---
title: How to Add a Custom Property to an Entity with API
slug: /developers/how-to-add-custom-property-to-an-entity
---

# How to Add a Custom Property to an Entity with API

This tutorial will create a custom property for a `table` entity.

A custom property can store a value for each entity, such as a table's size for each `table` entity. 

### Step 1: Get the table entity type.

All OpenMetadata APIs are secured so make sure to add the proper headers. API requests can be sent with your [JWT token](https://docs.open-metadata.org/latest/sdk#bot-token)

```commandline
curl -X GET http://localhost:8585/api/v1/metadata/types/name/table
```

After the API call, you will get a response like this.

```json
{
  "id": "7f0b032f-cdc8-4573-abb0-22165dcd8e07",
  "name": "table",
  ...
}
```

Take note of the `id` that corresponds to `"name": "table"` from the above response... `7f0b032f-cdc8-4573-abb0-22165dcd8e07`.

### Step 2: Get the field types with `category=field`

> OpenMetadata's UI supports three field types:
>
> - String
> - Markdown
> - Integer

```commandline
 curl -X GET http://localhost:8585/api/v1/metadata/types?category=field&limit=20
```

This API call will return available field types, grab the id of the `"name": "string"` field type. i.e `7531f881-c37c-4e39-9154-4bdf0802e05e`

### Step 3: Make a call to create the custom property for the table entity 

Create a payload using the field type id from the previous step and send a PUT request to the table id from the first request to create the custom property for tables.

```commandline
curl -X PUT http://localhost:8585/api/v1/metadata/types/7f0b032f-cdc8-4573-abb0-22165dcd8e07 \     #table id from step 1
-H "Content-Type: application/json" \
-d '{
  "description": "Property for tracking the tableSize.",
  "name": "tableSize",
  "propertyType": {
    "id": "7531f881-c37c-4e39-9154-4bdf0802e05e",                                                  #string field type id from step 2
    "type": "type"
  }
}'
```

### Step 4: Get the custom properties for the table entity

Verify the previous step with the following request. Look in `"customProperties"` for our new property.

```commandline
curl -X GET http://localhost:8585/api/v1/metadata/types/name/table?fields=customProperties
```

**Response**

```json
{
  "id": "7f0b032f-cdc8-4573-abb0-22165dcd8e07",
  "name": "table",
  "customProperties": [
    {
      "name": "tableSize",
      "description": "Property for tracking the tableSize.",
      "propertyType": {
        "id": "7531f881-c37c-4e39-9154-4bdf0802e05e",
        "type": "type",
        "name": "string",
        "fullyQualifiedName": "string",
        "description": "\"A String type.\"",
        "displayName": "string",
        "href": "http://localhost:8585/api/v1/metadata/types/7531f881-c37c-4e39-9154-4bdf0802e05e"
      }
    }
  ]
}
```

So for all table entities, we have a `tableSize` custom property available now, let’s add the value for it for the `raw_product_catalog` table.

### Step 5: Add/Edit the value of the custom property for the entity.

All the custom properties value for the entity will be stored in the `extension` attribute.

Let’s assume you have `raw_product_catalog` table, find it's id with the API call below.

```commandline
curl -X GET http://localhost:8585/api/v1/tables?limit=1000
```

If the table's id was `208598fc-bd5f-458c-bf98-59224e1620c7` and we are adding a value to the custom property for the first time, our PATCH API request will be like this.

```commandline
curl -X PATCH http://localhost:8585/api/v1/tables/208598fc-bd5f-458c-bf98-59224e1620c7 \
--header 'Content-Type: application/json-patch+json' \
--data '[
  {
    "op": "add",
    "path": "/extension",
    "value": {
      "tableSize": "50GB"
    }
  }
]'
```

When Changing the value of the custom property the request should be like this,

```commandline
curl -X PATCH http://localhost:8585/api/v1/tables/208598fc-bd5f-458c-bf98-59224e1620c7 \
--header 'Content-Type: application/json-patch+json' \
--data '[
  {
    "op": "replace",
    "path": "/extension/tableSize",
    "value": "60GB"
  }
]'
```

When finished your new custom property should be present and updated for the `raw_product_catalog` table

{% image src="/images/v1.8/developers/custom-properties.png" alt="Custom property added to table" caption=" " /%}

### Step 5: Delete custom property.

To finish this tutorial, delete the newly created custom property, `tableSize` by going to [**Settings >> Custom Properties >> Tables**](http://localhost:8585/settings/customProperties/tables). 

Click **Delete Property**, then **Confirm**.

{% image src="/images/v1.8/developers/delete-custom-properties.png" alt="Delete custom property added to table" caption=" " /%}