Creating ohif:metadata package with metadata classes and adding it to the viewers

Packages/ohif-metadata/client/OHIFInstanceMetadata.js

@@ -0,0 +1,58 @@
+import { Viewerbase } from 'meteor/ohif:viewerbase';
+
+const InstanceMetadata = Viewerbase.metadata.InstanceMetadata;
+
+export class OHIFInstanceMetadata extends InstanceMetadata {
+
+    /**
+     * @param {Object} Instance object.
+     */
+    constructor(data) {
+        super(data);
+        this.init();
+    }
+
+    init() {
+        const data = this.getData();
+        // set protected property...
+        this._sopInstanceUID = data.sopInstanceUid;
+    }
+
+    // Override
+    getRawValue(tagOrProperty, defaultValue) {
+        const propertyName = OHIFInstanceMetadata.getPropertyName(tagOrProperty);
+
+        const data = this.getData();
+        const rawValue = data[propertyName];
+
+        return rawValue !== void 0 ? rawValue : defaultValue;
+    }
+
+    // Override
+    tagExists(tagOrProperty) {
+        const propertyName = OHIFInstanceMetadata.getPropertyName(tagOrProperty);
+
+        const data = this.getData();
+
+        return (propertyName in data);
+    }
+
+    /**
+     * Static methods
+     */
+    
+    static getPropertyName(tagOrProperty) {
+        const tagInfo = InstanceMetadata.getTagInfo(tagOrProperty);
+
+        if(tagInfo.propertyName === null) {
+            return;
+        }
+
+        let propertyName = tagInfo.propertyName.charAt(0).toLowerCase() + tagInfo.propertyName.substr(1);
+        // TODO: Improve this: change retriveMetadata to use dicom standard names (see dicomTagDescriptions.js)
+        propertyName = propertyName.replace(/^sop/, 'SOP');
+        propertyName = propertyName.replace(/uid$/i, 'UID');
+
+        return propertyName;
+    }
+}