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GetFID

Function GetFID( const aTable, aName : string) : TGuid

Example​

procedure ScriptEvent(var Value: variant);
var
  ModuleFID: TGuid;
begin
  // Prefer a typed wrapper when one exists. The table name is trusted code.
  ModuleFID := GetFID('VX_MAP', 'Daily Import');
  Value := GUIDToStringNoBraces(ModuleFID);
end;

Usage​

GetFID resolves a named module row in a caller-specified Velox configuration table to its FID.

Parameters and result

ItemTypeDescription
aTablestring, constTable expression interpolated directly into the SQL statement. It must be a trusted, valid Velox configuration table identifier.
aNamestring, constMODULENAME to find. SQLString converts it to an SQL literal by removing embedded NUL characters and doubling apostrophes.
ResultTGuidThe first matching FID, or the all-zero EmptyGuid sentinel if the query returns no row.

Security boundary

aName is treated as data, but aTable is inserted into the SQL statement as executable syntax. Never pass user input, message data or other untrusted text as aTable. An attacker-controlled value can alter the query. Prefer the module-specific FID lookup functions where available; call GetFID directly only with a fixed table identifier controlled by the script author.

Additional Technical Info​

GetFID searches a Velox system/configuration table for a row whose MODULENAME equals aName, then returns that row's binary TGuid FID. It is the shared implementation behind functions such as GetMapFID, GetActionFID and GetVariableFID.

The table and module name in the example are source-reviewed but fictional; the documentation workflow did not execute the query. Prefer a fixed-table wrapper such as GetMapFID because aTable becomes an SQL identifier without validation or quoting.

Implementation

The scripting import registers the public function against the Velox FID helper. The implementation:

  1. obtains a new query from gSystemConnection.SQLC;
  2. builds select FID from <aTable> where MODULENAME = <SQLString(aName)>;
  3. opens the query;
  4. reads Fields[0].AsGuid when the cursor is not at end-of-file, otherwise returns EmptyGuid; and
  5. closes and frees the query in a finally block.

There is no cache, table allow-list, uniqueness check or order by clause.

Behaviour and edge cases

  • Name matching, case sensitivity, trailing-space treatment and character collation come from the configuration database.
  • SQLString removes every embedded #0 from aName. Names that differ only by NUL characters therefore collapse to the same lookup text; this conversion is lossy.
  • The query has no order by. If corrupt or custom data contains duplicate matching names, which row is returned is database-dependent.
  • A missing row and a stored all-zero FID are indistinguishable. Test the result with IsEmptyGuid.
  • An empty name is still queried as an empty SQL string; it is not rejected before database access.
  • The function does not confirm that aTable has the expected columns or that the resolved object is enabled, usable or of the intended semantic type.
  • The result reflects the database and transaction state at execution time. A rename, deletion or replacement can change later calls.

Side effects and errors

This is a read-only database operation, but it allocates a query and uses the shared system connection. Invalid table syntax, missing tables or columns, database availability and permission failures, SQL execution errors and invalid GUID field data propagate as exceptions. Only a successfully executed query with no returned row becomes EmptyGuid.

Performance and concurrency

Every call performs a live query. Resolve a stable name once outside record-level loops and reuse the TGuid. The query object is always freed, while connection pooling, transaction visibility, locking and concurrent configuration changes are governed by gSystemConnection and the database.

Related entries

Created 2026-07-15