self-assert / DraftAssistant

Class: abstract DraftAssistant<Model, ContainerModel>

Provides an assistant to guide the completion of a model.

A DraftAssistant encapsulates the logic needed to:

• track the current state of a form field or group of fields,
• validate the model being built,
• handle and route failed assertions,
• notify observers (viewers) of changes or validation failures.

Assistants can be nested and composed to build complex models.

Remarks

Originally, this class was named ModelCreator. Later, it was renamed to FormCompletionAssistant, employing the metaphor of an assistant guiding form completion. This could have led to confusion, since the class has more use cases than just form completion.

It can, for example, be used in a backend context to validate an object before persisting it.

Extended by

• FieldDraftAssistant
• SectionDraftAssistant

Type Parameters

Type Parameter	Default type	Description
Model	any	The type of the model the assistant helps to create.
ContainerModel	any	The type of the container model the assistant works on.

Model creation

isInvalidModel()

static isInvalidModel(potentialModel): boolean

Parameters

Parameter	Type
potentialModel	unknown

Returns

boolean

---

createModel()

abstract createModel(): Model

Attempts to create a model. It fails if any of the assertions fail.

Returns

Model

See

withCreatedModelDo.

Throws

RulesBroken if the model is invalid

---

withCreatedModelDo()

withCreatedModelDo<ReturnType>(validModelClosure, invalidModelClosure): ReturnType

Executes a closure depending on whether the model is valid or not after creating it.

Type Parameters

Type Parameter	Description
ReturnType	The type of the value returned by the closures.

Parameters

Parameter	Type	Description
validModelClosure	(model) => ReturnType	A closure that will be called with the created model if it's valid.
invalidModelClosure	() => ReturnType	A closure that will be called if the model is invalid.

Returns

ReturnType

The return value of the closure that was called.

---

getModel()

getModel(): Model

Returns

Model

---

setModel()

setModel(newModel): void

Parameters

Parameter	Type
newModel	Model

Returns

void

---

resetModel()

resetModel(): void

Resets the model to its initial value.

Returns

void

---

setModelFrom()

setModelFrom(containerModel): void

Sets the model from its container.

Parameters

Parameter	Type
containerModel	ContainerModel

Returns

void

Rules

addBrokenRule()

addBrokenRule(aBrokenRuleLabel): void

Adds a rule to the list of broken rules.

Parameters

Parameter	Type
aBrokenRuleLabel	LabeledRule

Returns

void

---

addBrokenRules()

addBrokenRules(brokenRules): void

Adds a list of rules to the list of broken rules.

Parameters

Parameter	Type
brokenRules	LabeledRule[]

Returns

void

---

hasBrokenRules()

hasBrokenRules(): boolean

Returns

boolean

true if the list of broken rules is not empty

---

doesNotHaveBrokenRules()

doesNotHaveBrokenRules(): boolean

Opposite of hasBrokenRules.

Returns

boolean

---

brokenRulesDescriptions()

brokenRulesDescriptions(): string[]

Returns

string[]

The descriptions of the broken rules

---

handles()

handles(aRule): boolean

Parameters

Parameter	Type
aRule	LabeledRule

Returns

boolean

true if this assistant handles the given Assertion.

---

addLabelId()

addLabelId(aLabelId): void

Adds an assertion id to the list of handled assertions.

Parameters

Parameter	Type
aLabelId	string

Returns

void

---

hasBrokenRule()

hasBrokenRule(aBrokenRuleLabel): boolean

Parameters

Parameter	Type
aBrokenRuleLabel	LabeledRule

Returns

boolean

---

hasOnlyOneRuleBrokenIdentifiedAs()

hasOnlyOneRuleBrokenIdentifiedAs(assertionId): boolean

Parameters

Parameter	Type
assertionId	string

Returns

boolean

true if this assistant has only one failed assertion that is identified as the given assertionId.

Remarks

Used mostly for testing.

---

removeBrokenRules()

removeBrokenRules(): void

Returns

void

Viewers

accept()

accept(aViewer): void

Adds a viewer to the list of observers.

Parameters

Parameter	Type
aViewer	DraftViewer<Model>

Returns

void

---

removeViewer()

removeViewer(aViewer): void

Removes a viewer from the list of observers.

Parameters

Parameter	Type
aViewer	DraftViewer<never>

Returns

void

---

numberOfViewers()

numberOfViewers(): number

Returns

number

The number of viewers currently observing the assistant.

Others

topLevelModelFromContainer()

static topLevelModelFromContainer<Model>(): ModelFromContainer<Model, unknown>

Type Parameters

Type Parameter	Default type
Model	any

Returns

ModelFromContainer<Model, unknown>

A default model getter from a container for the top-level assistant. Since there is no container to get the model from, it throws an error.