---
title: Prevent duplicate submission
summary: Block a user from submitting the same form twice via rapid repeated clicks.
status: draft
owner: SAIF Doc Gen
last_reviewed: 2026-08-17
library: SAIF.Presentation.Web.Controls.V2
reference_type: package
operation_id: OP-V2-009
trigger: "`OnLoad` and `Render` for a `OneClickSubmit` button instance; client click for the guard script."
---

# Prevent duplicate submission

Block a user from submitting the same form twice via rapid repeated clicks. `OnLoad` and `Render` for a `OneClickSubmit` button instance; client click for the guard script.

| Field | Value |
| --- | --- |
| **Operation ID** | OP-V2-009 |
| **Trigger** | `OnLoad` and `Render` for a `OneClickSubmit` button instance; client click for the guard script. |
| **Inputs** | `CssClass` (optional). |
| **Outputs** | A submit button whose client click is guarded against duplicate submission. |
| **Primary components** | `OneClickSubmit` |
| **Entry point** | `SAIF.Presentation.Web.Controls.V2/OneClickSubmitControl.vb` |

## Steps

1. On `OnLoad`, set `OnClientClick` to `return OneClickOnly()`. ([BR-V2-058](../business-rules.md#br-v2-058-one-click-submit-always-guards-the-client-click))
2. Register the `WasClicked` flag variable script block and the `OneClickOnly()` function script block on the page, each only once. ([BR-V2-059](../business-rules.md#br-v2-059-duplicate-click-guard-script-registered-once-per-page))
3. On `Render`, apply the default CSS class `NormalButton` when no CSS class has been set, then delegate to the base button rendering. ([BR-V2-060](../business-rules.md#br-v2-060-default-css-class-is-normalbutton))

## Process flow

The following diagram visualizes this operation's control flow.

```mermaid
flowchart TD
	Start([OnLoad]) --> Client["Set OnClientClick=return OneClickOnly()"]
	Client --> Reg["Register WasClicked flag + OneClickOnly function once"]
	Reg --> RenderS([Render]) 
	RenderS --> Css{CssClass set?}
	Css -->|No| Default[Apply NormalButton]
	Css -->|Yes| Base[MyBase.Render]
	Default --> Base
	Base --> Done([Rendered])
```

## Failure and edge-case behavior

- No exceptional failure handling beyond the branches described in **Steps** was found in the analysis findings.*

## Related documentation
- [Operations and processes](../operations-processes.md)
- [Business rules](../business-rules.md)

## Sources
- `SAIF.Presentation.Web.Controls.V2/OneClickSubmitControl.vb`