Table Column with Default Expression

[billy1624]

Motivation

• Currently, we support column with default value but not default expression
• Having default expression in column such as timestamp / datetime is very common, e.g. CURRENT_TIMESTAMP as the default expression

Proposed Solutions

• ColumnSpec::Default(Value) should be changed to holding SimpleExpr, i.e. ColumnSpec::Default(SimpleExpr)
  

  sea-query/src/table/column.rs

  Lines 48 to 58 in 6c9527a

  	/// All column specification keywords
  	#[derive(Debug, Clone)]
  	pub enum ColumnSpec {
  	Null,
  	NotNull,
  	Default(Value),
  	AutoIncrement,
  	UniqueKey,
  	PrimaryKey,
  	Extra(String),
  	}

• Keep the old default method and introduce a new method called default_expr which take any Into<SimpleExpr>
  

  sea-query/src/table/column.rs

  Lines 142 to 149 in 6c9527a

  	/// Set default value of a column
  	pub fn default<T>(&mut self, value: T) -> &mut Self
  	where
  	T: Into<Value>,
  	{
  	self.spec.push(ColumnSpec::Default(value.into()));
  	self
  	}

[ikrivosheev]

@billy1624, hello! I will do this.

[billy1624]

Thanks! @ikrivosheev

[billy1624]

Related Discussion:

• Can I use postgresql "CURRENT_TIMESTAMP" as a default value? #346

[ikrivosheev]

@billy1624 what do you think about new Enum for table? We only need some variants from SimpleExpr

1. FuncionCall
2. Value
3. Custom

[ikrivosheev]

No, bad ideas... We need to split QueryBuilder. For unavailable operations panic.

[billy1624]

Hey @ikrivosheev, sorry for the delay.

@billy1624 what do you think about new Enum for table? We only need some variants from SimpleExpr

Do you mean introducing a new Enum for the "Default Value" of a column?

sea-query/src/table/column.rs

Lines 51 to 61 in 63e1894

	/// All column specification keywords
	#[derive(Debug, Clone)]
	pub enum ColumnSpec {
	Null,
	NotNull,
	Default(Value),
	AutoIncrement,
	UniqueKey,
	PrimaryKey,
	Extra(String),
	}

pub enum ColumnSpec {
...
    Default(DefaultValue)
...
}

// I just makeup the name, feel free to rename it :)
pub enum DefaultValue {
    Func(Function),
    Value(Value),
    Custom(String),
}

Something like this?

[ikrivosheev]

Hey @ikrivosheev, sorry for the delay.

@billy1624 what do you think about new Enum for table? We only need some variants from SimpleExpr

Do you mean introducing a new Enum for the "Default Value" of a column?

sea-query/src/table/column.rs

Lines 51 to 61 in 63e1894

	/// All column specification keywords
	#[derive(Debug, Clone)]
	pub enum ColumnSpec {
	Null,
	NotNull,
	Default(Value),
	AutoIncrement,
	UniqueKey,
	PrimaryKey,
	Extra(String),
	}

pub enum ColumnSpec {
...
    Default(DefaultValue)
...
}

// I just makeup the name, feel free to rename it :)
pub enum DefaultValue {
    Func(Function),
    Value(Value),
    Custom(String),
}

Something like this?

Yes

[ikrivosheev]

@billy1624 @tyt2y3 what do you think about custom Enum?

[tyt2y3]

1. I think we should rename the old default to default_value and the new default is an alias of default_expr
2. Yes I think having a dedicated DefaultColumnExpr is a good idea

[ikrivosheev]

@tyt2y3 @billy1624 hello! I have made several attempts and understand that is better to use SimpleExpr instead create DefaultColumnExpr

[tyt2y3]

I have no objection to either

[billy1624]

Hello @ikrivosheev, are you working on this?