Add migrate example

docs-test-gen/Cargo.toml

@@ -8,7 +8,7 @@ edition = "2021"
 anyhow = "1.0.82"
 glob = "0.3.1"
 phf = { version = "0.11.2", features = ["macros"] }
-pulldown-cmark = { version = "0.10.3", default-features = false }
+pulldown-cmark = { version = "0.11.0", default-features = false }
 strum = { version = "0.26.2", features = ["derive"] }
 
 [dev-dependencies]

docs-test-gen/src/main.rs

@@ -7,6 +7,7 @@ use strum::{AsRefStr, EnumIter, IntoEnumIterator};
 
 static TEMPLATES: phf::Map<&'static str, &'static str> = phf_map! {
     "core" => include_str!("../templates/core.tpl"),
+    "core-migrate" => include_str!("../templates/core-migrate.tpl"),
     "execute" => include_str!("../templates/execute.tpl"),
 };
 

docs-test-gen/templates/core-migrate.tpl

@@ -0,0 +1,25 @@
+use cosmwasm_std::*;
+use cosmwasm_schema::cw_serde;
+
+#[derive(Default)]
+struct OldData {}
+
+#[cw_serde]
+struct MigrateMsg {}
+
+fn from_slice<T: Default>(_data: &[u8]) -> StdResult<T> {
+    Ok(T::default())
+}
+
+fn to_vec<T>(_data: &T) -> StdResult<Vec<u8>> {
+    Ok(Vec::new())
+}
+
+fn transform(_old_data: OldData) -> () {
+    ()
+}
+
+#[test]
+fn doctest() {
+  {{code}}
+}

src/pages/core/entrypoints/migrate.mdx

@@ -9,8 +9,8 @@ import { Callout } from "nextra/components";
 This is another special endpoint. It is, just like `instantiate`, not called
 frequently.
 
-`migrate` is only called once you upload a new version to the chain
-and lets you run all the required changes to the storage.
+`migrate` is only called once you upload a new version to the chain and lets you
+run all the required changes to the storage.
 
 Let's say your storage has the following layout, expressed as JSON for
 simplicity's sake:
@@ -45,6 +45,42 @@ transform it.
 That's what you do in the `migrate` entrypoint. You transform the structure of
 the storage in there.
 
+## Example
+
+```rust filename="contract.rs" template="core-migrate"
+const STATE_VERSION: u64 = 1;
+
+#[entry_point]
+pub fn migrate(deps: DepsMut, _env: Env, _msg: MigrateMsg) -> StdResult<Response> {
+    // Check if the state version is olden than the current one
+    let Some(current_state_version) = deps.storage.get(b"state") else {
+        return Err(StdError::generic_err("State not found"));
+    };
+    let current_state_version: u64 = from_slice(&current_state_version)?;
+
+    if current_state_version < STATE_VERSION {
+        return Ok(Response::default());
+    }
+
+    // Load the old data
+    let Some(old_data) = deps.storage.get(b"persisted_data") else {
+      return Err(StdError::generic_err("Data not found"));
+    };
+    // Deserialize it from the old format
+    let old_data: OldData = from_slice(&old_data)?;
+
+    // Transform it
+    let new_data = transform(old_data);
+
+    // Serialize the new data
+    let new_data = to_vec(&new_data)?;
+    // Store the new data
+    deps.storage.set(b"persisted_data", &new_data);
+
+    Ok(Response::default())
+}
+```
+
 ## Definition
 
 ```rust filename="contract.rs" template="core"