dbmcp_postgres/tools/
list_materialized_views.rs

1//! MCP tool: `listMaterializedViews`.
2
3use std::borrow::Cow;
4
5use dbmcp_server::pagination::Pager;
6use dbmcp_sql::Connection as _;
7use rmcp::handler::server::router::tool::{AsyncTool, ToolBase};
8use rmcp::model::{ErrorData, ToolAnnotations};
9
10use crate::PostgresHandler;
11use crate::types::{ListMaterializedViewsRequest, ListMaterializedViewsResponse};
12
13/// Marker type for the `listMaterializedViews` MCP tool.
14pub(crate) struct ListMaterializedViewsTool;
15
16impl ListMaterializedViewsTool {
17    const NAME: &'static str = "listMaterializedViews";
18    const TITLE: &'static str = "List Materialized Views";
19    const DESCRIPTION: &'static str = include_str!("../../assets/tools/list_materialized_views.md");
20}
21
22impl ToolBase for ListMaterializedViewsTool {
23    type Parameter = ListMaterializedViewsRequest;
24    type Output = ListMaterializedViewsResponse;
25    type Error = ErrorData;
26
27    fn name() -> Cow<'static, str> {
28        Self::NAME.into()
29    }
30
31    fn title() -> Option<String> {
32        Some(Self::TITLE.into())
33    }
34
35    fn description() -> Option<Cow<'static, str>> {
36        Some(Self::DESCRIPTION.into())
37    }
38
39    fn annotations() -> Option<ToolAnnotations> {
40        Some(
41            ToolAnnotations::new()
42                .read_only(true)
43                .destructive(false)
44                .idempotent(true)
45                .open_world(false),
46        )
47    }
48}
49
50impl AsyncTool<PostgresHandler> for ListMaterializedViewsTool {
51    async fn invoke(handler: &PostgresHandler, params: Self::Parameter) -> Result<Self::Output, Self::Error> {
52        handler.list_materialized_views(params).await
53    }
54}
55
56/// Brief-mode SQL: `pg_matviews` scan with `ILIKE` filter on matview name.
57///
58/// `pg_matviews` already filters to `pg_class.relkind = 'm'`, and
59/// `schemaname = 'public'` keeps system-schema matviews out. The
60/// `($1::text IS NULL OR ...)` trinary lets one statement cover both filtered
61/// and unfiltered cases. Matview names are unique per schema (Postgres enforces
62/// this via `pg_class`'s unique index on `(relname, relnamespace)`), so
63/// `matviewname` alone is a stable sort key — no tiebreaker needed.
64const BRIEF_SQL: &str = r"
65    SELECT matviewname
66    FROM pg_matviews
67    WHERE schemaname = 'public'
68      AND ($1::text IS NULL OR matviewname ILIKE '%' || $1 || '%')
69    ORDER BY matviewname
70    LIMIT $2 OFFSET $3";
71
72/// Detailed-mode SQL: per-matview `json_build_object` projection.
73///
74/// `pg_matviews` already filters to `relkind = 'm'`. The `pg_namespace` +
75/// `pg_class` joins anchor the relation OID needed by `obj_description`.
76/// Postgres defers SELECT-list evaluation past `LIMIT`, so `obj_description`
77/// only runs for the page's rows — never the full schema.
78/// `pg_matviews.matviewowner` is already a role name, so no `pg_roles` join is
79/// needed. `populated` and `indexed` are projected directly from
80/// `pg_matviews.ispopulated` / `pg_matviews.hasindexes`. Matview names are
81/// unique per schema, so `matviewname` alone is a stable sort key.
82const DETAILED_SQL: &str = r"
83    SELECT
84        mv.matviewname AS name,
85        json_build_object(
86            'schema',      mv.schemaname,
87            'owner',       mv.matviewowner,
88            'description', pg_catalog.obj_description(c.oid, 'pg_class'),
89            'definition',  mv.definition,
90            'populated',   mv.ispopulated,
91            'indexed',     mv.hasindexes
92        ) AS entry
93    FROM pg_matviews mv
94    JOIN pg_namespace n ON n.nspname = mv.schemaname
95    JOIN pg_class     c ON c.relname = mv.matviewname AND c.relnamespace = n.oid
96    WHERE mv.schemaname = 'public'
97      AND ($1::text IS NULL OR mv.matviewname ILIKE '%' || $1 || '%')
98    ORDER BY mv.matviewname
99    LIMIT $2 OFFSET $3";
100
101impl PostgresHandler {
102    /// Lists one page of user-defined materialized views, optionally filtered and/or detailed.
103    ///
104    /// # Errors
105    ///
106    /// Returns [`ErrorData`] with code `-32602` if `cursor` is malformed,
107    /// or an internal-error [`ErrorData`] if `database` is invalid
108    /// or the underlying query fails.
109    pub async fn list_materialized_views(
110        &self,
111        ListMaterializedViewsRequest {
112            database,
113            cursor,
114            search,
115            detailed,
116        }: ListMaterializedViewsRequest,
117    ) -> Result<ListMaterializedViewsResponse, ErrorData> {
118        let database = database.as_deref().map(str::trim).filter(|s| !s.is_empty());
119        let pattern = search.as_deref().map(str::trim).filter(|s| !s.is_empty());
120        let pager = Pager::new(cursor, self.config.page_size);
121
122        if detailed {
123            let rows: Vec<(String, sqlx::types::Json<serde_json::Value>)> = self
124                .connection
125                .fetch(
126                    sqlx::query(DETAILED_SQL)
127                        .bind(pattern)
128                        .bind(pager.limit())
129                        .bind(pager.offset()),
130                    database,
131                )
132                .await?;
133            let (rows, next_cursor) = pager.paginate(rows);
134            return Ok(ListMaterializedViewsResponse::detailed(
135                rows.into_iter().map(|(key, json)| (key, json.0)).collect(),
136                next_cursor,
137            ));
138        }
139
140        let rows: Vec<String> = self
141            .connection
142            .fetch_scalar(
143                sqlx::query(BRIEF_SQL)
144                    .bind(pattern)
145                    .bind(pager.limit())
146                    .bind(pager.offset()),
147                database,
148            )
149            .await?;
150        let (materialized_views, next_cursor) = pager.paginate(rows);
151        Ok(ListMaterializedViewsResponse::brief(materialized_views, next_cursor))
152    }
153}
dbmcp_postgres/tools/list_materialized_views.rs

dbmcp_postgres/tools/
list_materialized_views.rs
