From 21020740248bb7f4b27de22feb8137cc36eb799b Mon Sep 17 00:00:00 2001
From: Julien Robert <julien@rbrt.fr>
Date: Mon, 24 Jul 2023 17:46:54 +0200
Subject: [PATCH] feat(collections): implement `appmodule.HasGenesis` interface
 (#17021)

---
 collections/CHANGELOG.md | 8 ++++++--
 collections/genesis.go   | 8 ++++++++
 collections/schema.go    | 6 ++++++
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/collections/CHANGELOG.md b/collections/CHANGELOG.md
index 9b04bc86e9cd..291ec0b9a478 100644
--- a/collections/CHANGELOG.md
+++ b/collections/CHANGELOG.md
@@ -35,14 +35,18 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 * [#17024](https://github.com/cosmos/cosmos-sdk/pull/17024) - Introduces `Triple`, a composite key with three keys.
 
+### Improvements
+
+* [#17021](https://github.com/cosmos/cosmos-sdk/pull/17021) Make collections implement the `appmodule.HasGenesis` interface.
+
 ## [v0.3.0](https://github.com/cosmos/cosmos-sdk/releases/tag/collections%2Fv0.3.0)
 
 ### Features
 
 * [#16074](https://github.com/cosmos/cosmos-sdk/pull/16607) - Introduces `Clear` method for `Map` and `KeySet`
 * [#16773](https://github.com/cosmos/cosmos-sdk/pull/16773)
-  * Adds `AltValueCodec` which provides a way to decode a value in two ways.
-  * Adds the possibility to specify an alternative way to decode the values of `KeySet`, `indexes.Multi`, `indexes.ReversePair`. 
+    * Adds `AltValueCodec` which provides a way to decode a value in two ways.
+    * Adds the possibility to specify an alternative way to decode the values of `KeySet`, `indexes.Multi`, `indexes.ReversePair`. 
 
 ## [v0.2.0](https://github.com/cosmos/cosmos-sdk/releases/tag/collections%2Fv0.2.0)
 
diff --git a/collections/genesis.go b/collections/genesis.go
index 0c593e4adfd8..c2db579b1126 100644
--- a/collections/genesis.go
+++ b/collections/genesis.go
@@ -3,6 +3,7 @@ package collections
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 )
@@ -39,6 +40,13 @@ func (m Map[K, V]) exportGenesis(ctx context.Context, writer io.Writer) error {
 
 	it, err := m.Iterate(ctx, nil)
 	if err != nil {
+		// if the iterator is invalid, the state can be empty
+		// and we can just return an empty array.
+		if errors.Is(err, ErrInvalidIterator) {
+			_, err = io.WriteString(writer, "]")
+			return err
+		}
+
 		return err
 	}
 	defer it.Close()
diff --git a/collections/schema.go b/collections/schema.go
index e05058f144c1..8cc851166f61 100644
--- a/collections/schema.go
+++ b/collections/schema.go
@@ -161,6 +161,12 @@ func NewSchemaFromAccessor(accessor func(context.Context) store.KVStore) Schema
 	}
 }
 
+// IsOnePerModuleType implements the depinject.OnePerModuleType interface.
+func (s Schema) IsOnePerModuleType() {}
+
+// IsAppModule implements the appmodule.AppModule interface.
+func (s Schema) IsAppModule() {}
+
 // DefaultGenesis implements the appmodule.HasGenesis.DefaultGenesis method.
 func (s Schema) DefaultGenesis(target appmodule.GenesisTarget) error {
 	for _, name := range s.collectionsOrdered {