dbmcp_postgres/tools/
list_triggers.rs

1//! MCP tool: `listTriggers`.
2
3use std::borrow::Cow;
4
5use dbmcp_server::pagination::Pager;
6use dbmcp_server::types::{ListTriggersRequest, ListTriggersResponse};
7use dbmcp_sql::Connection as _;
8use dbmcp_sql::sanitize::validate_ident;
9use rmcp::handler::server::router::tool::{AsyncTool, ToolBase};
10use rmcp::model::{ErrorData, ToolAnnotations};
11
12use crate::PostgresHandler;
13
14/// Marker type for the `listTriggers` MCP tool.
15pub(crate) struct ListTriggersTool;
16
17impl ListTriggersTool {
18    const NAME: &'static str = "listTriggers";
19    const TITLE: &'static str = "List Triggers";
20    const DESCRIPTION: &'static str = r#"List all user-defined triggers on tables in the `public` schema of a database. Internal constraint and foreign-key triggers are excluded.
21
22<usecase>
23Use when:
24- Investigating side-effects on INSERT/UPDATE/DELETE for a table
25- Auditing trigger coverage across a database
26- The user asks what triggers fire in a database
27</usecase>
28
29<examples>
30✓ "What triggers are in the mydb database?" → listTriggers(database="mydb")
31✓ "Does an order-audit trigger exist?" → listTriggers to check
32✗ "Show me a trigger's body" → use readQuery against pg_trigger or information_schema.triggers
33</examples>
34
35<what_it_returns>
36A sorted JSON array of trigger name strings.
37</what_it_returns>
38
39<pagination>
40Paginated. Pass the prior response's `nextCursor` as `cursor` to fetch the next page.
41</pagination>"#;
42}
43
44impl ToolBase for ListTriggersTool {
45    type Parameter = ListTriggersRequest;
46    type Output = ListTriggersResponse;
47    type Error = ErrorData;
48
49    fn name() -> Cow<'static, str> {
50        Self::NAME.into()
51    }
52
53    fn title() -> Option<String> {
54        Some(Self::TITLE.into())
55    }
56
57    fn description() -> Option<Cow<'static, str>> {
58        Some(Self::DESCRIPTION.into())
59    }
60
61    fn annotations() -> Option<ToolAnnotations> {
62        Some(
63            ToolAnnotations::new()
64                .read_only(true)
65                .destructive(false)
66                .idempotent(true)
67                .open_world(false),
68        )
69    }
70}
71
72impl AsyncTool<PostgresHandler> for ListTriggersTool {
73    async fn invoke(handler: &PostgresHandler, params: Self::Parameter) -> Result<Self::Output, Self::Error> {
74        handler.list_triggers(params).await
75    }
76}
77
78impl PostgresHandler {
79    /// Lists one page of user-defined triggers on tables in the `public` schema.
80    ///
81    /// # Errors
82    ///
83    /// Returns [`ErrorData`] with code `-32602` if `cursor` is malformed,
84    /// or an internal-error [`ErrorData`] if `database` is invalid
85    /// or the underlying query fails.
86    pub async fn list_triggers(
87        &self,
88        ListTriggersRequest { database, cursor }: ListTriggersRequest,
89    ) -> Result<ListTriggersResponse, ErrorData> {
90        let database = database
91            .as_deref()
92            .map(str::trim)
93            .filter(|s| !s.is_empty())
94            .map(validate_ident)
95            .transpose()?;
96
97        let pager = Pager::new(cursor, self.config.page_size);
98        let query = format!(
99            r"
100            SELECT t.tgname
101            FROM pg_trigger t
102            JOIN pg_class c ON t.tgrelid = c.oid
103            JOIN pg_namespace n ON c.relnamespace = n.oid
104            WHERE n.nspname = 'public' AND NOT t.tgisinternal
105            ORDER BY t.tgname
106            LIMIT {} OFFSET {}",
107            pager.limit(),
108            pager.offset(),
109        );
110
111        let rows: Vec<String> = self.connection.fetch_scalar(query.as_str(), database).await?;
112        let (triggers, next_cursor) = pager.finalize(rows);
113
114        Ok(ListTriggersResponse { triggers, next_cursor })
115    }
116}
dbmcp_postgres/tools/list_triggers.rs

dbmcp_postgres/tools/
list_triggers.rs
