sample.js

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';
import { tap } from 'rxjs/operators';
import { FormGroup } from '@angular/forms';

import { FormlyFieldConfig, FormlyFormOptions } from '@ngx-formly/core';
import { FormlyJsonschema } from '@ngx-formly/core/json-schema';


export interface IFormlyUser {
    type: string;
    form: FormGroup;
    fields: FormlyFieldConfig[];
    options: Object;
}


@Injectable({
    providedIn: 'root'
})
export class SchemaLoader {
    public type: string;


    constructor(
        private http: HttpClient,
        private formlyJsonschema: FormlyJsonschema,
    ) { };

    loadJsonSchema(type: string, instance: IFormlyUser) {
        this.http.get<any>(`assets/user/json-schema/${type}.json`).pipe(
            tap(({ schema }) => {
                instance.type = type;
                instance.form = new FormGroup({});
                instance.options = {};
                instance.fields = [this.formlyJsonschema.toFieldConfig(schema)].map(field => {
                    field.fieldGroup.map(fieldGroup => {
                        let property = schema.properties[fieldGroup.key];
                        if ('hide' in property) {
                            fieldGroup.hide = property.hide;
                        }
                        return fieldGroup;
                    });
                    return field;
                });
            }),
        ).subscribe();
    }

}