> For the complete documentation index, see [llms.txt](https://docs.squidex.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.squidex.io/id-02-documentation/concepts/schemas/field-rules.md).
# Field Rules
This documentation is based on the *FoodCrunch* use case. Please open the link below alongside this page to understand the examples.
{% content-ref url="/pages/-MSTfiNBwo8C1m-UB3WL" %}
[Introduction and Use Case](/id-02-documentation/introduction-and-use-case.md)
{% endcontent-ref %}
A Field Rule is a method of implementing automated actions on schema fields when a certain condition is met. It is made up of three components as follows:
* **Action**: This component states what should be done when the condition(s) is/are met. It has the following options:
* Disable
* Hide
* Require
* **Field**: This relates to when the schema field is selected dependent upon which action should be taken.
* **Condition**: Written in Javascript, this action is triggered when the condition is met.
For our *FoodCrunch* user case let's consider the following example to understand Field Rules. For all startups that are not in `Pre-Seed` stage, the funding value must be mentioned. It is therefore a required field.
For our use case, the rule is that anytime the value of the **Stage** field is anything other than `Pre-Seed`, then the **Funding** is a required field, otherwise it's optional.
Let's see how to implement this:
* Ensure that the **Validation** (2) of the **Stage** (1) field is set to **Required** (3) in the settings. This is necessary to make sure that a value is always selected.
Setting validation for a field
* To create a Field Rule, go to the **Schema** (1) (i.e. in our case `startups`), select the **More** (2) tab, click **+** (3) under Field Rules and enter the selections for **Action, Field and Condition** (4). Click **Save** (5) when done.\
\
In our example the following values have been set:
1. Action = `Require`
2. Field = `funding`
3. Condition (in Javascript) = `data.stage.iv != 'Pre-Seed'`
Creating a Field Rule
* This can now be validated by trying to add content. Go to **Content** and try adding content. Immediately you will find that the stage and funding fields have a red flag.
Fields with rules
* If you set **stage** as `Pre-Seed`, the red flag denoting that the **funding** value is required will disappear, which means its optional.
Rule validation example 1
* If you set **stage** as any other value, the red flag remains meaning that a value has to be entered in **funding**.