Merge pull request #15 from database-playground/pan93412/dbp-61-implement-database-structure-retrieval

DBP-61: implement database structure retrieval

Author: pan93412

graph/database.graphqls

@@ -0,0 +1,12 @@
+extend type Database {
+    structure: DatabaseStructure!
+}
+
+type DatabaseStructure {
+    tables: [DatabaseTable!]!
+}
+
+type DatabaseTable {
+    name: String!
+    columns: [String!]!
+}

graph/database.resolvers.go

@@ -64,10 +64,15 @@ extend type Question {
   referenceAnswerResult: SQLExecutionResult! @scope(scope: "question:read")
 
   """
-  List of your submissions for this question.
+  List of your submissions for this question, ordered by submitted at descending.
   """
   userSubmissions: [Submission!]!
 
+  """
+  Get the last submission for this question.
+  """
+  lastSubmission: Submission
+
   """
   Have you tried to solve the question?
   """

graph/ent.resolvers.go

@@ -45,3 +45,14 @@ type ErrorResponse struct {
 func (e ErrorResponse) Error() string {
 	return fmt.Sprintf("%s: %s", e.Code, e.Message)
 }
+
+// DatabaseStructure is the database structure of a schema.
+type DatabaseStructure struct {
+	Tables []DatabaseTable `json:"tables"`
+}
+
+// DatabaseTable is the table structure of a schema.
+type DatabaseTable struct {
+	Name    string   `json:"name"`
+	Columns []string `json:"columns"`
+}

graph/event.resolvers.go

@@ -66,6 +66,50 @@ func (s *SqlRunner) Query(ctx context.Context, schema, query string) (DataRespon
 	return respBody.Data, nil
 }
 
+func (s *SqlRunner) GetDatabaseStructure(ctx context.Context, schema string) (DatabaseStructure, error) {
+	// Query SQLite's master table to get all table names
+	tablesQuery := "SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%' ORDER BY name"
+	tablesResp, err := s.Query(ctx, schema, tablesQuery)
+	if err != nil {
+		return DatabaseStructure{}, fmt.Errorf("failed to query tables: %w", err)
+	}
+
+	var tables []DatabaseTable
+
+	// For each table, get its column information
+	for _, row := range tablesResp.Rows {
+		if len(row) == 0 {
+			continue
+		}
+		tableName := row[0]
+
+		// Use PRAGMA table_info to get column information
+		columnsQuery := fmt.Sprintf("PRAGMA table_info(%s)", tableName)
+		columnsResp, err := s.Query(ctx, schema, columnsQuery)
+		if err != nil {
+			return DatabaseStructure{}, fmt.Errorf("query columns for table %s: %w", tableName, err)
+		}
+
+		var columns []string
+		// PRAGMA table_info returns: cid, name, type, notnull, dflt_value, pk
+		// We only need the name (index 1)
+		for _, columnRow := range columnsResp.Rows {
+			if len(columnRow) > 1 {
+				columns = append(columns, columnRow[1])
+			}
+		}
+
+		tables = append(tables, DatabaseTable{
+			Name:    tableName,
+			Columns: columns,
+		})
+	}
+
+	return DatabaseStructure{
+		Tables: tables,
+	}, nil
+}
+
 func (s *SqlRunner) IsHealthy(ctx context.Context) bool {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fmt.Sprintf("%s/healthz", s.cfg.URI), nil)
 	if err != nil {