[wip] support for previous state

src/actions/index.js

@@ -158,7 +158,8 @@ export function notifyObservers(payload) {
         const {
             id,
             event,
-            props
+            props,
+            prevProps
         } = payload
 
         const {
@@ -359,6 +360,25 @@ export function notifyObservers(payload) {
                         value: view(propLens, layout)
                     };
                 });
+                payload.prevInputs = inputs.map(inputObject => {
+                    if (id === inputObject.id && prevProps) {
+                        return {
+                            id: id,
+                            property: inputObject.property,
+                            value: prevProps[inputObject.property]
+                        };
+                    } else {
+                        const propLens = lensPath(
+                            concat(paths[inputObject.id],
+                            ['props', inputObject.property]
+                        ));
+                        return {
+                            id: inputObject.id,
+                            property: inputObject.property,
+                            value: view(propLens, layout)
+                        };
+                    }
+                });
             }
             if (state.length > 0) {
                 payload.state = state.map(stateObject => {
@@ -372,8 +392,28 @@ export function notifyObservers(payload) {
                         value: view(propLens, layout)
                     };
                 });
+                payload.prevState = state.map(stateObject => {
+                    if (id === stateObject.id && prevProps) {
+                        return {
+                            id: id,
+                            property: stateObject.property,
+                            value: prevProps[stateObject.property]
+                        };
+                    } else {
+                        const propLens = lensPath(
+                            concat(paths[stateObject.id],
+                            ['props', stateObject.property]
+                        ));
+                        return {
+                            id: stateObject.id,
+                            property: stateObject.property,
+                            value: view(propLens, layout)
+                        };
+                    }
+                });
             }
 
+
             promises.push(fetch(`${urlBase(config)}_dash-update-component`, {
                 method: 'POST',
                 headers: {

src/components/core/NotifyObservers.react.js

@@ -1,5 +1,5 @@
 import {connect} from 'react-redux';
-import {isEmpty} from 'ramda';
+import {append, isEmpty, lensPath, view} from 'ramda';
 import {notifyObservers, updateProps} from '../../actions';
 import React, {PropTypes} from 'react';
 
@@ -11,7 +11,8 @@ import React, {PropTypes} from 'react';
 function mapStateToProps (state) {
     return {
         dependencies: state.dependenciesRequest.content,
-        paths: state.paths
+        paths: state.paths,
+        layout: state.layout
     };
 }
 
@@ -33,6 +34,10 @@ function mergeProps(stateProps, dispatchProps, ownProps) {
         },
 
         setProps: function setProps(newProps) {
+            const itempath = stateProps.paths[ownProps.id];
+            const propPath = append('props', itempath);
+            const prevProps = view(lensPath(propPath), stateProps.layout);
+
             const payload = {
                 props: newProps,
                 id: ownProps.id,
@@ -43,7 +48,11 @@ function mergeProps(stateProps, dispatchProps, ownProps) {
             dispatch(updateProps(payload));
 
             // Update output components that depend on this input
-            dispatch(notifyObservers({id: ownProps.id, props: newProps}));
+            dispatch(notifyObservers({
+                id: ownProps.id,
+                props: newProps,
+                prevProps
+            }));
         }
     }