sea_schema/
probe.rs

1use sea_query::{Condition, Expr, Iden, Query, SelectStatement, SimpleExpr};
2
3pub trait SchemaProbe {
4    fn get_current_schema() -> SimpleExpr;
5
6    fn query_tables(&self) -> SelectStatement;
7
8    fn has_table<T>(&self, table: T) -> SelectStatement
9    where
10        T: AsRef<str>,
11    {
12        let mut subquery = self.query_tables();
13        subquery.cond_where(Expr::col(Schema::TableName).eq(table.as_ref()));
14        Query::select()
15            .expr_as(Expr::cust("COUNT(*) > 0"), Has::Table)
16            .from_subquery(subquery, Subquery)
17            .take()
18    }
19
20    fn has_column<T, C>(&self, table: T, column: C) -> SelectStatement
21    where
22        T: AsRef<str>,
23        C: AsRef<str>,
24    {
25        Query::select()
26            .expr_as(Expr::cust("COUNT(*) > 0"), Has::Column)
27            .from((Schema::Info, Schema::Columns))
28            .cond_where(
29                Condition::all()
30                    .add(
31                        Expr::expr(Self::get_current_schema())
32                            .equals((Schema::Columns, Schema::TableSchema)),
33                    )
34                    .add(Expr::col(Schema::TableName).eq(table.as_ref()))
35                    .add(Expr::col(Schema::ColumnName).eq(column.as_ref())),
36            )
37            .take()
38    }
39
40    fn has_index<T, C>(&self, table: T, index: C) -> SelectStatement
41    where
42        T: AsRef<str>,
43        C: AsRef<str>;
44}
45
46#[derive(Debug, Iden)]
47pub enum Has {
48    #[iden = "has_table"]
49    Table,
50    #[iden = "has_column"]
51    Column,
52    #[iden = "has_index"]
53    Index,
54}
55
56#[allow(clippy::enum_variant_names)]
57#[derive(Debug, Iden)]
58pub(crate) enum Schema {
59    #[iden = "information_schema"]
60    Info,
61    Columns,
62    TableName,
63    ColumnName,
64    TableSchema,
65}
66
67#[derive(Debug, Iden)]
68struct Subquery;
sea_schema/probe.rs

sea_schema/
probe.rs
