DigitalTwinsClient.QueryAsync<T>(String, CancellationToken) Method

Reference

Definition

Namespace:: Azure.DigitalTwins.Core

Assembly:: Azure.DigitalTwins.Core.dll

Package:: Azure.DigitalTwins.Core v1.4.0

Source:: DigitalTwinsClient.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Queries for digital twins by iterating through a collection asynchronously.

public virtual Azure.AsyncPageable<T> QueryAsync<T> (string query, System.Threading.CancellationToken cancellationToken = default);

abstract member QueryAsync : string * System.Threading.CancellationToken -> Azure.AsyncPageable<'T>
override this.QueryAsync : string * System.Threading.CancellationToken -> Azure.AsyncPageable<'T>

Public Overridable Function QueryAsync(Of T) (query As String, Optional cancellationToken As CancellationToken = Nothing) As AsyncPageable(Of T)

Type Parameters

T

The type to deserialize the result to.

Parameters

query: String

The query string, in SQL-like syntax.

cancellationToken: CancellationToken

The cancellation token.

Returns

AsyncPageable<T>

The pageable list AsyncPageable<T> of query results.

Exceptions

RequestFailedException

The exception that captures the errors from the service. Check the ErrorCode and Status properties for more details.

Examples

// This code snippet demonstrates the simplest way to iterate over the digital twin results, where paging
// happens under the covers.
AsyncPageable<BasicDigitalTwin> asyncPageableResponse = client.QueryAsync<BasicDigitalTwin>("SELECT * FROM digitaltwins");

// Iterate over the twin instances in the pageable response.
// The "await" keyword here is required because new pages will be fetched when necessary,
// which involves a request to the service.
await foreach (BasicDigitalTwin twin in asyncPageableResponse)
{
    Console.WriteLine($"Found digital twin '{twin.Id}'");
}

Remarks

For more samples, see our repo samples. Note that there may be a delay between before changes in your instance are reflected in queries. For more details on query limitations, see Query limitations.

Applies to

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