nushell/crates/nu-command/src/database/commands/where_.rs
Fernando Herrera 1cb449b2d1
Database commands (#5466)
* change query to statement

* internal functions and over definitions

* cargo fmt
2022-05-07 13:33:33 +01:00

114 lines
3.3 KiB
Rust

use crate::database::values::dsl::ExprDb;
use super::super::SQLiteDatabase;
use nu_engine::CallExt;
use nu_protocol::{
ast::Call,
engine::{Command, EngineState, Stack},
Category, Example, IntoPipelineData, PipelineData, ShellError, Signature, SyntaxShape, Value,
};
use sqlparser::ast::{Expr, Query, Select, SetExpr, Statement};
#[derive(Clone)]
pub struct WhereDb;
impl Command for WhereDb {
fn name(&self) -> &str {
"db where"
}
fn usage(&self) -> &str {
"Includes a where statement for a query"
}
fn signature(&self) -> Signature {
Signature::build(self.name())
.required("where", SyntaxShape::Any, "Where expression on the table")
.category(Category::Custom("database".into()))
}
fn search_terms(&self) -> Vec<&str> {
vec!["database", "where"]
}
fn examples(&self) -> Vec<Example> {
vec![Example {
description: "selects a column from a database with a where clause",
example: r#"db open db.mysql
| db select a
| db from table_1
| db where ((db col a) > 1)
| db describe"#,
result: None,
}]
}
fn run(
&self,
engine_state: &EngineState,
stack: &mut Stack,
call: &Call,
input: PipelineData,
) -> Result<PipelineData, ShellError> {
let value: Value = call.req(engine_state, stack, 0)?;
let expr = ExprDb::try_from_value(&value)?.into_native();
let mut db = SQLiteDatabase::try_from_pipeline(input, call.head)?;
match db.statement.as_mut() {
Some(statement) => match statement {
Statement::Query(query) => modify_query(query, expr),
s => {
return Err(ShellError::GenericError(
"Connection doesnt define a query".into(),
format!("Expected a connection with query. Got {}", s),
Some(call.head),
None,
Vec::new(),
))
}
},
None => {
return Err(ShellError::GenericError(
"Connection without statement".into(),
"The connection needs a statement defined".into(),
Some(call.head),
None,
Vec::new(),
))
}
};
Ok(db.into_value(call.head).into_pipeline_data())
}
}
fn modify_query(query: &mut Box<Query>, expression: Expr) {
match query.body {
SetExpr::Select(ref mut select) => modify_select(select, expression),
_ => {
query.as_mut().body = SetExpr::Select(Box::new(create_select(expression)));
}
};
}
fn modify_select(select: &mut Box<Select>, expression: Expr) {
select.as_mut().selection = Some(expression);
}
fn create_select(expression: Expr) -> Select {
Select {
distinct: false,
top: None,
into: None,
projection: Vec::new(),
from: Vec::new(),
lateral_views: Vec::new(),
selection: Some(expression),
group_by: Vec::new(),
cluster_by: Vec::new(),
distribute_by: Vec::new(),
sort_by: Vec::new(),
having: None,
}
}