Question

我正在寻找一种通过另一个ID流获取文件流的方法，假设我有一个param( [parameter(Mandatory=$true)] [String] $ResourceGroupName, [parameter(Mandatory=$true)] [String] $DatabaseServerName, [parameter(Mandatory=$true)] [String]$DatabaseAdminUsername, [parameter(Mandatory=$true)] [String]$DatabaseAdminPassword, [parameter(Mandatory=$true)] [String]$DatabaseNames, [parameter(Mandatory=$true)] [String]$StorageAccountName, [parameter(Mandatory=$true)] [String]$BlobStorageEndpoint, [parameter(Mandatory=$true)] [String]$StorageKey, [parameter(Mandatory=$true)] [string]$BlobContainerName # [parameter(Mandatory=$true)] # [Int32]$RetentionDays ) $ErrorActionPreference = 'stop' function Login() { $connectionName = "AzureRunAsConnection" try { $servicePrincipalConnection = Get-AutomationConnection -Name $connectionName Write-Verbose "Logging in to Azure..." -Verbose Add-AzureRmAccount ` -ServicePrincipal ` -TenantId $servicePrincipalConnection.TenantId ` -ApplicationId $servicePrincipalConnection.ApplicationId ` -CertificateThumbprint $servicePrincipalConnection.CertificateThumbprint | Out-Null } catch { if (!$servicePrincipalConnection) { $ErrorMessage = "Connection $connectionName not found." throw $ErrorMessage } else{ Write-Error -Message $_.Exception throw $_.Exception } } } function Create-Blob-Container([string]$blobContainerName, $storageContext) { Write-Verbose "Checking if blob container '$blobContainerName' already exists" -Verbose if (Get-AzureStorageContainer -ErrorAction "Stop" -Context $storageContext | Where-Object { $_.Name -eq $blobContainerName }) { Write-Verbose "Container '$blobContainerName' already exists" -Verbose } else { New-AzureStorageContainer -ErrorAction "Stop" -Name $blobContainerName -Permission Off -Context $storageContext Write-Verbose "Container '$blobContainerName' created" -Verbose } } function Export-To-Blob-Storage([string]$resourceGroupName, [string]$databaseServerName, [string]$databaseAdminUsername, [string]$databaseAdminPassword, [string[]]$databaseNames, [string]$storageKey, [string]$blobStorageEndpoint, [string]$blobContainerName) { Write-Verbose "Starting database export to databases '$databaseNames'" -Verbose $securePassword = ConvertTo-SecureString –String $databaseAdminPassword –AsPlainText -Force $creds = New-Object –TypeName System.Management.Automation.PSCredential –ArgumentList $databaseAdminUsername, $securePassword foreach ($databaseName in $databaseNames.Split(",").Trim()) { Write-Output "Creating request to backup database '$databaseName'" $bacpacFilename =$databaseName + "LiveBak_anon" + ".bacpac" $bacpacUri = $blobStorageEndpoint + "/" + $blobContainerName + "/" + $bacpacFilename $exportRequest = New-AzureRmSqlDatabaseExport -ResourceGroupName $resourceGroupName –ServerName $databaseServerName ` –DatabaseName $databaseName –StorageKeytype "StorageAccessKey" –storageKey $storageKey -StorageUri $BacpacUri ` –AdministratorLogin $creds.UserName –AdministratorLoginPassword $creds.Password -ErrorAction "Stop" # Print status of the export # Get-AzureRmSqlDatabaseImportExportStatus -OperationStatusLink $exportRequest.OperationStatusLink -ErrorAction "Stop" } } # function Delete-Old-Backups([int]$retentionDays, [string]$blobContainerName, $storageContext) { # Write-Output "Removing backups older than '$retentionDays' days from blob: '$blobContainerName'" # $isOldDate = [DateTime]::UtcNow.AddDays(-$retentionDays) # $blobs = Get-AzureStorageBlob -Container $blobContainerName -Context $storageContext # foreach ($blob in ($blobs | Where-Object { $_.LastModified.UtcDateTime -lt $isOldDate -and $_.BlobType -eq "BlockBlob" })) { # Write-Verbose ("Removing blob: " + $blob.Name) -Verbose # Remove-AzureStorageBlob -Blob $blob.Name -Container $blobContainerName -Context $storageContext # } # } Write-Verbose "Starting database backup" -Verbose $StorageContext = New-AzureStorageContext -StorageAccountName $storageAccountName -StorageAccountKey $storageKey Login Create-Blob-Container ` -blobContainerName $blobContainerName ` -storageContext $storageContext Export-To-Blob-Storage ` -resourceGroupName $ResourceGroupName ` -databaseServerName $DatabaseServerName ` -databaseAdminUsername $DatabaseAdminUsername ` -databaseAdminPassword $DatabaseAdminPassword ` -databaseNames $DatabaseNames ` -storageKey $StorageKey ` -blobStorageEndpoint $BlobStorageEndpoint ` -blobContainerName $BlobContainerName # Delete-Old-Backups ` # -retentionDays $RetentionDays ` # -storageContext $StorageContext ` # -blobContainerName $BlobContainerName Write-Verbose "Database backup script finished" -Verbose这样的文件ID流，然后我需要使用已经拥有的ID查询另一个集合请在下面找到我的代码，该代码返回空流。

Stream<List<String>> docIds = ['3dd34334, '45454de', ...]

Answer 1

您可以通过多种方式创建流，

使用收益率基本示例：

Stream<List<int>> countStream(int to) async* {
  for (int i = 1; i <= to; i++) {
    List<int> list = List<int>();
    yield list;
  }
}

现在有了firebase firestore和transforming the stream：

Stream<List<ViewModel>> matches(uid) async* {
   Stream<List<String>> docIds = FirebaseFirestore.instance
      .collection('matches')
      .where('match', arrayContains: uid)
      .snapshots()
      .map((event) => event.docs.map((e) => e.id).toList());
   await for (List<ViewModel> chunk in source) {
       // Do other operations if you need
       yield chunk
   }
}

Flutter通过ID列表获取Firestore文档流

1 个答案: