🛠️ fix(generator): fix map should not use default value for un null types

[KiddoV]

Related issue #29

I also add check for DateTime and DateTime?instead of just check forcreatedAtandmodifiedAt. All DateTime` values should be treated the same.

[gemini-code-assist]

Summary of Changes

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This pull request addresses a critical issue in the data generator where non-nullable types were incorrectly assigned default values during map deserialization, potentially leading to data integrity problems. It also significantly refines the handling of DateTime types, making the parsing logic more generic and robust, and introduces proper support for nullable DateTime and Color fields. The changes improve the reliability of data deserialization and provide more explicit error reporting for invalid date formats.

Highlights

• Corrected Default Value Assignment: Removed default value assignments for non-nullable types (e.g., int, String, bool, double, Duration, Uri, BigInt, List, Color) when deserializing from a map. This ensures that null values from the map are not silently converted to defaults for non-nullable fields, aligning with sound null safety principles.
• Enhanced DateTime Handling: Generalized DateTime parsing logic to apply to all DateTime fields, not just 'createdAt' and 'modifiedAt'. This provides consistent and correct deserialization for all non-nullable DateTime properties.
• Added Nullable DateTime and Color Support: Introduced specific handling for DateTime? and Color? types, allowing them to be correctly deserialized as null if the source map value is null, preventing incorrect default value assignments for nullable fields.
• Improved Date Parsing Error Handling: Modified the _ParseDate utility function to throw an ArgumentError when an invalid date string is encountered. This provides clearer error feedback instead of returning a default DateTime from the epoch.

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Changelog

• packages/datum_generator/lib/src/datum_generator.dart
  • Removed default value assignments for various non-nullable types (e.g., int, String, bool, double, Duration, Uri, BigInt, Color, List) during map deserialization.
  • Generalized the parsing logic for non-nullable DateTime fields to apply based on type rather than specific field names.
  • Added new deserialization logic for nullable DateTime? and Color? types, allowing them to be null.
  • Updated the _ParseDate utility function to throw an ArgumentError for invalid date string inputs instead of returning a default DateTime.

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[gemini-code-assist]

Code Review

This pull request correctly addresses an issue where default values were used for non-nullable types during deserialization from a map. Removing these default values is a great improvement for correctness, as it will now fail fast on missing data instead of silently using a default. The generalization of DateTime handling and the improved error handling in the date parsing function are also welcome changes. I have one suggestion to improve the readability and efficiency of the generated code for double and double? types by reducing code repetition.

[gemini-code-assist]

The expression for handling double is quite repetitive. The sub-expression (map['$mapKey'] ?? map['${_camelToSnake(fieldName)}']) is evaluated up to three times. This makes the generated code less efficient and harder to read.

You could use an immediately-invoked function expression (IIFE) to store the value in a temporary variable and avoid repetition. This would also apply to the double? case on line 735.

Suggested change

	" $fieldName: (map['$mapKey'] ?? map['${_camelToSnake(fieldName)}']) is int ? (map['$mapKey'] ?? map['${_camelToSnake(fieldName)}']).toDouble() : (map['$mapKey'] ?? map['${_camelToSnake(fieldName)}']) as double,",
	" $fieldName: ((){ final v = map['$mapKey'] ?? map['${_camelToSnake(fieldName)}']; return v is int ? v.toDouble() : v as double; })(),"

[KiddoV]

This might be conflict and need to be resolved with PR #30