Add else to retrieve and var.

If the named variable isn't set, then (and only then) an else clause is executed to return a value.

This is useful for defaults, but also for sub-expressions where it only does things like prompting the user if the value isn't set.

Part of #36.

README.md

@@ -554,6 +554,7 @@ Returns a variable from environment. See also `let`.
 
 Required parameters:
 - `name` - A named variable in environment to get.
+- `else` - If the key does not exist, execute this sub-expression and return its value instead.
 
 #### let
 
@@ -605,6 +606,7 @@ Unlike `let`, this affects multiple runs. See also `store` and `delete`.
 Required parameters:
 - `store` - (optional) The ID of the store to store in. If omitted, will use environment.store. By convention you should name a store like `komoroske.com:name`, to avoid collisions.
 - `key` - The key to retrieve.
+- `else` - If the key does not exist, execute this sub-expression and return its value instead.
 
 Environment:
 - `store` - The default store ID to use if one is not provided.

seed-schema.json

@@ -2057,6 +2057,27 @@
 									"description": "The name of the variable in environment to fetch"
 								}
 							]
+						},
+						"else": {
+							"anyOf": [
+								{
+									"$ref": "#/definitions/seedData"
+								},
+								{
+									"$ref": "#/definitions/seedData/anyOf/0/properties/prompt/anyOf/1"
+								},
+								{
+									"anyOf": [
+										{
+											"not": {}
+										},
+										{
+											"$ref": "#/definitions/seedData/anyOf/5/properties/value/anyOf/2/anyOf/1/additionalProperties/anyOf/2"
+										}
+									],
+									"description": "The sub-expression to execute to get a value if value is undefined"
+								}
+							]
 						}
 					},
 					"required": [
@@ -2350,6 +2371,27 @@
 									"description": "The name of the variable in environment to retrieve"
 								}
 							]
+						},
+						"else": {
+							"anyOf": [
+								{
+									"$ref": "#/definitions/seedData"
+								},
+								{
+									"$ref": "#/definitions/seedData/anyOf/0/properties/prompt/anyOf/1"
+								},
+								{
+									"anyOf": [
+										{
+											"not": {}
+										},
+										{
+											"$ref": "#/definitions/seedData/anyOf/5/properties/value/anyOf/2/anyOf/1/additionalProperties/anyOf/2"
+										}
+									],
+									"description": "The sub-expression to execute to get a value if value is undefined"
+								}
+							]
 						}
 					},
 					"required": [

src/grow.ts

@@ -586,7 +586,11 @@ const growVar = async (seed : Seed<SeedDataVar>, env : Environment) : Promise<Va
 	const nameInput = extractString(await getProperty(seed, env, data.name));
 	const name = env.getVarName(nameInput);
 	//environment.get will properly refuse to get secretValues.
-	return env.get(name);
+	const result = env.get(name);
+	if (result === null) {
+		return await getProperty(seed, env, data.else, null);
+	}
+	return result;
 };
 
 const growLet = async (seed : Seed<SeedDataLet>, env : Environment) : Promise<Value> => {
@@ -632,7 +636,9 @@ const growRetrieve = async (seed : Seed<SeedDataRetrieve>, env : Environment) :
 	const storeID = env.getStoreID(rawStoreID);
 	const key = extractString(await getProperty(seed, env, data.name));
 	const result = seed.garden.profile.retrieve(storeID, key);
-	if (result === undefined) return null;
+	if (result === undefined) {
+		return await getProperty(seed, env, data.else, null);
+	}
 	return result;
 };
 

src/types.ts

@@ -768,7 +768,8 @@ export type SeedDataThrow = z.infer<typeof seedDataThrow>;
 const seedDataConfigVar = {
 	type: z.literal('var'),
 	properties: {
-		name: varName.describe('The name of the variable in environment to fetch')
+		name: varName.describe('The name of the variable in environment to fetch'),
+		else: inputValue.optional().describe('The sub-expression to execute to get a value if value is undefined'),
 	}
 };
 
@@ -823,6 +824,7 @@ const seedDataConfigRetrieve = {
 	properties: {
 		store: storeID.optional().describe('The store ID to use'),
 		name: storeKey.describe('The name of the variable in environment to retrieve'),
+		else: inputValue.optional().describe('The sub-expression to execute to get a value if value is undefined'),
 	}
 };
 

test/base/a_test.json

@@ -279,6 +279,48 @@
         "throw-test": {
             "type": "throw",
             "error": "This is an error"
+        },
+        "var-with-value-set": {
+            "type": "let",
+            "name": "val",
+            "value": 3,
+            "block": {
+                "type": "var",
+                "name": "val",
+                "else": {
+                    "type": "throw",
+                    "error": "This shouldn't happen since val is set"
+                }
+            }
+        },
+        "var-without-value-set": {
+            "type": "var",
+            "name": "val",
+            "else": 5
+        },
+        "retrieve-with-value-set": {
+            "type": "array",
+            "return": "last",
+            "items": [
+                {
+                    "type": "store",
+                    "name": "val",
+                    "value": 3
+                },
+                {
+                    "type": "retrieve",
+                    "name": "val",
+                    "else": {
+                        "type": "throw",
+                        "error": "This shouldn't happen since val is set"
+                    }
+                }
+            ]
+        },
+        "retrieve-without-value-set": {
+            "type": "retrieve",
+            "name": "val",
+            "else": 5
         }
     }
 }

test/base/test.ts

@@ -845,6 +845,38 @@ Suffix`;
 		});
 	});
 
+	it('var set else test', async () => {
+		const garden = loadTestGarden();
+		const seed = await garden.seed('var-with-value-set');
+		const actual = await seed.grow();
+		const golden = 3;
+		assert.deepStrictEqual(actual, golden);
+	});
+
+	it('var unset else test', async () => {
+		const garden = loadTestGarden();
+		const seed = await garden.seed('var-without-value-set');
+		const actual = await seed.grow();
+		const golden = 5;
+		assert.deepStrictEqual(actual, golden);
+	});
+
+	it('retrieve set else test', async () => {
+		const garden = loadTestGarden();
+		const seed = await garden.seed('retrieve-with-value-set');
+		const actual = await seed.grow();
+		const golden = 3;
+		assert.deepStrictEqual(actual, golden);
+	});
+
+	it('retrieve unset else test', async () => {
+		const garden = loadTestGarden();
+		const seed = await garden.seed('retrieve-without-value-set');
+		const actual = await seed.grow();
+		const golden = 5;
+		assert.deepStrictEqual(actual, golden);
+	});
+
 });
 
 describe('expandSeedPacket tests', () => {