GH-30717: [C#] Add ToString() methods to Arrow classes

[voidstar69]

What changes are included in this PR?

Implemented the ToString() method on classes ChunkedArray, Field, RecordBatch, Schema and Table.
I could not find the class DataType mentioned in the issue, perhaps it meant DateType?

Closes #30717.

• Closes: [C#] Add ToString() methods to Arrow classes #30717

[github-actions]

⚠️ GitHub issue #30717 has been automatically assigned in GitHub to PR creator.

[westonpace]

These are helpful but I don't know if they address the heart of the issue. My guess is the issue was asking for some kind of pretty printing support. Do you want to perhaps add a follow-up issue for actual table-printing support? For example, here is what the "to string" looks like in various other implementations:

Python:

pyarrow.Table
strings: string
ints: int32
floats: float
----
strings: [["one","two","three","four","five"]]
ints: [[1,2,3,4,5]]
floats: [[1,2,3,4,5]]

C++

strings: string
ints: int32
floats: float
----
strings:
  [
    [
      "one",
      "two",
      "three",
      "four",
      "five"
    ]
  ]
ints:
  [
    [
      1,
      2,
      3,
      4,
      5
    ]
  ]
floats:
  [
    [
      1,
      2,
      3,
      4,
      5
    ]
  ]

Rust:

RecordBatch { schema: Schema { fields: [Field { name: "strings", data_type: Utf8, nullable: false, dict_id: 0, dict_is_ordered: false, metadata: {} }, Field { name: "ints", data_type: Int32, nullable: false, dict_id: 0, dict_is_ordered: false, metadata: {} }, Field { name: "floats", data_type: Float64, nullable: false, dict_id: 0, dict_is_ordered: false, metadata: {} }], metadata: {} }, columns: [StringArray
[
  "one",
  "two",
  "three",
  "four",
  "five",
], PrimitiveArray<Int32>
[
  1,
  2,
  3,
  4,
  5,
], PrimitiveArray<Float64>
[
  1.0,
  2.0,
  3.0,
  4.0,
  5.0,
]], row_count: 5 }

[voidstar69]

These are helpful but I don't know if they address the heart of the issue. My guess is the issue was asking for some kind of pretty printing support. Do you want to perhaps add a follow-up issue for actual table-printing support? For example, here is what the "to string" looks like in various other implementations:

Python:

pyarrow.Table
strings: string
ints: int32
floats: float
----
strings: [["one","two","three","four","five"]]
ints: [[1,2,3,4,5]]
floats: [[1,2,3,4,5]]

C++

strings: string
ints: int32
floats: float
----
strings:
  [
    [
      "one",
      "two",
      "three",
      "four",
      "five"
    ]
  ]
ints:
  [
    [
      1,
      2,
      3,
      4,
      5
    ]
  ]
floats:
  [
    [
      1,
      2,
      3,
      4,
      5
    ]
  ]

Rust:

RecordBatch { schema: Schema { fields: [Field { name: "strings", data_type: Utf8, nullable: false, dict_id: 0, dict_is_ordered: false, metadata: {} }, Field { name: "ints", data_type: Int32, nullable: false, dict_id: 0, dict_is_ordered: false, metadata: {} }, Field { name: "floats", data_type: Float64, nullable: false, dict_id: 0, dict_is_ordered: false, metadata: {} }], metadata: {} }, columns: [StringArray
[
  "one",
  "two",
  "three",
  "four",
  "five",
], PrimitiveArray<Int32>
[
  1,
  2,
  3,
  4,
  5,
], PrimitiveArray<Float64>
[
  1.0,
  2.0,
  3.0,
  4.0,
  5.0,
]], row_count: 5 }

I see. I thought the original issue might have been about making these types easier to comprehend in a debugger, such as in Visual Studio. There the debugger invokes ToString on an object, which usually returns a single line of text which the debugger then displays. I think this current PR achieves that goal, although I cannot know the intent of the original issue.

I have now created issue #36777 for adding pretty printing methods.

[westonpace]

I agree it makes sense to put pretty printing somewhere else other than ToString. One more tiny change if you don't mind. Also, could you briefly add some calls to ToString in the unit tests for these types? You probably don't need to create a new test but just something to make sure it converts to string without triggering an exception.

[voidstar69]

I agree it makes sense to put pretty printing somewhere else other than ToString. One more tiny change if you don't mind. Also, could you briefly add some calls to ToString in the unit tests for these types? You probably don't need to create a new test but just something to make sure it converts to string without triggering an exception.

@westonpace, I think this PR is now ready for your review. Hopefully we can merge this PR soon. Thanks.

[voidstar69]

@westonpace are you able to review this PR now? Or is there somebody else who can do this? Thanks.

[voidstar69]

@westonpace

[voidstar69]

@davidhcoe are you or another maintainer available to review this PR please? This PR has not received a further review since @westonpace reviewed it in July. I have held off from creating further PRs due to this.

[CurtHagenlocher]

Sorry, meant to look last week but I couldn't figure out how to re-run the failed appveyor build. As I can't imagine it's related, I'll ignore it and cross my fingers... .

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 4 benchmarking runs that have been run so far on merge-commit 0026c0c.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details.