Copy docs/snippets/ to assets/svelte/mdx

Author: RTLS

Dockerfile

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 COPY assets assets
 
-# Copy shared MDX files to both svelte and snippets directories
-COPY shared_mdx/*.mdx assets/svelte/mdx/
-COPY shared_mdx/*.mdx docs/snippets/
+# Copy MDX snippets from docs to assets for CopyForChatGPT button
+COPY docs/snippets/function-transform-snippet.mdx assets/svelte/mdx/function-transform-snippet.mdx
 
 # install all npm packages in assets directory
 WORKDIR /app/assets

assets/svelte/mdx/function-transform-snippet.mdx

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-../../../shared_mdx/function-transform-snippet.mdx
+../../../docs/snippets/function-transform-snippet.mdx

docs/snippets/function-transform-snippet.mdx

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+## Function transform
+
+Function transforms allow you to write custom [Elixir](https://elixir-lang.org/) code to transform your messages. This is useful for more complex transformations that are not possible with the path transform, such as:
+
+- Specifying a format that is necessary for your sink destination
+- Sanitizing sensitive data, such as PII or payment card data
+- Converting timestamp formats
+- Adding computed fields
+- And much more!
+
+### Function syntax
+
+Every function transform is implemented as an Elixir `transform/4` function:
+
+```Elixir
+def transform(action, record, changes, metadata) do
+  # Your transform here
+end
+```
+
+The `transform/4` function receives each key from the [message object](/reference/messages) as an argument:
+
+- `record`: The full record object
+- `changes`: The changes object
+- `action`: The action type (insert, update, delete)
+- `metadata`: The metadata object
+
+<Info>
+  Your transform must define the `transform/4` function and may not define any other functions.
+</Info>
+
+### Elixir standard library
+
+The function transform allows you to use a subset of the Elixir standard library, including:
+
+- [String](https://hexdocs.pm/elixir/String.html)
+- [Map](https://hexdocs.pm/elixir/Map.html)
+- [Enum](https://hexdocs.pm/elixir/Enum.html)
+- [Date](https://hexdocs.pm/elixir/Date.html), [DateTime](https://hexdocs.pm/elixir/DateTime.html), and [NaiveDateTime](https://hexdocs.pm/elixir/NaiveDateTime.html)
+- [Kernel](https://hexdocs.pm/elixir/Kernel.html)
+- [Decimal](https://hexdocs.pm/decimal/readme.html)
+- [URI](https://hexdocs.pm/elixir/URI.html)
+
+Other parts of the Elixir standard library are not yet supported.  If you need something specific, please [let us know](https://github.com/sequinstream/sequin/issues/new/choose)
+and we will be happy to help.
+
+### Examples
+
+Here are some examples of how to use the function transform:
+
+#### Extract the record ID
+
+```Elixir
+def transform(action, record, changes, metadata) do
+  record["id"]
+end
+```
+
+#### Format for webhook
+
+```Elixir
+# Format the record for ElastiCache with a specific key structure
+def transform(action, record, changes, metadata) do
+  record_id = record["id"]
+
+  %{
+    key: "#{metadata.table_schema}.#{metadata.table_name}.#{record_id}",
+    value: record,
+    ttl: 3600 # 1 hour TTL
+  }
+end
+```
+
+<Note>
+  Both `record` and `changes` use string keys for access (ie. `record["id"]`).
+
+  In contrast, the `metadata` object uses atom keys (ie. `metadata.table_schema`).
+
+  This is because the `record` and `changes` objects are dynamically typed- they depend on the schema of the connected Postgres table. Metadata, on the other hand, is statically typed and will always have the same keys.
+
+  See the [Elixir Map docs](https://hexdocs.pm/elixir/1.12/Map.html) for more information on the difference between string and atom keys.
+</Note>
+
+#### Sanitize sensitive data
+
+```Elixir
+# Remove or mask sensitive fields
+def transform(action, record, changes, metadata) do
+  record
+  |> Map.drop(["password", "credit_card", "ssn"])
+  |> Map.update!("email", fn email ->
+    [name, domain] = String.split(email, "@")
+    masked_name = String.slice(name, 0, 2) <> String.duplicate("*", String.length(name) - 2)
+    masked_name <> "@" <> domain
+  end)
+end
+```
+
+#### Add computed property
+
+```Elixir
+# Add a computed full name field
+def transform(action, record, changes, metadata) do
+  first_name = record["first_name"]
+  last_name = record["last_name"]
+  full_name = first_name <> " " <> last_name
+  name_length = String.length(full_name)
+ 
+  %{
+    full_name: full_name,
+    name_length: name_length
+  }
+end
+```
+
+#### Convert timestamp formats
+
+```Elixir
+# Convert timestamp formats
+def transform(action, record, changes, metadata) do
+  timestamp = record["timestamp"]
+
+  %{
+    unix_timestamp: DateTime.to_unix(timestamp),
+    truncated_timestamp: DateTime.truncate(timestamp, :second),
+    iso8601_timestamp: DateTime.to_iso8601(timestamp)
+  }
+end
+```