Reducer

Read more about the article Implementing news feature in loklak

Implementing news feature in loklak

The idea is to bring out an useful feature out of the enriched high quality of data provided by api.loklak.org. Through this blog post, I’ll be discussing about the implementation of a news feature similar to Google to provide latest news relevant to the query in loklak. Creating news Component First step in implementing news feature would be to create a news component which would be rendered on clicking of news tab. ng g component feed/news Creating an action & reducer for news status This step involves creating an action & reducer function for tracking the status of news component on click of news tab. When the user will click on news tab, corresponding action would be dispatched to display the news component in feed. import { Action } from ‘@ngrx/store’; export const ActionTypes = { NEWS_STATUS: ‘[NEWS] NEWS STATUS’ }; export class NewsStatusAction implements Action { type = ActionTypes.NEWS_STATUS; constructor (public payload: boolean) { } } export type Actions = NewsStatusAction;   Corresponding reducer function for news status to store current news status would be: export function reducer(state: State = initialState, action: newsStatusAction.NewsStatusAction): State { switch (action.type) { case newsStatusAction.ActionTypes.NEWS_STATUS: { const newsStatusPayload: boolean = action.payload; return Object.assign({}, state, { newsStatus: newsStatusPayload }); } default: { return state; } } }   I would not be getting into each line of code here, only the important portions would be discussed here. Creating news-org to store the names of news organizations A new file news-org would be created inside app/shared/ folder containing list of news organizations in an array newsOrgs from which we would extract and filter results. export const newsOrgs = [ ‘CNN’, ‘nytimes’ ];   Note: This is a dynamic implementation of news service and hence, the list of news organizations can be easily modified/updated here. We would also need to export the newsOrgs in the index file inside shared/ folder as: export { newsOrgs } from ‘./news-org’; Creating ngrx action, reducer & effect for news success Now comes the main part. We would need an action to dispatch on successful response of news search and corresponding reducer to keep appending the async news results. News action would be created following the simple ngrx composition as: import { Action } from ‘@ngrx/store’; import { ApiResponse } from ‘../models/api-response’; export const ActionTypes = { NEWS_SEARCH_SUCCESS: ‘[NEWS] SEARCH SUCCESS’ }; export class NewsSearchSuccessAction implements Action { type = ActionTypes.NEWS_SEARCH_SUCCESS; constructor (public payload: ApiResponse) { } } export type Actions = NewsSearchSuccessAction;   One of the important parts of news implementation is the reducer function corresponding to the news success action. We would actually append the async results provided by news effect into the store. import * as newsSuccessAction from ‘../actions/newsSuccess’; import { ApiResponseResult } from ‘../models’; export interface State { newsResponse: ApiResponseResult[]; } export const initialState: State = { newsResponse: [], }; export function reducer(state: State = initialState, action: newsSuccessAction.NewsSearchSuccessAction): State { switch (action.type) { case newsSuccessAction.ActionTypes.NEWS_SEARCH_SUCCESS: { // Appending the news result return Object.assign({}, state, { newsResponse: […action.payload.statuses] });…

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Read more about the article Adding Unit Test for Reducer in loklak search

Adding Unit Test for Reducer in loklak search

Ngrx/store components are an integral part of the loklak search. All the components are dependent on how the data is received from the reducers. Reducer is like a client-side database which stores up all the data received from the API response. It is responsible for changing the state of the application. Reducers also supplies data to the Angular components from the central Store. If correct data is not received by the components, the application would crash. Therefore, we need to test if the reducer is storing the data in a correct way and changes the state of the application as expected. Reducer also stores the current state properties which are fetched from the APIs. We need to check if reducers store the data in a correct way and if the data is received from the reducer when called from the angular components. In this blog, I would explain how to build up different components for unit testing reducers. Reducer to test This reducer is used for store the data from suggest.json API from the loklak server.The data received from the server is further classified into three properties which can be used by the components to show up auto- suggestions related to current search query. metadata: - This property stores the metadata from API suggestion response. entities: - This property stores the array of suggestions corresponding to the particular query received from the server. valid: - This is a boolean which keeps a check if the suggestions are valid or not. We also have two actions corresponding to this reducer. These actions, when called, changes the state properties which , further, supplies data to the components in a more classified manner. Moreover, state properties also causes change in the UI of the component according to the action dispatched. SUGGEST_COMPLETE_SUCCESS: - This action is called when the data is received successfully from the server. SUGGEST_COMPLETE_FAIL: - This action is called when the retrieving data from the server fails. export interface State { metadata: SuggestMetadata; entities: SuggestResults[]; valid: boolean; }export const initialState: State = { metadata: null, entities: [], valid: true };export function reducer(state: State = initialState, action: suggestAction.Actions): State { switch (action.type) { case suggestAction.ActionTypes.SUGGEST_COMPLETE_SUCCESS: { const suggestResponse = action.payload;return { metadata: suggestResponse.suggest_metadata, entities: suggestResponse.queries, valid: true }; }case suggestAction.ActionTypes.SUGGEST_COMPLETE_FAIL: { return Object.assign({}, state, { valid: false }); }default: { return state; } } } Unit tests for reducers Import all the actions, reducers and mocks import * as fromSuggestionResponse from './suggest-response'; import * as suggestAction from '../actions/suggest'; import { SuggestResponse } from '../models/api-suggest'; import { MockSuggestResponse } from '../shared/mocks/suggestResponse.mock';   Next, we are going to test if the undefined action doesn’t a cause change in the state and returns the initial state properties. We will be creating an action by const action = {} as any;  and call the reducer by const result = fromSuggestionResponse.reducer(undefined, action);. Now we will be making assertions with expect() block to check if the result is equal to initialState and all the initial state properties are…

Continue ReadingAdding Unit Test for Reducer in loklak search