QuestionFormGeneratorService.ts

export class QuestionFormGeneratorService {

    constructor() {}
    getQuestionsFormGroup(quesitons: Question[]): FormGroup {
        const group: {
            [key: string]: AbstractControl
        } = {};
        quesitons.forEach(question => {
            const validatiors = this.getValidationFunctions(question.validationRules);
            group[question.externalQuestionId] = question.answerType.toUpperCase() === selectMulti ? new FormGroup(this.getAnswerOptionsControlsObj(question.answerOptions), validatiors) : new FormControl(question.answer || '', validatiors);
        });
        return new FormGroup(group);
    }
    private getAnswerOptionsControlsObj(answerOptions: AnswerOption[]) {
        const group: {
            [key: string]: AbstractControl
        } = {};
        answerOptions.forEach(answerOption => group[answerOption.optionCode] = new FormControl());
        return group;
    }
    private getValidationFunctions(validationRuleStrings: string[]): Array < (control: AbstractControl) => ValidationErrors | null > | null {
        const validationRules = [];
        for (const validationRuleStr of validationRuleStrings) {
            const validationRule = ValidationRule.validationRulesMap.get(validationRuleStr.toUpperCase());
            if (validationRule !== undefined) {
                validationRules.push(validationRule.validationFn);
            }
        }
        return validationRules.length > 0 ? validationRules : null;
    }
}