CODEWITHSUNDEEP
c#.netazureazure-table-storage
ddavid09
ddavid09

Reputation: 21

Azure Table Storage null values in query result

I am building project to store sensors data from IoT devices. I use IoT Hub, Stream Analytics and Table Storage.

I have Web API which I want to return values from Table in Table Storage. I don't know why I getting null values in response from Table Storage only in custom columns. I know that columns in Table Storage are case-sensitive and I remembered about it.

What is really interesting when I add Row to Table from .NET SDK and next query it also with SDK, I'm getting correct values (not null :) )

This is how data looks like in Storage Explorer in Azure Portal:

my data in table storage

This shows that columns have correct case-sensitive names:

column names in table storage

Here is TableValue Entity from my code:

public class TableValue : TableEntity
{
    public TableValue() { }

    public TableValue(string id, string deviceId)
    {
        PartitionKey = deviceId;
        RowKey = id;
    }

    public string Humidity { get; set; }
    public string Pressure { get; set; }
    public string Temperature { get; set; }
    public string SentTimestamp { get; set; }
}

Here is my code responsible for querying values from table storage

public async Task<List<TableValue>> Handle(Query request, CancellationToken cancellationToken)
{
            var table = _tableClient.GetTableReference("iotinsights");              
            var condition = TableQuery.GenerateFilterCondition("PartitionKey", QueryComparisons.Equal, "Develop1");
            var query = new TabyleQuery<TableValue>().Where(condition);
            var result = table.ExecuteQuery(query);

            return await Task.FromResult(result.ToList());
 }

Here is result I got from request in Postman:

    {
        "humidity": null,
        "pressure": null,
        "temperature": null,
        "sentTimestamp": null,
        "partitionKey": "Develop1",
        "rowKey": "0131560c-d1d7-4dc3-93f0-14a4c676baa5",
        "timestamp": "2020-12-28T12:21:55.9198819+01:00",
        "eTag": "W/\"datetime'2020-12-28T11%3A21%3A55.9198819Z'\""
    },
    {
        "humidity": null,
        "pressure": null,
        "temperature": null,
        "sentTimestamp": null,
        "partitionKey": "Develop1",
        "rowKey": "022bc3f8-c8d5-4ff5-88b6-57e53c720aa9",
        "timestamp": "2020-12-28T12:27:22.9991905+01:00",
        "eTag": "W/\"datetime'2020-12-28T11%3A27%3A22.9991905Z'\""
    }, ...

What should I do to get correct values from this Table?

Upvotes: 1

Views: 791

Answers (1)

ddavid09
ddavid09

Reputation: 21

I found solution, it was easier than i thought. Custom Table Entity properties must have correct data types

    public class TableValue : TableEntity
{
    public TableValue() { }

    public TableValue(string id, string deviceId)
    {
        PartitionKey = deviceId;
        RowKey = id;
    }

    public Double? Humidity { get; set; }
    public Double? Pressure { get; set; }
    public Double? Temperature { get; set; }
    public DateTime? SentTimestamp { get; set; }
    
}

Upvotes: 1

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