Add parseTemplate function. V 0.2

README.md

@@ -49,7 +49,8 @@ The following functions and variables are defined:
 | `window.cardTools.createEntityRow(config)` | 0.1 | Creates and sets up an `entities` row based on `config` |
 | `window.cardTools.deviceID` | 0.1 | Kind of unique and kind of persistent identifier for the browser viewing the page |
 | `window.cardTools.moreInfo(entity)` | 0.1 | Brings up the `more-info` dialog for the specified `entity` id |
-| `window.cardTools.longPress(element)` | 0.1 | Bind `element` to the long-press handler of lovelace. |
+| `window.cardTools.longPress(element)` | 0.1 | Bind `element` to the long-press handler of lovelace |
+| `window.cardTools.parseTemplate(str)` | 0.2 | Parse a simple state template and return results |
 
 > Another way to use the `card-tools` is to just copy the function you want, and paste it into your card. It requires a bit of more work, but may be more user friendly.
 
@@ -178,3 +179,25 @@ firstUpdated() {
   window.cardTools.longpress(this.shadowRoot.querySelector('paper-button'));
 }
 ```
+
+### parseTemplate
+
+This lets you parse a user specified template like `[[ light.bed_light.state ]]` and return the result.
+
+Two things are important:
+
+- The template must start with `[[<space>` and end with `<space>]]`
+- This is not in any way the same kind of template as used in the Home Assistant configuration
+
+The templates are parsed by reading one step at a time from the `hass.states` object.
+Thus, the first part must be an entity with domain and id, e.g. `light.bed_light`, `media_player.bedroom` etc.
+Next is one of:
+
+- `entity_id`
+- `state`
+- `attributes.<attribute>`
+- `last_changed`
+- `last_updated`
+
+If the string does not match the template format, the original string is returned.
+Otherwise the requested value is returned, or an error message on failure.

card-tools.js

@@ -1,5 +1,5 @@
 if (!window.cardTools){
-  const version = 0.1;
+  const version = 0.2;
   const CUSTOM_TYPE_PREFIX = "custom:";
 
   let cardTools =
@@ -177,6 +177,23 @@ if (!window.cardTools){
       return element;
     };
 
+  cardTools.parseTemplate =
+    (str) => {
+      if(!str || !str.startsWith('[[ ') || !str.endsWith(' ]]'))
+        return str;
+      try {
+        str = str.replace(/^\[\[\s+|\s+\]\]$/g, '')
+        const parts = str.split(".");
+        let v = cardTools.hass.states[`${parts[0]}.${parts[1]}`];
+        parts.shift();
+        parts.shift();
+        parts.forEach(item => v = v[item]);
+        return v;
+      } catch {
+        return `[[ Template matching failed ${str} ]]`;
+      }
+    }
+
   window.cardTools = cardTools;
   cardTools.fireEvent("rebuild-view");
 }