Getting System.Text.Json exception when reading from Azure Storage Table as an ITableEntity in Azure queue-triggered functions

Question

I am following this example by Microsoft to read a table entity from an azure storage account's table but I am getting the following error message:

Error:System.Text.Json.JsonException: The JSON value could not be converted to MyModels.MyTableData. Path: $ | LineNumber: 0 | BytePositionInLine: 1.

When I read the table's content as an object I see the table entity's data in a Json format but it cannot be deserialized into the target object implementing ITableEntity. What am I missing in this excercise?

Answer 1

To get table from Azure Storage and by using ITableEntity, you can use below code which worked for me:

Function1.cs:

using System;
using System.Collections.Generic;
using System.Text.Json;
using Microsoft.Azure.WebJobs;
using Microsoft.Extensions.Logging;
using Azure.Data.Tables;
using Microsoft.Extensions.Configuration;
using Azure;

namespace FunctionApp100
{
    public class RithTable : ITableEntity
    {
        public string Name { get; set; }
        public string PartitionKey { get; set; }
        public string RowKey { get; set; }
        public DateTimeOffset? Timestamp { get; set; }
        public string Id { get; set; }
        public ETag ETag { get; set; }
    }

    public static class Function1
    {
        [FunctionName("Function1")]
        public static void Run(
            [QueueTrigger("myqueue-items", Connection = "rithconec")] string rith,
            ILogger log,
            ExecutionContext context)
        {
            log.LogInformation($"Hello Rithwik Bojja, The Table name given in Queue is : {rith}");
            var rithconf = new ConfigurationBuilder()
                .SetBasePath(context.FunctionAppDirectory)
                .AddJsonFile("local.settings.json", optional: true, reloadOnChange: true)
                .AddEnvironmentVariables()
                .Build();

            var rithcon = rithconf["Values:rithconec"]; 
            var RithTable = rith; 
            var rith_tc = new TableClient(rithcon, RithTable);
            var rith_ent = new List<RithTable>();
            foreach (var ri in rith_tc.Query<RithTable>())
            {
                rith_ent.Add(ri);

            }
            foreach (var ri in rith_ent)
            {
                var rith_ser = JsonSerializer.Serialize(ri);
                log.LogInformation($"Hello Rithwik Bojja, The Serialized Value is : {rith_ser}");
            }
        }
    }
}

csproj:

<Project Sdk="Microsoft.NET.Sdk">
    <PropertyGroup>
        <TargetFramework>net6.0</TargetFramework>
        <AzureFunctionsVersion>v4</AzureFunctionsVersion>
        <UserSecretsId>7d9865g n-7gs80-9931</UserSecretsId>
        <NoWarn>NU1605</NoWarn>
    </PropertyGroup>
    <ItemGroup>
        <PackageReference Include="Azure.Data.Tables" Version="12.8.3" />
        <PackageReference Include="Azure.Storage.Blobs" Version="12.16.0" />
        <PackageReference Include="Azure.Storage.Files.Shares" Version="12.1.0" />
        <PackageReference Include="Azure.Storage.Queues" Version="12.14.0" />
        <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.Storage" Version="5.3.0" />
        <PackageReference Include="Microsoft.Extensions.Azure" Version="1.6.3" />
        <PackageReference Include="Microsoft.Extensions.Configuration.UserSecrets" Version="6.0.1" />
        <PackageReference Include="Microsoft.NET.Sdk.Functions" Version="4.2.0" />
        <PackageReference Include="Microsoft.Azure.WebJobs.Extensions.Tables" Version="1.2.1" />
    </ItemGroup>
    <ItemGroup>
        <None Update="host.json">
            <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
        </None>
        <None Update="local.settings.json">
            <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
            <CopyToPublishDirectory>Never</CopyToPublishDirectory>
        </None>
    </ItemGroup>
</Project>

local.settings.json:

{
    "IsEncrypted": false,
  "Values": {
    "AzureWebJobsStorage": "UseDevelopmentStorage=true",
    "FUNCTIONS_WORKER_RUNTIME": "dotnet",
    "rithconec": "constrng"
  }
}

Table in Storage Account:

Output: