Embed metadata in a string - used to add data in database text columns

[smalers]

It is useful to embed metadata in a string. For example, a database column or Excel field may benefit from embedded metadata rather than adding a new column. Or maybe a database schema can't be changed but want to add metadata to a text column. Need general utility code for this.

[smalers]

I asked ChatGPT some questions:

---

I want to define properties as metadata in a string value. For example, using Java annotation syntax or a double slash comment followed by Property=Value. Show me different known syntax for this from various programming languages and protocols.
ChatGPT said:

Got it 👍 — you want to see different ways various languages and systems encode metadata/properties inline in text (often human-readable, sometimes machine-parsable).
Here’s a survey of known, common syntaxes across programming languages and protocols for embedding metadata or key–value properties into a string, file, or code.

1. Java / C# Annotations

Java:

@author(name = "Steve", date = "2025-09-24")

C#:

[Obsolete("Use NewMethod instead")]

2. Comments with key=value

Shell / Bash:

Property=Value

C / C++ / Java style:

// Timeout=30s

Python:

Author=Steve

3. INI / Properties File Style

Java .properties:

key=value
timeout=30

Windows .ini:

[Database]
user=admin
password=secret

4. YAML Front Matter (Markdown, Hugo, Jekyll)

---

title: "Example Document"
author: "Steve"
tags: ["metadata", "demo"]

5. XML Attributes or Elements

6. JSON Metadata
   {
   "timeout": 30,
   "enabled": true
   }

7. Python Decorators (annotation-like)
   @Retry(times=3, delay=2)
   def fetch_data():
   pass

8. Docstring / Javadoc Tags

Python docstring:

"""
:param timeout: 30
:return: data
"""

Java Javadoc:

/**

• @author Steve
• @Version 1.2
  */

9. HTTP Headers (Key: Value)
   Content-Type: application/json
   Cache-Control: no-cache
   X-Custom-Property: 42

10. SQL Comments with Metadata
    -- Author=Steve
    -- Version=2.1
    SELECT * FROM users;

11. Shebang & Pragmas

Unix shebang:

#!/usr/bin/env python3

C pragma:

#pragma optimize("", off)

12. Email / MIME Headers
    From: steve@example.com
    Subject: Test Email
    X-Meta-Flag: true

13. Protocol Buffers Options
    message Person {
    string name = 1 [(validate.rules).string = {min_len: 1}];
    }

✅ In summary:

Inline annotation/decorator syntax → Java, C#, Python, Protobuf.

Key=value comments → Shell, SQL, JSON5, JavaScript configs.

Standalone key=value config → INI, Properties, HTTP headers.

Structured metadata blocks → YAML front matter, JSON, XML.

Do you want me to focus on inline-in-string approaches (like embedding metadata in one string value), or do you want a broader catalog of file-level metadata styles like I started listing?

You said:
focus on embedding metadata in a string value.
ChatGPT said:

Perfect — let’s narrow this down to "metadata inside a string value" (not external files like YAML/INI).

Here are known syntaxes and conventions across languages and protocols for embedding metadata directly in a string:

1. Java Annotation-like
   String meta = "@author(name=Steve, date=2025-09-24)";

Pros: Familiar if you’re in a Java ecosystem.

Cons: Not standard unless you parse it yourself.

2. Key=Value Pairs in Comments
   String meta = "// Timeout=30; Retry=true; Owner=Steve";

Variants: //, #, ;, -- depending on language inspiration.

Often used as pseudo-metadata tags in logs and configs.

3. INI / Properties Style in a String
   String meta = "timeout=30\nretry=true\nowner=Steve";

Easy to parse line by line.

Java Properties.load() can handle this directly.

4. JSON Inline Metadata
   String meta = "{"timeout":30, "retry":true, "owner":"Steve"}";

Universally parsable.

Widely supported by libraries.

5. XML Inside String
   String meta = "<meta timeout="30" retry="true" owner="Steve"/>";

Self-describing but verbose.

6. YAML-like Inline Map
   String meta = "timeout: 30, retry: true, owner: Steve";

Human-readable, looser structure.

Could be parsed with YAML parser if you wrap it in {}.

7. URL Query String Style
   String meta = "timeout=30&retry=true&owner=Steve";

Compact.

Libraries exist (URLEncodedUtils, etc.).

Familiar to anyone using HTTP.

8. CSV or TSV with Key=Value
   String meta = "timeout=30,retry=true,owner=Steve";

Very lightweight.

Works well if you don’t need nesting.

9. Markdown / Docstring Tag Style
   String meta = "@timeout 30 @Retry true @owner Steve";

Inspired by Javadoc / Python docstring tags.

Easy to regex-parse.

10. Custom Hashtag or Bracket Notation
    String meta = "[timeout=30][retry=true][owner=Steve]";

or

String meta = "#timeout=30 #retry=true #owner=Steve";

Often used in chat commands, logging systems, or custom DSLs.

11. Protocol Buffers Style Options
    String meta = "(timeout=30, retry=true, owner="Steve")";

Similar to annotation but wrapped in parentheses.

Good if you want to mimic protobuf option syntax.

✅ Takeaway:
If you’re embedding metadata in a single string value, the most common and recognizable choices are:

JSON → rich structure, widely supported.

Query string / CSV with key=value → compact, quick parsing.

Annotation-like / Docstring-like tags → human-friendly, regex-friendly.

[smalers]

The formatting of the ChatGPT answer after pasting in is not very good. The questions can be asked independently if needed.

For a solution, first, need to define an enumeration to indicate the format of the comments. Then create a class that can store:

1. The original string.
2. The enumeration.
3. The value without the annotations.
4. The annotations parsed.

I've already done some work elsewhere using the following syntax, so start with double slash comment (//) syntax. Using double slash rather than, for example a hash (#) provides for a more unique indicator string that is more difficult to confuse with normal text. It is also easy to enter with less chance of errors. For example:

Some text. // Property1=Value2 Property2=Value2

Basic formatting is straightforward. The main issue is to handle some special cases such as:

Some text including https://some-url // Property1=Value1
Some text including https://some-url // Property1=https://some-url
Some text including // Property1="string with spaces"
Some text including // Property1="string with spaces 'and quotes'"
Some text including // Property1='string with spaces "and quotes'"'