---
title: "Prepopulating or Prefilling Forms Using Query String Parameters"
slug: "prepopulating-or-prefilling-forms-using-query-string-parameters"
updated: 2026-08-24T13:56:16Z
published: 2026-08-24T13:56:16Z
canonical: "knowledge.technolutions.net/prepopulating-or-prefilling-forms-using-query-string-parameters"
---
> ## Documentation Index
> Fetch the complete documentation index at: https://knowledge.technolutions.net/llms.txt
> Use this file to discover all available pages before exploring further.
# Prepopulating or Prefilling Forms Using Query String Parameters
A **query string parameter** uses the content of a URL to pass information to a webpage. The information is contained in a *parameter* and its *value*. They follow a `?` at the end of the URL path. For example: `https://example.com/path/to/page?name=ferret&color=purple`
- The query string begins after `?`
- The parameters are `name` and `color`
- The values are `ferret` and `purple`
- The `&` chains multiple parameters together
## Query string parameters in Slate
In Slate, query string parameters can do things like:
- Tell a form which person record is filling it out
- Pre-populate form fields, like an academic interest
## For a Record
You can use person record parameter’s with that record's unique identifier to pre-fill system fields on a form. The record is updated upon submission of the form.
> [!WARNING]
> 📝 Parameters must be in all lowercase. Values can contain uppercase letters.
| Form Scope | Configurable Joins Export to Use | Example URL |
| --- | --- | --- |
| Person | GUID from the Person Query Base | `www.slateuniversity.org/register/moreinfo?person={{Person-GUID}}` |
| Application | GUID from the Application Query Base | `www.slateuniversity.org/register/admitstudentday?person={{Application-GUID}}` |
| Dataset | GUID from the Dataset's Query Base | `www.slateuniversity.org/register/counselorinfo?person={{Organization-Contact-GUID}}` |
If your URL already includes a query string parameter, you must append this additional parameter with an ampersand `&` instead of a question mark `?`.
For instance:
- We would append `www.slateuniversity.org/register/moreinfo` with `?person={{Person-GUID}}`
- While, on the other hand, we would append `www.slateuniversity.org/register/?id=48125437-447b-4638-925b-5ee8b09808cf` with `&person={{Person-GUID}}`
## In a mailing
If a query string parameter uses a merge field in a mailing, that merge field must:
- Be included as an export in the mailing's recipient list
- Match the export's Name setting. If the export's Name setting has spaces, the merge field will replace those spaces with dashes `-`. For instance, "Academic Program" would become `{{Academic-Program}}`
## For a Form Field
Slate can prepopulate a form field using a parameter and a value. The parameter will be the form field's Export Key (e.g., `sys:first`, `sys:field:acainterest`).
The value being passed in, however, must respect the form field type being used:
| Form Field Type | Is the Field Mapped? | Acceptable Value | Example |
| --- | --- | --- | --- |
| Prompt Driven | Yes | The prompt's GUID | `www.slateuniversity.org/register/moreinfo?sys:field:acainterest=84fcea7a-72e6-4743-8594-4c25c1c25015` |
| Prompt Driven | No | The prompt's exact value | `www.slateuniversity.org/register/campusvisit?lunch_preference=Chicken` |
| Free Response | N/A | A string | `www.slateuniversity.org/register/moreinfo?sys:first=Alexander&sys:last=Hamilton` |
A prompt's GUID is visible when accessing that prompt in the prompts tool:
[](https://cdn.us.document360.io/cd8ea7a6-07f3-4846-a554-627ac016d3e3/Images/Documentation/guid.png)
It is possible to concurrently pre-populate:
- Multiple form fields
- A form field with multiple values
## Embedded Forms
If you wanted to prefill a program of interest form field with an Export Key of `sys:field:acainterest` and a value of "Computer Science" (using the example prompt above), the embed code would be something like:
```xml
Loading...
```
📖 [Embedding forms](/v1/docs/embedding-forms)