ColumnDef with default expression

[billy1624]

PR Info

• Closes Table Column with Default Expression #347

Adds

• ColumnDef::default_expr() setting the default expression of a column
• ColumnDef::default_value() setting the default value of a column

Breaking Changes

• ColumnDef::default() now takes Into<SimpleExpr> instead of Into<Value>. Users are advised to use ColumnDef::default_value().

[billy1624]

Hey @ikrivosheev, I remember you said you got some ideas for this PR?

[ikrivosheev]

Hey @ikrivosheev, I remember you said you got some ideas for this PR?

@billy1624 hello! Sorry for delay. I worked on this task and came to the conclusion that we need new trait:

pub trait SqlWriter: Write {
    fn push_param(&mut self, value: &Value, query_builder: &dyn QueryBuilder);
    fn query(self) -> String;
}

And two new struct:

pub struct SqlStringWriter {
    query: String,
}

and

pub struct SqlWriterObj {  // TODO: better name
    counter: usize,
    placeholder: String,
    numbered: bool,
    values: Vec<Value>,
    query: String,
}

And the backend will no longer have to worry about where and how to put the parameter. What do you think? I can create draft PR.

[ikrivosheev]

Hey @ikrivosheev, I remember you said you got some ideas for this PR?

@billy1624 hello! Sorry for delay. I worked on this task and came to the conclusion that we need new trait:

pub trait SqlWriter: Write {
    fn push_param(&mut self, value: &Value, query_builder: &dyn QueryBuilder);
    fn query(self) -> String;
}

And two new struct:

pub struct SqlStringWriter {
    query: String,
}

and

pub struct SqlWriterObj {  // TODO: better name
    counter: usize,
    placeholder: String,
    numbered: bool,
    values: Vec<Value>,
    query: String,
}

And the backend will no longer have to worry about where and how to put the parameter. What do you think? I can create draft PR.

@tyt2y3 what do you think about it?

[billy1624]

Cool! If I understand it correctly. @ikrivosheev

1. Both SqlStringWriter and SqlWriterObj implement SqlWriter trait.
2. Then queries (e.g. CRUD operations on table) that require value binding use SqlWriterObj to store the SQL and bindings.
3. Schema queries (e.g. CRUD operations on schema definition) that doesn't require value binding use SqlStringWriter to store the SQL and values are serialized as part of the SQL.

[ikrivosheev]

Cool! If I understand it correctly. @ikrivosheev

1. Both SqlStringWriter and SqlWriterObj implement SqlWriter trait.
2. Then queries (e.g. CRUD operations on table) that require value binding use SqlWriterObj to store the SQL and bindings.
3. Schema queries (e.g. CRUD operations on schema definition) that doesn't require value binding use SqlStringWriter to store the SQL and values are serialized as part of the SQL.

Yes, exactly! I started work on that. If you want, I can prepare draft PR.

[billy1624]

Feel free to work on that :D

[ikrivosheev]

@billy1624 hello! I create draft PR: #436

[tyt2y3]

I think we don't need this now since #436 is merged?

[billy1624]

I think we don't need this now since #436 is merged?

Correct!