This page is for admins who make Buttons. Advanced validation examines the fields of a Workflow button with rules before OneClick sends the data. A rule can require a value, a number range, a date range or a text format. When the fields do not agree with the rules, OneClick does not send the data. The user sees your error messages and can correct the values. Advanced validation is part of the **Custom Fields** section. First add the fields. See [Custom fields](/docs/buttons/workflow-button/sections/custom-fields). ![The Validation tab of the Button Create invoice: an AND group with the rules Value greater than 1000 and Invoice reference not empty, with error messages](https://res.cloudinary.com/zimple/image/upload/f_auto,q_auto/oneclick-docs/buttons/workflow-button/sections/advanced-validation/validation-tab.png) ## Turn on Advanced validation 1. Open the Button in the Button editor. 2. Click **Custom Fields** in the menu. 3. Add the fields that you want to examine on the **Fields** tab. 4. Turn on **Advanced validation** above **Add new data field**. The **Validation** tab shows a green check mark. 5. Click the **Validation** tab. 6. Add the rules. See [Add a rule](#add-a-rule). 7. Click **Save**. When **Advanced validation** is on, all rules of the Button are on the **Validation** tab. The fields have no **Required** and **Do not allow value** check boxes, and OneClick ignores their old values. **Hidden** stays on the **Fields** tab. ## Add a rule A rule examines the value of one field. The **Validation** tab starts with one group. Each group has buttons to add rules and groups. 1. Click **+ Rule** in the group. A rule shows in the group. 2. Select the field in the first list. 3. Select the type of the rule in the second list, for example **greater than**. 4. Type the value of the rule, for example `100`. Some rule types, such as **empty** or **this month**, have no value. A field can have more than one rule. To remove a rule, click the bin icon at the right of the rule. To move a rule up or down, click the arrows. ### Rule types The rule types depend on the type of the field: | Field type | Rule types | | ---------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------- | | Text, email, phone, address, person and organization | **begins with**, **contains**, **does not begin with**, **does not contain**, **does not end with**, **ends with**, **empty**, **not empty**, **regex** | | Number and monetary | **equal**, **not equal**, **less than**, **greater than**, **less than or equal**, **greater than or equal**, **between**, **not between**, **empty**, **not empty** | | Date | The number rule types, and **this day**, **this month**, **last month**, **next month**, **this quarter**, **last quarter**, **next quarter**, **this year**, **last year**, **next year**, **last 7 days**, **next 7 days**, **last 30 days**, **next 30 days** | | Single option, multiple options and users | **in**, **not in**, **empty**, **not empty** | | Boolean | **equal** | ### Regular expressions A **regex** rule examines a text with a regular expression. OneClick uses JavaScript regular expressions. For example, `^[0-9]{5,7}$` accepts 5 to 7 digits. Test the expression before you save the Button, for example on [regex101.com](https://regex101.com/) with the flavor **ECMAScript (JavaScript)**. ## Rule groups A group joins its rules with **AND** or **OR**. Select it in the list at the left of the group: - **AND**: all rules of the group must pass. - **OR**: at least one rule of the group must pass. To add a group in a group, click **+ Group**. A group in a group counts as one rule of its parent group. Thus you can make conditions such as "A and (B or C)". You can put groups in groups to a maximum of three levels below the first group. To remove a group, click the bin icon at the right of the group. When you save, each group must contain at least one rule or group. Else OneClick shows **The group must contain at least one field**. If a rule has no value, OneClick shows **Validation builder schema is invalid**. ## Error messages Write error messages that tell the user what to correct. You can write a message for a rule and for a group. - **Rule message:** click the arrow at the right of the rule value. Type the message in **Add error message**. Only the rules in the first group have a rule message. - **Group message:** type the message in **Add error message for group** in the group header. A rule message shows below its field. A group message shows above the fields. When two groups in the same parent group fail, OneClick joins their messages with "AND" or "OR", as the parent group does. If a failed rule has no message, OneClick writes a message from the rule, for example **is empty** or **does not match regex pattern** with the expression. If a group in a group fails and no group has a message, the user sees **Validation failed**. For the view of the user, see [Required fields and errors](/docs/use-buttons/fill-in-fields#required-fields-and-errors). ## Hidden fields with rules A field can be hidden and have rules. The user then sees the field only when it is not valid. If all fields are valid, the user does not see the fields, and OneClick sends the data. See [A Button with hidden fields](/docs/use-buttons/fill-in-fields#a-button-with-hidden-fields). ## Example: an invoice by email or by post A Button sends an invoice for a deal. The invoice goes by email or by post. Before OneClick sends the data, the organization must have: - A VAT number of two letters and at least six digits, for example `GB123456`. - An invoicing email address, or a full postal address with a postal code of 5 to 7 digits. This example uses the organization fields **VAT number**, **Invoicing email**, **Street**, **Postal code** and **City**. Use the fields of your Pipedrive company. ### Add the fields 1. On the **Fields** tab, add the five organization fields. 2. Select **Hidden** for each field. The user then sees a field only when it is not valid. 3. Turn on **Advanced validation**. ### Make the groups and rules Make these groups and rules on the **Validation** tab: ``` AND ├── VAT number regex ^[A-Za-z]{2}[0-9]{6,}$ └── OR ├── AND │ └── Invoicing email contains @ └── AND ├── Street not empty ├── Postal code regex ^[0-9]{5,7}$ └── City not empty ``` 1. In the first group, select **AND**. 2. Click **+ Rule**. Select **VAT number**, **regex** and type `^[A-Za-z]{2}[0-9]{6,}$`. 3. Click **+ Group**. Select **OR** in the new group. 4. In the **OR** group, click **+ Group** two times. Select **AND** in the two new groups. 5. In the first **AND** group, add the rule **Invoicing email**, **contains**, `@`. 6. In the second **AND** group, add the rules **Street**, **not empty**; **Postal code**, **regex**, `^[0-9]{5,7}$`; and **City**, **not empty**. The validation passes when the VAT number is correct, and the email or the full address is correct. ### Add the error messages 1. At the VAT number rule, click the arrow and type `VAT number is not valid` in **Add error message**. 2. In the **OR** group, type `Add an invoicing email or a postal address` in **Add error message for group**. 3. In the email group, type `Invoicing email is not valid`. 4. In the address group, type `Postal address is missing or not valid`. 5. Click **Save**. The first group needs no message. The messages of the rule and of the groups below it tell the user what is wrong. ### The result The user clicks the Button on a deal of the organization. The organization has no VAT number, no email and no postal code. OneClick does not send the data. It shows the VAT number field with **VAT number is not valid**, and the messages of the groups above the fields. When all values are correct, OneClick sends the data. The user does not see the hidden fields.