Explore: Add history to query fields

- queries are saved to localstorage history array
- one history per datasource type (plugin ID)
- 100 items kept with timestamps
- history suggestions can be pulled up with Ctrl-SPACE

public/app/core/specs/store.jest.ts

@@ -32,6 +32,18 @@ describe('store', () => {
     expect(store.getBool('key5', false)).toBe(true);
   });
 
+  it('gets an object', () => {
+    expect(store.getObject('object1')).toBeUndefined();
+    expect(store.getObject('object1', [])).toEqual([]);
+    store.setObject('object1', [1]);
+    expect(store.getObject('object1')).toEqual([1]);
+  });
+
+  it('sets an object', () => {
+    expect(store.setObject('object2', { a: 1 })).toBe(true);
+    expect(store.getObject('object2')).toEqual({ a: 1 });
+  });
+
   it('key should be deleted', () => {
     store.set('key6', '123');
     store.delete('key6');

public/app/core/store.ts

@@ -14,6 +14,38 @@ export class Store {
     return window.localStorage[key] === 'true';
   }
 
+  getObject(key: string, def?: any) {
+    let ret = def;
+    if (this.exists(key)) {
+      const json = window.localStorage[key];
+      try {
+        ret = JSON.parse(json);
+      } catch (error) {
+        console.error(`Error parsing store object: ${key}. Returning default: ${def}. [${error}]`);
+      }
+    }
+    return ret;
+  }
+
+  // Returns true when successfully stored
+  setObject(key: string, value: any): boolean {
+    let json;
+    try {
+      json = JSON.stringify(value);
+    } catch (error) {
+      console.error(`Could not stringify object: ${key}. [${error}]`);
+      return false;
+    }
+    try {
+      this.set(key, json);
+    } catch (error) {
+      // Likely hitting storage quota
+      console.error(`Could not save item in localStorage: ${key}. [${error}]`);
+      return false;
+    }
+    return true;
+  }
+
   exists(key) {
     return window.localStorage[key] !== void 0;
   }