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Correct the Type Diagram Content #190

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daf6a7d
Add type diagram content
samithkavishke Apr 28, 2026
6afb42e
Resolve coderabbit suggestions
samithkavishke Apr 28, 2026
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257 changes: 218 additions & 39 deletions en/docs/develop/integration-artifacts/supporting/types.md
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
---
title: Types
description: Define shared data structures with record types, enums, union types, and table types for type-safe integrations.
description: Define shared data structures with record, enum, service class, union, and array types for type-safe integrations.
---

import Tabs from '@theme/Tabs';
Expand All @@ -10,6 +10,8 @@ import TabItem from '@theme/TabItem';

Type artifacts define the data structures used throughout your integration. They ensure type safety across services, event handlers, and transformations. Define types in dedicated `.bal` files and reuse them across all artifacts in your project.

The visual designer exposes five type kinds: **Record**, **Enum**, **Service Class**, **Union**, and **Array**. Each kind maps to a Ballerina type definition in source.

## Adding a type

<Tabs>
Expand All @@ -21,16 +23,16 @@ Type artifacts define the data structures used throughout your integration. They

2. Click **+** next to **Types** in the sidebar (or click **+ Add Type** from the Types canvas).

3. In the **New Type** panel, choose **Create from scratch** or **Import**.
3. In the **New Type** panel, choose **Create from scratch** or **Import** to bring in an existing definition.

![New Type creation form showing Kind and Name fields](/img/develop/integration-artifacts/supporting/types/step-2.png)

| Field | Description |
|---|---|
| **Kind** | The type kind: **Record**, **Enum**, **Union**, or **Table**. |
| **Kind** | The type kind: **Record**, **Enum**, **Service Class**, **Union**, or **Array**. |
| **Name** | A unique name for the type (for example, `OrderRequest`). |
| **Fields** | For records — add fields using the **+** button. Each field has a name and a type. |
| **Advanced Options** | Expand to set additional constraints such as closed record enforcement. |
| **Members / Fields / Resource Methods** | The structural members for the selected kind. The label changes to match the kind. |
| **Advanced Options** | Per-kind options such as **Allow Additional Fields**, **Is Readonly Type**, and **Accessible by Other Integrations**. |

4. Click **Save**. The type is added to your project and appears in the type diagram.

Expand Down Expand Up @@ -95,64 +97,227 @@ type OrderRequest record {|

## Type kinds

### Records
### Record

A record defines a structured type with named fields.

<Tabs>
<TabItem value="ui" label="Visual Designer" default>

Select **Record** from the **Kind** dropdown to define a structured type with named fields. Use **Advanced Options** to enforce a closed record (no extra fields allowed).
Select **Record** from the **Kind** dropdown, then add one row per field using **+**.

For each field:

| Control | Description |
|---|---|
| **Name** | The field name. |
| **Type** | The field type (built-in, user-defined, or another record). |
| **Inline record** (`{}`) | Define the field's type as a nested record inline, instead of referencing an existing type. |
| **Optional** (`?`) | Mark the field optional. The field becomes `T?` and may be absent at runtime. |
| **Delete** (trash) | Remove the field. |

Expand a field row to set:

| Option | Description |
|---|---|
| **Default Value** | A literal expression assigned when the field is omitted. The field is then defaultable in source. |
| **Description** | Documentation for the field, emitted as a Ballerina doc comment. |
| **Readonly** | Mark this field immutable. The field becomes `readonly T`. |

**Advanced Options**:

| Option | Description |
|---|---|
| **Allow Additional Fields** | Generate an open record (`record { ... }`) that accepts unknown fields. Leave unchecked for a closed record (`record {\| ... \|}`). |
| **Is Readonly Type** | Wrap the whole type as `readonly & T` so every field is immutable. |
| **Accessible by Other Integrations** | Add the `public` qualifier so the type can be imported from other packages. |

</TabItem>
<TabItem value="code" label="Ballerina Code">

```ballerina
// Closed record — no extra fields permitted
type OrderRequest record {|
string customerId;
# Represents an order placed by a customer.
public type OrderRequest record {|
# Unique identifier of the customer.
readonly string customerId;
LineItem[] items;
Address shippingAddress;
# Optional discount coupon.
string? couponCode;
string currency = "USD";
|};
```

</TabItem>
</Tabs>

### Enums
### Enum

An enum defines a fixed set of named string values.

<Tabs>
<TabItem value="ui" label="Visual Designer" default>

Select **Enum** from the **Kind** dropdown to define a fixed set of string values. Add each member value using the **+** button in the **Members** section.
Select **Enum** from the **Kind** dropdown, then add each member using **+**.

For each member:

| Control | Description |
|---|---|
| **Enum member name** | The member identifier (for example, `PENDING`). |
| **Constant Expression** | The string value bound to the member. Leave empty to use the member name as the value. |

</TabItem>
<TabItem value="code" label="Ballerina Code">

```ballerina
enum OrderStatus {
PENDING,
CONFIRMED,
SHIPPED,
DELIVERED,
CONFIRMED = "confirmed",
SHIPPED = "shipped",
DELIVERED = "delivered",
CANCELLED
}
```

</TabItem>
</Tabs>

### Unions
### Service class

A service class defines an object that exposes resource methods, used to model dynamically generated services such as GraphQL resolvers.

<Tabs>
<TabItem value="ui" label="Visual Designer" default>

Select **Union** from the **Kind** dropdown to allow a value to be one of several types. Add each member type using the **+** button.
#### Create a service class

Select **Service Class** from the **Kind** dropdown, then add one row per resource method using **+**.

For each resource method:

| Control | Description |
|---|---|
| **Name** | The resource path/name (for example, `name1`). |
| **Type** | The return type of the resource method. |
| **+ Add Parameter** | Add an input parameter. Each parameter takes a **Parameter Name**, **Parameter Type**, and an optional **Default Value**. |
| **Delete** (trash) | Remove the resource method. |

#### Edit the service class

The editing experience for a service class differs from other kinds. Click **Edit** on the type to open the **Edit Type: Service Class** panel:

| Control | Description |
|---|---|
| **Object Name** | Rename the service class. |
| **Description** | Free-text documentation rendered as a Ballerina doc comment. |
| **Fields** | List of resource methods. Use **+** to add, the pencil icon to edit a field, or the trash icon to remove it. |
| **Implement** | Switch to the **Service Class Designer** to add class variables and write method bodies. |

#### Edit a field

Click the pencil icon on a field to open the **Edit Field** panel:

| Control | Description |
|---|---|
| **Field Name** | The resource path/name. |
| **Description** | Documentation for the field. |
| **Arguments** | Use **+ Add Argument** to define input parameters for the resource method. |
| **Field Type** | The return type (for example, `string\|error`). |

Comment on lines +223 to +227
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⚠️ Potential issue | 🟡 Minor

🧩 Analysis chain

🏁 Script executed:

# Check if the file exists and examine the content around lines 223-227
if [ -f "en/docs/develop/integration-artifacts/supporting/types.md" ]; then
  echo "=== File found. Content at lines 223-227 ==="
  sed -n '223,227p' "en/docs/develop/integration-artifacts/supporting/types.md" | cat -n
  echo ""
  echo "=== Broader context (lines 215-235) ==="
  sed -n '215,235p' "en/docs/develop/integration-artifacts/supporting/types.md" | cat -n
else
  echo "File not found at expected path"
fi

Repository: wso2/docs-integrator

Length of output: 1483

🏁 Script executed:

# Search for similar escape patterns with pipes in this file
echo "=== Searching for backslash-escaped pipes in the file ==="
rg '\\\\\\|' en/docs/develop/integration-artifacts/supporting/types.md

Repository: wso2/docs-integrator

Length of output: 13225

🏁 Script executed:

# Check file size to understand its scope
wc -l en/docs/develop/integration-artifacts/supporting/types.md

Repository: wso2/docs-integrator

Length of output: 126

Use HTML entity &#124; instead of backslash-escaped pipe in inline code.

In the "Edit a field" table, the return type example uses string\|error. When backslash-escaped pipes appear inside inline code blocks within Markdown tables, they may render as visible backslashes depending on the Markdown processor. Use the HTML entity &#124; instead, which consistently renders as | without backslashes.

Proposed change 
-| **Field Type** | The return type (for example, `string\|error`). |
+| **Field Type** | The return type (for example, `string&#124;error`). |
🤖 Prompt for AI Agents 
Verify each finding against the current code and only fix it if needed.

In `@en/docs/develop/integration-artifacts/supporting/types.md` around lines 223 -
227, Replace the backslash-escaped pipe inside the inline code example for the
"Field Type" cell: locate the table row containing "**Field Type**" and the
example `string\|error` and change the inline code to use the HTML entity for
pipe (e.g., `string&#124;error`) so the pipe displays correctly without a
visible backslash.

Expand **Advanced Configurations** to set:

| Option | Description |
|---|---|
| **Field Configuration** | Free-form JSON configuration such as field-level cache settings. |
| **Request Context** | Inject a context value used to pass meta-information among GraphQL resolvers. |
| **Field Metadata** | Inject the field metadata used to access information about the field in a GraphQL document. |

#### Service Class Designer

Click **Implement** to open the **Service Class Designer**, where you add class state and method implementations.

![Service Class Designer showing Class Variables and Methods sections](/img/develop/integration-artifacts/supporting/types/service-class-designer.png)

**Class Variables** — click **+ Variable** to open the **Add Variable** panel:

| Control | Description |
|---|---|
| **Variable Name** | The variable identifier. |
| **Variable Type** | The variable type. |
| **Default Value** | The initial value assigned at construction. |

**Methods** — click **+ Method** to open the **Add Method** panel. Choose the method kind from the dropdown — **resource**, **remote**, or **init** — then fill in:

| Control | Description |
|---|---|
| **Function Name** | The method name. Not shown for `init`. |
| **Description** | Documentation for the method. |
| **Parameters** | Use **+ Add Parameter** to add inputs (name, type, optional default value). |
| **Return Type** | The method return type. Not shown for `init`. |

Use the pencil and trash icons next to each existing method to edit or remove it.

</TabItem>
<TabItem value="code" label="Ballerina Code">

```ballerina
type PaymentMethod CreditCard|BankTransfer|DigitalWallet;
# Represents a pet shelter exposed through GraphQL.
public service class Shelter {
private final string name;
private final string location;
private int capacity;

function init(string name, string location, int capacity) {
self.name = name;
self.location = location;
self.capacity = capacity;
}

# Returns the shelter name.
resource function get name() returns string|error {
return self.name;
}

resource function get location() returns string {
return self.location;
}

resource function get capacity() returns int {
return self.capacity;
}

remote function updateCapacity(int newCapacity) returns int {
self.capacity = newCapacity;
return self.capacity;
}
}
```

</TabItem>
</Tabs>

### Union

A union allows a value to be one of several member types.

<Tabs>
<TabItem value="ui" label="Visual Designer" default>

Select **Union** from the **Kind** dropdown, then add each member type using **+**. Members can be built-in types or other named types.

**Advanced Options**:

| Option | Description |
|---|---|
| **Is Readonly Type** | Wrap the union as `readonly & T` so values are immutable. |
| **Accessible by Other Integrations** | Add the `public` qualifier so the type can be imported from other packages. |

</TabItem>
<TabItem value="code" label="Ballerina Code">

```ballerina
public type PaymentMethod CreditCard|BankTransfer|DigitalWallet;

type CreditCard record {|
string cardNumber;
Expand All @@ -175,43 +340,57 @@ type DigitalWallet record {|
</TabItem>
</Tabs>

### Tables
### Array

An array defines an ordered list of values of a single member type.

<Tabs>
<TabItem value="ui" label="Visual Designer" default>

Select **Table** from the **Kind** dropdown to define an in-memory keyed collection. Specify the row type and the key field.
Select **Array** from the **Kind** dropdown.

| Control | Description |
|---|---|
| **Type of the Array** | The member type (required). |
| **Size of the Array** | A fixed length. Leave empty for an unbounded array. |

**Advanced Options**:

| Option | Description |
|---|---|
| **Is Readonly Type** | Wrap the array as `readonly & T[]` so it cannot be mutated. |
| **Accessible by Other Integrations** | Add the `public` qualifier so the type can be imported from other packages. |

</TabItem>
<TabItem value="code" label="Ballerina Code">

```ballerina
type ProductTable table<Product> key(id);

type Product record {|
readonly string id;
string name;
decimal price;
int stock;
|};

// Usage
ProductTable products = table [
{id: "P001", name: "Widget", price: 9.99, stock: 100},
{id: "P002", name: "Gadget", price: 24.99, stock: 50}
];
// Unbounded array
public type LineItems string[];

Product? widget = products["P001"];
// Fixed-length array
type Coordinates float[3];
```

</TabItem>
</Tabs>

## Map types

The visual designer does not expose **Map** as a Kind. To model dynamic key/value data, define a record instead:

- For a known set of keys, use a closed record (`record {| ... |}`).
- For arbitrary string keys with a uniform value type, use an open record with **Allow Additional Fields** enabled.

If you are editing source directly, the equivalent Ballerina form is `map<T>` — for example, `map<string>` for a string-valued map. Types declared this way appear as opaque references in the type diagram.

## Best practices

| Practice | Description |
|---|---|
| **Closed records** | Use `record {\| ... \|}` to restrict fields to only those defined |
| **Dedicated files** | Keep type definitions in separate `types.bal` files |
| **Descriptive names** | Name types after their domain concept (for example, `OrderRequest`, not `Data`) |
| **Reuse across artifacts** | Define types once and import them in services, event handlers, and functions |
| **Closed records** | Leave **Allow Additional Fields** unchecked unless you actually need extra keys. Closed records catch typos at compile time. |
| **Dedicated files** | Keep type definitions in separate `types.bal` files and import them where needed. |
| **Descriptive names** | Name types after their domain concept (for example, `OrderRequest`, not `Data`). |
| **Reuse across artifacts** | Define types once and reference them from services, event handlers, and functions. |
| **Prefer Readonly over reassignment** | Mark fields or whole types **Readonly** for immutable data, instead of relying on convention. |
| **Use records instead of maps in the designer** | The designer cannot edit `map<T>` types. Model dynamic data as records (open records when keys are unknown). |
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