Here is my Promise Function that iterates through each blob in Azure BlobStorage and reads each blob. The console.log(download) displays the values as JSON.
However, when trying to close the new Promise function, I want the resolve function to return the JSON data from reading the blobstream. In my case, resolve does not lead to anything.
The code in Angular Service.ts file looks like this:
getData(): Promise<JsonData[]> {
return new Promise(async resolve => {
const containerName = "blobcontainer";
const containerClient = this.blobServiceClient.getContainerClient(containerName);
//list blobs
let i = 1;
async function main() {
i = 1;
for await (const blob of containerClient.listBlobsFlat()) {
console.log(`Blob ${i++}: ${blob.name}`);
const blockBlobClient = containerClient.getBlockBlobClient(blob.name);
//console.log(blockBlobClient)
const downloadBlockBlobResponse = await blockBlobClient.download(0);
const download = await blobToString(await downloadBlockBlobResponse.blobBody)
//console.log(downloadBlockBlobResponse)
console.log(download)
}
}
async function blobToString(blob: Blob): Promise<string> {
const fileReader = new FileReader();
return new Promise((resolve, reject) => {
fileReader.onloadend = (ev: any) => {
JSON.parse(ev.target!.result)
resolve(JSON.parse(ev.target!.result));
};
fileReader.onerror = reject;
fileReader.readAsText(blob);
});
}
const _blob = await main().catch((err) => {
console.error('message'); return null
});
resolve(_blob) //resolve should return downloaded JSON file, but it didn't
})
}
Then in the component file, I intend to retrieve the data from the resolve function, which should return JSON string variables like "name", "timestamp", "value". However, in my case, I receive metadata from the blob instead of the contents. This indicates that the service.ts file is not correctly programmed:
xy.component.ts
export class xyComponent implements OnInit {
@Input() title: string;
jsondata: JsonData;
name: String;
timestamp: string;
value: number;
private jsonlistService: JsonDataService;
jsondatas: JsonData[]=null;
constructor(private jsonService: JsonDataService) {
this.jsonlistService = jsonService;
}
ngOnInit(): void {
this.jsonlistService.getData()
.then(results => this.jsondatas = results);
console.log(this.jsonService)
}
}
EDIT:
Even if I return download at the main function, the resolve from main() still does not deliver the json string.
Second EDIT: Here are some snippets on how to return data:
async function main() {
i = 1;
for await (const blob of containerClient.listBlobsFlat()) {
console.log(`Blob ${i++}: ${blob.name}`);
const blockBlobClient = containerClient.getBlockBlobClient(blob.name);
//console.log(blockBlobClient)
const downloadBlockBlobResponse = await blockBlobClient.download(0);
const download = await blobToString(await downloadBlockBlobResponse.blobBody)
//console.log(downloadBlockBlobResponse)
console.log(download)
return download
}
}
But I am still unable to receive the downloaded file. The error persists. Any help would be greatly appreciated.