关于Polymer 1.0，使用iron-ajax制作数据服务器的问题

Question

I have a project using Polymer 1.2, and am trying to create a data server component using iron-ajax called review_data_service.html , which can make AJAX call to send (GET,POST,PUT or DELETE) request to backend like this:

<dom-module id="review-data-service">
        <template>
                <iron-ajax url= "[[URI]]"
                id="GET_REVIEWS"
                handle-as="json" 
                loading="{{loading}}" 
                on-response="handleResponse"
                content-type="application/json"
                auto></iron-ajax>
        </template>
        <script>
            Polymer({
                is: 'review-data-service',
                properties: {
                    reviewId : Number,
                    API: {
                        type: Object,
                        value:  () => {
                            return {
                                BASE : 'http://localhost:3000',
                                RESOURCE : 'reviews'
                            };
                        }
                    },
                    URI : {
                        type : String,
                        computed : 'setURI(API.BASE, API.RESOURCE)'
                    }
                },
                setURI : (BASE, RESOURCE) => {
                    return `${BASE}/${RESOURCE}`;
                },
                handleResponse : function (event) {
                    let promise = new Promise ((resolve, reject) => {
                        if (event.detail.response != null) {
                            resolve(event.detail.response);
                        } else {
                            reject('error');
                        }
                    });
                    promise.then(result => {
                        this.fire('getReviews', 
                            {reviews : result}
                        )
                    }, result => {
                        console.log('reject', result);
                    })
                }
            });
        </script>
    </dom-module>

In my another component, my-project-reviewer.html , I can get the review data successfully like this:

 listeners: {
                    'getReviews': '_getReviews',
            },

_getReviews: (event) => {
                this.reviews = event.detail.reviews;
                // can get the data successfully at here:
                console.log(this.reviews);
            },

However, when I try to show those data in the dom, it won't work:

<!-- cannot see anything here:  -->
                <template is="dom-repeat" items="[[reviews]]">
                        <div class="project-name">[[item.name]]</div>
                </template>

Does any one know what happens? In the beginning, I didn't use Promise, I thought it maybe because of asyc issues (when dom is rendered, still cannot get data to display), so I used Promise, but still got the same result (only can get data in console) Plus, is any better way (or example) to create a data service in Polymer 1? (I used to use Angular which can perfectly make this happen) Just want to create a component like which can support basic http requests (GET,POST,PUT,DELETE) to be used in another component? or make the data service as a behaviors (I tried but doesn't work very well) thank you so much in advanced!

Answer 1

Polymer needs to know that there is smth to do try calling

_getReviews: (event) => {
            this.set('reviews', event.detail.reviews);
            // can get the data successfully at here:
            console.log(this.reviews);
        }