Bind in nested component

[stalkerg]

Example: https://svelte.technology/repl?version=1.25.0&gist=ef7e0e85bebbe18bcfb53ffd7e9ebc44
My explanation:
during creating component we have the code:

if (options.target) {
  this._fragment.create();
  this._fragment.mount(options.target, null);
}

if we work with nested component target is undefined and DOM will not create on this stage.
Several lines below we call bindings

callAll(this._bindings); 

but without DOM and will get the error.

[stalkerg]

Problem worse because exists without yield too:
https://svelte.technology/repl?version=1.25.0&gist=660895060e64a52f62409adb0254fb21

[stalkerg]

This patch fix my problem but break runtime/bindings-before-oncreate test (and behaviour)

diff --git a/src/generators/dom/Block.ts b/src/generators/dom/Block.ts
index ff58a4e..e7e7940 100644
--- a/src/generators/dom/Block.ts
+++ b/src/generators/dom/Block.ts
@@ -46,6 +46,7 @@ export default class Block {
 		claim: CodeBuilder;
 		hydrate: CodeBuilder;
 		mount: CodeBuilder;
+		bindings: CodeBuilder;
 		intro: CodeBuilder;
 		update: CodeBuilder;
 		outro: CodeBuilder;
@@ -92,6 +93,7 @@ export default class Block {
 			claim: new CodeBuilder(),
 			hydrate: new CodeBuilder(),
 			mount: new CodeBuilder(),
+			bindings: new CodeBuilder(),
 			intro: new CodeBuilder(),
 			update: new CodeBuilder(),
 			outro: new CodeBuilder(),
@@ -257,6 +259,7 @@ export default class Block {
 			properties.addBlock(deindent`
 				mount: function ( #target, anchor ) {
 					${this.builders.mount}
+					${this.builders.bindings}
 				},
 			`);
 		}
diff --git a/src/generators/dom/index.ts b/src/generators/dom/index.ts
index 55c6599..5efb963 100644
--- a/src/generators/dom/index.ts
+++ b/src/generators/dom/index.ts
@@ -228,7 +228,7 @@ export default function dom(
 			}
 			
 			${generator.hasComponents && `@callAll(this._oncreate);`}
-			${generator.hasComplexBindings && `@callAll(this._bindings);`}
+			${generator.hasComplexBindings && `options.target && @callAll(this._bindings);`}
 
 			${templateProperties.oncreate && deindent`
 				if ( options._root ) {
diff --git a/src/generators/dom/visitors/Component/Component.ts b/src/generators/dom/visitors/Component/Component.ts
index 7145f5d..a5bffec 100644
--- a/src/generators/dom/visitors/Component/Component.ts
+++ b/src/generators/dom/visitors/Component/Component.ts
@@ -232,6 +232,9 @@ export default function visitComponent(
 	block.builders.mount.addLine(
 		`${name}._fragment.mount( ${targetNode}, ${anchorNode} );`
 	);
+	block.builders.bindings.addLine(
+		`@callAll( ${name}._fragment._bindings );`
+	);
 
 	if (!local.update.isEmpty()) block.builders.update.addBlock(local.update);
 }

[stalkerg]

Maybe it is a bad idea to try to get states from nested components in oncreate function. Anyway, you can ask component directly.
UPDATE
I think much better will be if we just stop update DOM (component.update) in this situation because in any case after we create DOM from actual data. But I can't implement that without sending extra var for many functions...

[stalkerg]

Second solution, maybe much better without new broken test:

diff --git a/src/generators/dom/index.ts b/src/generators/dom/index.ts
index 55c6599..09b54e8 100644
--- a/src/generators/dom/index.ts
+++ b/src/generators/dom/index.ts
@@ -123,7 +123,8 @@ export default function dom(
 		${computations.length &&
 			`@recompute( this._state, newState, oldState, false )`}
 		@dispatchObservers( this, this._observers.pre, newState, oldState );
-		${block.hasUpdateMethod && `this._fragment.update( newState, this._state );`}
+
+		${block.hasUpdateMethod && `withoutDomUpdate || this._fragment.update( newState, this._state );`}
 		@dispatchObservers( this, this._observers.post, newState, oldState );
 		${generator.hasComponents && `@callAll(this._oncreate);`}
 		${generator.hasComplexBindings && `@callAll(this._bindings);`}
@@ -213,6 +214,7 @@ export default function dom(
 
 			this._fragment = @create_main_fragment( this._state, this );
 
+			this._protectDomUpdate = false;
 			if ( options.target ) {
 				${generator.hydratable
 					? deindent`
@@ -225,10 +227,13 @@ export default function dom(
 						this._fragment.create();
 					`}
 				this._fragment.${block.hasIntroMethod ? 'intro' : 'mount'}( options.target, null );
+			} else {
+				this._protectDomUpdate = true;
 			}
 			
 			${generator.hasComponents && `@callAll(this._oncreate);`}
 			${generator.hasComplexBindings && `@callAll(this._bindings);`}
+			this._protectDomUpdate = false;
 
 			${templateProperties.oncreate && deindent`
 				if ( options._root ) {
@@ -242,7 +247,7 @@ export default function dom(
 
 		@assign( ${prototypeBase}, ${proto});
 
-		${name}.prototype._set = function _set ( newState ) {
+		${name}.prototype._set = function _set ( newState, withoutDomUpdate ) {
 			${_set}
 		};
 
diff --git a/src/generators/dom/visitors/shared/binding/getSetter.ts b/src/generators/dom/visitors/shared/binding/getSetter.ts
index 784e1d7..cfbe591 100644
--- a/src/generators/dom/visitors/shared/binding/getSetter.ts
+++ b/src/generators/dom/visitors/shared/binding/getSetter.ts
@@ -29,10 +29,10 @@ export default function getSetter({
 			${computed
 				? `#component._set({ ${dependencies
 						.map((prop: string) => `${prop}: state.${prop}`)
-						.join(', ')} });`
+						.join(', ')} }, #component._protectDomUpdate);`
 				: `#component._set({ ${dependencies
 						.map((prop: string) => `${prop}: #component.get( '${prop}' )`)
-						.join(', ')} });`}
+						.join(', ')} }, #component._protectDomUpdate);`}
 		`;
 	}
 
@@ -42,11 +42,11 @@ export default function getSetter({
 			${snippet} = ${value};
 			#component._set({ ${dependencies
 				.map((prop: string) => `${prop}: state.${prop}`)
-				.join(', ')} });
+				.join(', ')} }, #component._protectDomUpdate);
 		`;
 	}
 
-	return `#component._set({ ${name}: ${value} });`;
+	return `#component._set({ ${name}: ${value} }, #component._protectDomUpdate);`;
 }
 
 function isComputed(node: Node) {

I can make tests and PR if my approach will be accepted.

[Rich-Harris]

It looks like this is fixed by #709 (i.e. it's the same basic issue as #708), so I'm going to focus on finishing that PR

[stalkerg]

Yep, this issue fixed.