dbmcp_postgres/tools/
list_views.rs

1//! MCP tool: `listViews`.
2
3use dbmcp_server::pagination::{Cursor, Pager};
4
5use super::prelude::*;
6use crate::types::{ListEntriesResponse, ListViewsRequest};
7
8const NAME: &str = "listViews";
9const TITLE: &str = "List Views";
10const DESCRIPTION_PINNED: &str = include_str!("../../assets/tools/list_views/pinned.md");
11const DESCRIPTION_UNPINNED: &str = include_str!("../../assets/tools/list_views/unpinned.md");
12
13fn annotations() -> ToolAnnotations {
14    ToolAnnotations::new()
15        .read_only(true)
16        .destructive(false)
17        .idempotent(true)
18        .open_world(false)
19}
20
21/// Marker type for the `listViews` MCP tool (pinned variant — no `database` field).
22pub(crate) struct PinnedListViewsTool;
23
24impl ToolBase for PinnedListViewsTool {
25    type Parameter = ListViewsRequest;
26    type Output = ListEntriesResponse;
27    type Error = ErrorData;
28
29    fn name() -> Cow<'static, str> {
30        NAME.into()
31    }
32
33    fn title() -> Option<String> {
34        Some(TITLE.into())
35    }
36
37    fn description() -> Option<Cow<'static, str>> {
38        Some(DESCRIPTION_PINNED.into())
39    }
40
41    fn annotations() -> Option<ToolAnnotations> {
42        Some(annotations())
43    }
44
45    fn input_schema() -> Option<Arc<JsonObject>> {
46        Some(input_schema::<Self::Parameter>(true))
47    }
48
49    fn output_schema() -> Option<Arc<JsonObject>> {
50        Some(output_schema::<Self::Output>())
51    }
52}
53
54impl AsyncTool<PostgresHandler> for PinnedListViewsTool {
55    async fn invoke(handler: &PostgresHandler, params: Self::Parameter) -> Result<Self::Output, Self::Error> {
56        handler
57            .list_views(None, params.cursor, params.search, params.detailed)
58            .await
59    }
60}
61
62/// Marker type for the `listViews` MCP tool (unpinned variant — carries `database`).
63pub(crate) struct UnpinnedListViewsTool;
64
65impl ToolBase for UnpinnedListViewsTool {
66    type Parameter = ListViewsRequest;
67    type Output = ListEntriesResponse;
68    type Error = ErrorData;
69
70    fn name() -> Cow<'static, str> {
71        NAME.into()
72    }
73
74    fn title() -> Option<String> {
75        Some(TITLE.into())
76    }
77
78    fn description() -> Option<Cow<'static, str>> {
79        Some(DESCRIPTION_UNPINNED.into())
80    }
81
82    fn annotations() -> Option<ToolAnnotations> {
83        Some(annotations())
84    }
85
86    fn input_schema() -> Option<Arc<JsonObject>> {
87        Some(input_schema::<Self::Parameter>(false))
88    }
89
90    fn output_schema() -> Option<Arc<JsonObject>> {
91        Some(output_schema::<Self::Output>())
92    }
93}
94
95impl AsyncTool<PostgresHandler> for UnpinnedListViewsTool {
96    async fn invoke(handler: &PostgresHandler, params: Self::Parameter) -> Result<Self::Output, Self::Error> {
97        handler
98            .list_views(params.database, params.cursor, params.search, params.detailed)
99            .await
100    }
101}
102
103/// Brief-mode SQL: `pg_views` scan with `ILIKE` filter on view name.
104///
105/// `pg_views` already excludes materialized views (those live in `pg_matviews`),
106/// and `schemaname = 'public'` keeps system-schema views out. The
107/// `($1::text IS NULL OR ...)` trinary lets one statement cover both filtered
108/// and unfiltered cases. View names are unique per schema (Postgres enforces
109/// this), so `viewname` alone is a stable sort key — no tiebreaker needed.
110const BRIEF_SQL: &str = r"
111    SELECT viewname
112    FROM pg_views
113    WHERE schemaname = 'public'
114      AND ($1::text IS NULL OR viewname ILIKE '%' || $1 || '%')
115    ORDER BY viewname
116    LIMIT $2 OFFSET $3";
117
118/// Detailed-mode SQL: per-view `json_build_object` projection.
119///
120/// `pg_views` excludes materialized views. The `pg_namespace` + `pg_class`
121/// joins anchor the relation OID needed by `obj_description`. Postgres defers
122/// SELECT-list evaluation past `LIMIT`, so `obj_description` only runs for the
123/// page's rows — never the full schema. `pg_views.viewowner` is already a role
124/// name, so no `pg_roles` join is needed. View names are unique per schema, so
125/// `viewname` alone is a stable sort key.
126const DETAILED_SQL: &str = r"
127    SELECT
128        v.viewname AS name,
129        json_build_object(
130            'schema',      v.schemaname,
131            'owner',       v.viewowner,
132            'description', pg_catalog.obj_description(c.oid, 'pg_class'),
133            'definition',  v.definition
134        ) AS entry
135    FROM pg_views v
136    JOIN pg_namespace n ON n.nspname = v.schemaname
137    JOIN pg_class     c ON c.relname = v.viewname AND c.relnamespace = n.oid
138    WHERE v.schemaname = 'public'
139      AND ($1::text IS NULL OR v.viewname ILIKE '%' || $1 || '%')
140    ORDER BY v.viewname
141    LIMIT $2 OFFSET $3";
142
143impl PostgresHandler {
144    /// Lists one page of user-defined views, optionally filtered and/or detailed.
145    ///
146    /// # Errors
147    ///
148    /// Returns [`ErrorData`] with code `-32602` if `cursor` is malformed,
149    /// or an internal-error [`ErrorData`] if `database` is invalid
150    /// or the underlying query fails.
151    pub async fn list_views(
152        &self,
153        database: Option<String>,
154        cursor: Option<Cursor>,
155        search: Option<String>,
156        detailed: bool,
157    ) -> Result<ListEntriesResponse, ErrorData> {
158        let database = database.as_deref().map(str::trim).filter(|s| !s.is_empty());
159        let pattern = search.as_deref().map(str::trim).filter(|s| !s.is_empty());
160        let pager = Pager::new(cursor, self.config.page_size);
161
162        if detailed {
163            let rows: Vec<(String, sqlx::types::Json<serde_json::Value>)> = self
164                .connection
165                .fetch(
166                    sqlx::query(DETAILED_SQL)
167                        .bind(pattern)
168                        .bind(pager.limit())
169                        .bind(pager.offset()),
170                    database,
171                )
172                .await?;
173            let (rows, next_cursor) = pager.paginate(rows);
174            return Ok(ListEntriesResponse::detailed(
175                rows.into_iter().map(|(key, json)| (key, json.0)).collect(),
176                next_cursor,
177            ));
178        }
179
180        let rows: Vec<String> = self
181            .connection
182            .fetch_scalar(
183                sqlx::query(BRIEF_SQL)
184                    .bind(pattern)
185                    .bind(pager.limit())
186                    .bind(pager.offset()),
187                database,
188            )
189            .await?;
190        let (views, next_cursor) = pager.paginate(rows);
191        Ok(ListEntriesResponse::brief(views, next_cursor))
192    }
193}
dbmcp_postgres/tools/list_views.rs

dbmcp_postgres/tools/
list_views.rs
