display server validation error so for example if a field is mandatory as specified in entity JPA class like

    @NotNull
    private String name;

Then error message for that field will be returned after clicking the Submit button if value of the field is empty.

So questions:

How is jhi-alert-error implemented? I can't seem to see its implementation
I tried tweaking JPA annotation to make a field unique BUT this time no error message will be displayed in jhi-alert-error if I break the unique constraint by adding 2 records having the same value for the field, E.g.

// note 'unique=true' below

@NotNull @Column(name = "name", unique=true)
private String name;

or

@Table(name="Module", uniqueConstraints = @UniqueConstraint(columnNames = "Name")) public Class Module implements Serializable { ...

So how would I go about implementing my own server side form validation so error messages will be displayed in jhi-alert-error when the unique constraint of a field is broken after clicking the Submit button?

Thanks in advance,

回答1:

I'm using a slightly older version of jhipster (2.26), so there could be some differences in the code. To answer your first question the jhi-alert-error is a custom Angular directive, have a look at the alert.directive.js file and the jhAlertError directive (should appear after the jhAlert directive). The directive expects the httpResponse.data object to be the ErrorDTO server side object.

To add custom error messages, you need to return an ErrorDTO object and the directive will display the message. To do this you need to throw an exception and ensure that the spring AOP - ExceptionTranslator is configured to catch it. If you don't want to create new custom Exceptions, you can use the CustomParameterizedException:

@RequestMapping(value = "/pizzas",
        method = RequestMethod.POST,
        produces = MediaType.APPLICATION_JSON_VALUE)
@Timed
public ResponseEntity<Pizza> create(@RequestBody Pizza pizza) throws URISyntaxException {
    if(pizza.isDisgusting()){
        throw new CustomParameterizedException("Sorry, your pizza recipe is horrible");
    }
    log.debug("REST request to save Pizza : {}", pizza);
    if (pizza.getId() != null) {
        return ResponseEntity.badRequest().header("Failure", "A new pizza cannot already have an ID").body(null);
    }
    Pizza result = pizzaRepository.save(pizza);
    return ResponseEntity.created(new URI("/api/pizzas/" + pizza.getId())).body(result);
}

来源：https://stackoverflow.com/questions/37727959/jhipster-jhi-alert-error-element-and-server-side-form-validation

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