Report the failing INSERT when load!() errors (#277)

SQLite3 provides `sqlite3_expanded_sql()` to retrieve the _as-bound_
statement text; this makes it possible to report the exact failing
INSERT when `load!()` fails, e.g. due to a `PRIMARY KEY` violation.

Author: bks-nist

src/SQLite.jl

@@ -17,7 +17,17 @@ const StmtHandle = Ptr{Cvoid} # SQLite3 prepared statement handle
 
 # Normal constructor from filename
 sqliteexception(handle::DBHandle) = SQLiteException(unsafe_string(sqlite3_errmsg(handle)))
+function sqliteexception(handle::DBHandle, stmt::StmtHandle)
+    errstr = unsafe_string(sqlite3_errmsg(handle))
+    stmt_text_handle = sqlite3_expanded_sql(stmt)
+    stmt_text = unsafe_string(stmt_text_handle)
+    msg = "$errstr on statement \"$stmt_text\""
+    sqlite3_free(convert(Ptr{Cvoid}, stmt_text_handle))
+    return SQLiteException(msg)
+end
+
 sqliteerror(handle::DBHandle) = throw(sqliteexception(handle))
+sqliteerror(handle::DBHandle, stmt::StmtHandle) = throw(sqliteexception(handle, stmt))
 
 """
 Internal wrapper that holds the handle to SQLite3 prepared statement.
@@ -158,6 +168,8 @@ mutable struct Stmt <: DBInterface.Statement
     end
 end
 
+sqliteexception(db::DB, stmt::_Stmt) = sqliteexception(db.handle, stmt.handle)
+
 # check if the statement is ready (not finalized due to
 # _close(_Stmt) called and the statment handle removed from DB)
 isready(stmt::Stmt) = haskey(stmt.db.stmts, stmt.id)

src/api.jl

@@ -38,6 +38,12 @@ function sqlite3_prepare16_v2(handle::Ptr{Cvoid}, query::AbstractString, stmt, u
         Cint, (Ptr{Cvoid}, Ptr{UInt16}, Cint, Ptr{Cvoid}, Ptr{Cvoid}),
         handle, query, sizeof(query), stmt, unused)
 end
+function sqlite3_expanded_sql(stmt::Ptr{Cvoid})
+    @NULLCHECK stmt
+    return ccall( (:sqlite3_expanded_sql, libsqlite),
+        Ptr{UInt8}, (Ptr{Cvoid},), stmt)
+end
+sqlite3_free(ptr::Ptr{Cvoid}) = ccall( (:sqlite3_free, libsqlite), Cvoid, (Ptr{Cvoid},), ptr)
 function sqlite3_finalize(stmt::Ptr{Cvoid})
     @NULLCHECK stmt
     return ccall( (:sqlite3_finalize, libsqlite),

src/tables.jl

@@ -252,7 +252,7 @@ function load!(sch::Tables.Schema, rows, db::DB, name::AbstractString, db_tablei
             if r == SQLITE_DONE
                 sqlite3_reset(stmt.handle)
             elseif r != SQLITE_ROW
-                e = sqliteexception(db)
+                e = sqliteexception(db, stmt)
                 sqlite3_reset(stmt.handle)
                 throw(e)
             end