Example of updating a deeply nested document with @sanity/client ?

Great question! Here are some practical examples for patching deeply nested documents with @sanity/client:

Basic Nested Object Update

For objects nested 2-3 levels deep, you can use dot notation in your path:

client
  .patch('document-id')
  .set({
    'level1.level2.level3.fieldName': 'new value'
  })
  .commit()

Updating Objects in Arrays

When you need to update a specific object within an array, use the JSONMatch path syntax with _key filtering:

client
  .patch('document-id')
  .set({
    'items[_key=="abc123"].title': 'Updated Title',
    'items[_key=="abc123"].nested.deepField': 'Deep value'
  })
  .commit()

Deeply Nested Array Updates

For arrays nested within arrays, you can chain conditions:

client
  .patch('document-id')
  .set({
    'sections[_key=="section1"].blocks[_key=="block2"].content': 'New content',
    'sections[_key=="section1"].blocks[_key=="block2"].metadata.author': 'John'
  })
  .commit()

Inserting into Nested Arrays

To insert items into a nested array, use the insert() method:

client
  .patch('document-id')
  .insert('after', 'sections[_key=="section1"].items[-1]', [
    {
      _key: 'newItem123',
      _type: 'item',
      title: 'New nested item'
    }
  ])
  .commit()

Multiple Operations in One Patch

You can chain multiple operations for complex updates:

client
  .patch('document-id')
  .set({
    'level1.level2.field1': 'value1'
  })
  .setIfMissing({
    'level1.level2.field2': 'default value'
  })
  .unset(['level1.level2.oldField'])
  .commit()

Important Tips

• Always use _key when targeting specific array items - this is more reliable than using array indices
• Path syntax supports conditions like [_key=="value"] or even [_type=="cta"] to filter array elements
• Array positions: Use [-1] for the last element, [0] for first
• The patches documentation has more details on all available operations

The key to deeply nested updates is understanding that you can combine dot notation for objects with bracket notation and conditions for arrays, creating paths like parent.children[_key=="child1"].grandchildren[_key=="gc1"].field.