Added import/export functionality for censuses

src/api/census.ts

@@ -11,6 +11,8 @@ enum CensusAPIMethods {
   SIZE = '/censuses/{id}/size',
   WEIGHT = '/censuses/{id}/weight',
   TYPE = '/censuses/{id}/type',
+  EXPORT = '/censuses/{id}/export',
+  IMPORT = '/censuses/{id}/import',
 }
 
 interface ICensusCreateResponse {
@@ -34,6 +36,30 @@ export interface ICensusPublishResponse {
   uri: string;
 }
 
+export interface ICensusExportResponse {
+  /**
+   * The type of the census
+   */
+  type: number;
+
+  /**
+   * The root hash of the census
+   */
+  rootHash: string;
+
+  /**
+   * The data of the census
+   */
+  data: string;
+
+  /**
+   * The max levels of the census
+   */
+  maxLevels: number;
+}
+
+export interface ICensusImportResponse {}
+
 export interface ICensusProofResponse {
   /**
    * The type of the census
@@ -185,6 +211,58 @@ export abstract class CensusAPI extends API {
       .catch(this.isApiError);
   }
 
+  /**
+   * Exports the given census identifier
+   *
+   * @param {string} url API endpoint URL
+   * @param {string} authToken Authentication token
+   * @param {string} censusId The census ID we want to export
+   * @returns {Promise<ICensusExportResponse>} on success
+   */
+  public static export(url: string, authToken: string, censusId: string): Promise<ICensusExportResponse> {
+    return axios
+      .get<ICensusExportResponse>(url + CensusAPIMethods.EXPORT.replace('{id}', censusId), {
+        headers: {
+          Authorization: 'Bearer ' + authToken,
+        },
+      })
+      .then((response) => response.data)
+      .catch(this.isApiError);
+  }
+
+  /**
+   * Imports data into the given census identifier
+   *
+   * @param {string} url API endpoint URL
+   * @param {string} authToken Authentication token
+   * @param {string} censusId The census ID we want to export
+   * @param {number} type The type of the census
+   * @param {string} rootHash The root hash of the census
+   * @param {string} data The census data to be imported
+   * @returns {Promise<void>} on success
+   */
+  public static import(
+    url: string,
+    authToken: string,
+    censusId: string,
+    type: number,
+    rootHash: string,
+    data: string
+  ): Promise<ICensusImportResponse> {
+    return axios
+      .post<ICensusImportResponse>(
+        url + CensusAPIMethods.IMPORT.replace('{id}', censusId),
+        { type, rootHash, data },
+        {
+          headers: {
+            Authorization: 'Bearer ' + authToken,
+          },
+        }
+      )
+      .then((response) => response.data)
+      .catch(this.isApiError);
+  }
+
   /**
    * Returns the size of a given census
    *

src/client.ts

@@ -471,7 +471,7 @@ export class VocdoniSDKClient {
     if (!election.census.isPublished) {
       await this.censusService.createCensus(election.census as PlainCensus | WeightedCensus);
     } else if (!election.maxCensusSize && !election.census.size) {
-      await this.censusService.fetchCensusInfo(election.census.censusId).then((censusInfo) => {
+      await this.censusService.get(election.census.censusId).then((censusInfo) => {
         election.census.size = censusInfo.size;
         election.census.weight = censusInfo.weight;
       });
@@ -820,7 +820,7 @@ export class VocdoniSDKClient {
    * @returns {Promise<{size: number, weight: bigint}>}
    */
   fetchCensusInfo(censusId: string): Promise<{ size: number; weight: bigint; type: CensusType }> {
-    return this.censusService.fetchCensusInfo(censusId);
+    return this.censusService.get(censusId);
   }
 
   /**

src/services/census.ts

@@ -1,6 +1,6 @@
 import { Service, ServiceProperties } from './service';
 import { CensusType, ICensusParticipant, PlainCensus, WeightedCensus } from '../types';
-import { CensusAPI, ICensusPublishResponse, WalletAPI } from '../api';
+import { CensusAPI, ICensusImportResponse, ICensusPublishResponse, WalletAPI } from '../api';
 import { Wallet } from '@ethersproject/wallet';
 import invariant from 'tiny-invariant';
 
@@ -13,7 +13,7 @@ type CensusServiceParameters = ServiceProperties & CensusServiceProperties;
 
 type CensusAuth = {
   identifier: string;
-  wallet: Wallet;
+  wallet?: Wallet;
 };
 
 /**
@@ -31,6 +31,20 @@ export type CensusProof = {
   siblings?: Array<string>;
 };
 
+/**
+ * @typedef CensusImportExport
+ * @property {number} type
+ * @property {string} rootHash
+ * @property {string} data
+ * @property {number} maxLevels
+ */
+export type CensusImportExport = {
+  type: number;
+  rootHash: string;
+  data: string;
+  maxLevels: number;
+};
+
 /**
  * @typedef CspCensusProof
  * @property {string} type
@@ -63,9 +77,9 @@ export class CensusService extends Service implements CensusServiceProperties {
    * Fetches the information of a given census.
    *
    * @param censusId
-   * @returns {Promise<{size: number, weight: bigint}>}
+   * @returns {Promise<{size: number, weight: bigint, type: CensusType}>}
    */
-  fetchCensusInfo(censusId: string): Promise<{ size: number; weight: bigint; type: CensusType }> {
+  get(censusId: string): Promise<{ size: number; weight: bigint; type: CensusType }> {
     invariant(this.url, 'No URL set');
 
     return Promise.all([
@@ -105,12 +119,12 @@ export class CensusService extends Service implements CensusServiceProperties {
     }));
   }
 
-  create(censusType: CensusType): Promise<string> {
+  create(censusType: CensusType): Promise<{ id: string; auth: string }> {
     invariant(this.url, 'No URL set');
 
     return this.fetchAccountToken()
       .then(() => CensusAPI.create(this.url, this.auth.identifier, censusType))
-      .then((response) => response.censusID);
+      .then((response) => ({ id: response.censusID, auth: this.auth.identifier }));
   }
 
   async add(censusId: string, participants: ICensusParticipant[]) {
@@ -169,6 +183,31 @@ export class CensusService extends Service implements CensusServiceProperties {
     return CensusAPI.publish(this.url, this.auth.identifier, censusId);
   }
 
+  /**
+   * Exports the given census identifier.
+   *
+   * @param {string} censusId The census identifier
+   */
+  export(censusId: string): Promise<CensusImportExport> {
+    invariant(this.url, 'No URL set');
+    invariant(this.auth, 'No census auth set');
+
+    return CensusAPI.export(this.url, this.auth.identifier, censusId);
+  }
+
+  /**
+   * Imports data into the given census identifier.
+   *
+   * @param {string} censusId The census identifier
+   * @param {CensusImportExport} data The census data
+   */
+  import(censusId: string, data: CensusImportExport): Promise<ICensusImportResponse> {
+    invariant(this.url, 'No URL set');
+    invariant(this.auth, 'No census auth set');
+
+    return CensusAPI.import(this.url, this.auth.identifier, censusId, data.type, data.rootHash, data.data);
+  }
+
   /**
    * Publishes the given census.
    *
@@ -177,7 +216,7 @@ export class CensusService extends Service implements CensusServiceProperties {
    */
   createCensus(census: PlainCensus | WeightedCensus): Promise<void> {
     return this.create(census.type)
-      .then((censusId) => this.add(censusId, census.participants))
+      .then((censusInfo) => this.add(censusInfo.id, census.participants))
       .then((censusId) => this.publish(censusId))
       .then((censusPublish) => {
         census.censusId = censusPublish.censusID;
@@ -198,9 +237,9 @@ export class CensusService extends Service implements CensusServiceProperties {
    */
   // @ts-ignore
   private createCensusParallel(census: PlainCensus | WeightedCensus): Promise<void> {
-    return this.create(census.type).then((censusId) =>
-      Promise.all(this.addParallel(censusId, census.participants))
-        .then(() => this.publish(censusId))
+    return this.create(census.type).then((censusInfo) =>
+      Promise.all(this.addParallel(censusInfo.id, census.participants))
+        .then(() => this.publish(censusInfo.id))
         .then((censusPublish) => {
           census.censusId = censusPublish.censusID;
           census.censusURI = censusPublish.uri;

src/services/election.ts

@@ -82,7 +82,7 @@ export class ElectionService extends Service implements ElectionServicePropertie
     const electionInfo = await ElectionAPI.info(this.url, electionId);
 
     return this.censusService
-      .fetchCensusInfo(electionInfo.census.censusRoot)
+      .get(electionInfo.census.censusRoot)
       .then((censusInfo) =>
         PublishedElection.build({
           id: electionInfo.electionId,

test/services/census.test.ts

@@ -10,6 +10,8 @@ const pad = (num, size) => {
   return num;
 };
 
+let census, censusPublish;
+
 describe('Census Service tests', () => {
   it('should have the correct type and properties', () => {
     const service = new CensusService({});
@@ -54,7 +56,7 @@ describe('Census Service tests', () => {
     expect(census.size).toEqual(numVotes);
     expect(census.weight).toEqual(BigInt(55));
 
-    const censusInfo = await service.fetchCensusInfo(census.censusId);
+    const censusInfo = await service.get(census.censusId);
     expect(censusInfo.type).toEqual(CensusType.WEIGHTED);
     expect(censusInfo.size).toEqual(10);
     expect(censusInfo.weight).toEqual(BigInt(55));
@@ -78,7 +80,7 @@ describe('Census Service tests', () => {
     expect(census.size).toEqual(numVotes);
     expect(census.weight).toEqual(BigInt(numVotes));
 
-    const censusInfo = await service.fetchCensusInfo(census.censusId);
+    const censusInfo = await service.get(census.censusId);
     expect(censusInfo.type).toEqual(CensusType.WEIGHTED);
     expect(censusInfo.size).toEqual(numVotes);
     expect(censusInfo.weight).toEqual(BigInt(numVotes));
@@ -102,9 +104,50 @@ describe('Census Service tests', () => {
     expect(census.size).toEqual(numVotes);
     expect(census.weight).toEqual(BigInt(numVotes));
 
-    const censusInfo = await service.fetchCensusInfo(census.censusId);
+    const censusInfo = await service.get(census.censusId);
     expect(censusInfo.type).toEqual(CensusType.WEIGHTED);
     expect(censusInfo.size).toEqual(numVotes);
     expect(censusInfo.weight).toEqual(BigInt(numVotes));
   }, 40000);
+  it('should create a census and export/import it correctly', async () => {
+    const numVotes = 10;
+    const service = new CensusService({ url: URL, chunk_size: CENSUS_CHUNK_SIZE });
+    const participants: Wallet[] = [...new Array(numVotes)].map(() => Wallet.createRandom());
+
+    census = await service.create(CensusType.WEIGHTED);
+    const newCensus = await service.create(CensusType.WEIGHTED);
+
+    await service.add(
+      census.id,
+      participants.map((p) => ({ key: p.address, weight: BigInt(1) }))
+    );
+
+    const exportedCensus = await service.export(census.id);
+    await service.import(newCensus.id, exportedCensus);
+    censusPublish = await service.publish(census.id);
+
+    const censusInfo = await service.get(census.id);
+    const newCensusInfo = await service.get(newCensus.id);
+
+    expect(censusInfo.type).toEqual(newCensusInfo.type);
+    expect(censusInfo.size).toEqual(newCensusInfo.size);
+    expect(censusInfo.weight).toEqual(newCensusInfo.weight);
+  }, 30000);
+  it('should reuse a census, modify it and publish it again', async () => {
+    if (!census) {
+      return;
+    }
+    const service = new CensusService({ url: URL, chunk_size: CENSUS_CHUNK_SIZE, auth: { identifier: census.auth } });
+    const oldCensusInfo = await service.get(census.id);
+
+    await service.add(census.id, [{ key: Wallet.createRandom().address, weight: BigInt(1) }]);
+
+    const newCensusPublish = await service.publish(census.id);
+    const newCensusInfo = await service.get(census.id);
+
+    expect(newCensusInfo.type).toEqual(oldCensusInfo.type);
+    expect(newCensusInfo.size).toEqual(oldCensusInfo.size + 1);
+    expect(newCensusInfo.weight).toEqual(oldCensusInfo.weight + BigInt(1));
+    expect(newCensusPublish.uri).not.toEqual(censusPublish.uri);
+  }, 30000);
 });