uk.ac.ed.epcc.webapp.model.data

Interface FieldConstraint

All Known Implementing Classes:

MultiFieldConstraint

public interface FieldConstraint

Interface for form constraints that restrict values of a field based on the values in other fields. These are designed to be implemented as multi-stage forms so the constrained fields are show after the dependencies.

Method Summary

Modifier and Type	Method and Description
static FieldConstraint	add(FieldConstraint a, FieldConstraint b) Merge two FieldConstraints values can be null
<I extends Input> Selector<I>	apply(boolean support_multi_stage, java.lang.String field, Selector<I> original, Form form, java.util.HashMap fixtures) Mutate a Selector based on other form fields.

Method Detail

apply

<I extends Input> Selector<I> apply(boolean support_multi_stage,
                                    java.lang.String field,
                                    Selector<I> original,
                                    Form form,
                                    java.util.HashMap fixtures)

Mutate a Selector based on other form fields. Normally this requires the value of the input to have a fixed value e.g. an UnmodifiableInput, a ListInput with a single valid option or a suppressed field. If the prerequisite fields are not fixed or not present then this method can return null to request an additional form stage be introduced. The form builder should then retry this field in subsequent stages (where previous fields will be locked). Fixed values are copied into the fixtures map. This also can contain values for supressed fields. Care needs to be taken with pre-requisites that are optional. Ideally if support_multi_stage is false the method should add a corresponding FormValidator to the form instead and return the original Selector

Type Parameters:

I - type of Input

Parameters:

support_multi_stage - Does surrounding context support multi-stage

field - Field that Selector is for

original - Selector

form - Form being built.

fixtures - HashMap of fixed field data. This can include supressed fields. note values of optional fields may be null.

Returns:

mutated Selector or null to request an additional form stage.

add

static FieldConstraint add(FieldConstraint a,
                           FieldConstraint b)

Merge two FieldConstraints values can be null

Parameters:

a -

b -

Returns: