Merge pull request #228 from terminusdb/has_db

Add hasDatabase function for checking DB exist

Author: GavinMendelGleason

docs/api/woqlclient.md

@@ -338,6 +338,29 @@ name the databases list will be set to empty
 client.organization("admin")
 ```
 
+## hasDatabase
+##### woqlClient.hasDatabase([orgName], [dbName]) ⇒ <code>Promise</code>
+Checks if a database exists
+
+Returns true if a DB exists and false if it doesn't. Other results
+throw an exception.
+
+
+| Param | Type | Description |
+| --- | --- | --- |
+| [orgName] | <code>string</code> | the organization id to set the context to |
+| [dbName] | <code>string</code> | the db name to set the context to |
+
+**Example**  
+```javascript
+async function executeIfDatabaseExists(f){
+     const hasDB = await client.hasDatabase("admin", "testdb")
+     if (hasDB) {
+         f()
+     }
+}
+```
+
 ## getDatabases
 ##### woqlClient.getDatabases() ⇒ <code>Promise</code>
 Gets the organization's databases list.

lib/woqlClient.js

@@ -142,6 +142,37 @@ WOQLClient.prototype.organization = function (orgId) {
   return this.connectionConfig.organization();
 };
 
+/**
+ * Checks if a database exists
+ *
+ * Returns true if a DB exists and false if it doesn't. Other results
+ * throw an exception.
+ * @param {string} [orgName] the organization id to set the context to
+ * @param {string} [dbName] the db name to set the context to
+ * @returns {Promise}
+ * @example
+ * async function executeIfDatabaseExists(f){
+ *      const hasDB = await client.hasDatabase("admin", "testdb")
+ *      if (hasDB) {
+ *          f()
+ *      }
+ * }
+ */
+WOQLClient.prototype.hasDatabase = async function (orgName, dbName) {
+  const dbCheckUrl = `${this.connectionConfig.apiURL()}db/${orgName}/${dbName}`;
+  return new Promise((resolve, reject) => {
+    this.dispatch(CONST.HEAD, dbCheckUrl).then((req) => {
+      resolve(true);
+    }).catch((err) => {
+      if (err.status === 404) {
+        resolve(false);
+      } else {
+        reject(err);
+      }
+    });
+  });
+};
+
 /**
  * Gets the organization's databases list.
  *