JsonPropertyNames are ignored when using syntax to select individual columns.

[mrt181]

Describe the bug JsonPropertyNames are ignored when using syntax to selec individual columns.

To Reproduce

  public class JsonPropertyNameTestData
  {
    [JsonPropertyName("sub")] public SubProperty SubProperty { get; set; }
  }

  [Struct]
  public class SubProperty
  {
    [JsonPropertyName("prop")] public string Property { get; set; }
  }

  [Test]
  public void SelectColumnsUsingPullQueryThatHaveJsonPropertyName()
  {
    //Arrange
    //Act
    var ksql = DbProvider.CreatePullQuery<JsonPropertyNameTestData>()
      .Select(c => new { c.SubProperty })
      .ToQueryString();

    //Assert
    ksql.Should().BeEquivalentTo(
      @$"SELECT sub FROM {nameof(JsonPropertyNameTestData)};".ReplaceLineEndings());
  }

  [Test]
  public void SelectColumnsUsingPullQueryThatHaveJsonPropertyNameWithAlias()
  {
    //Arrange
    //Act
    var ksql = DbProvider.CreatePullQuery<JsonPropertyNameTestData>()
      .Select(c => new { Prop = c.SubProperty })
      .ToQueryString();

    //Assert
    ksql.Should().BeEquivalentTo(
      @$"SELECT sub As Prop FROM {nameof(JsonPropertyNameTestData)};".ReplaceLineEndings());
  }

Expected behavior Both Tests should work but only the second one with the alias does. The first one uses SubProperty as column name.

Environment (please complete the following information):

• ksqlDb version: 7.6.0
• ksqlDb.RestApi.Client Nuget package version 3.6.1]
• TFM net8.0

Additional context This is needed when selecting PseudoColumns like ROWTIME but will fail because a stream / table creates the column names using the JsonPropertyNames

[mrt181]

These are the places that seem related to this but I have currently no idea how to fix this. The moment I touch it many tests that use column selection syntax break.

[tomasfabian]

Hello @mrt181, this could be potentially fixed by adding the below else if branch before this line in KSqlVisitor.ProcessVisitNewMember:

    else if (expression is MemberExpression me2 && me2.Member.GetCustomAttribute<JsonPropertyNameAttribute>() != null)
      Append(me2.Member.Format(QueryMetadata.IdentifierEscaping));

I've just quickly prototyped it for now. Please share your thoughts and feedback on it.

[tomasfabian]

Alternative solution:

    else if (expression is MemberExpression me2 && !me2.Member.DeclaringType.IsKsqlGrouping())
      Append(me2.Member.Format(QueryMetadata.IdentifierEscaping));

[tomasfabian]

Do we want to implement the suggested fix mentioned above? If so, I can prepare a pull request (PR), or would you prefer to handle it yourself?

[mrt181]

I did an additional change to cover pseudocolumns and added some tests. If ok than I will create a PR.

[tomasfabian]

Thank you @mrt181 for the PR! I released a patch:

dotnet add package ksqlDb.RestApi.Client --version 3.6.2