Add database/collection/graph#exists

Author: pluma

docs/Drivers/JS/Reference/Collection/README.md

@@ -16,6 +16,21 @@ See
 [the HTTP API documentation](https://docs.arangodb.com/latest/HTTP/Collection/Getting.html)
 for details.
 
+## collection.exists
+
+`async collection.exists(): boolean`
+
+Checks whether the collection exists.
+
+**Examples**
+
+```js
+const db = new Database();
+const collection = db.collection('some-collection');
+const result = await collection.exists();
+// result indicates whether the collection exists
+```
+
 ### collection.get
 
 `async collection.get(): Object`
@@ -99,7 +114,7 @@ Retrieves the collection checksum.
 
 **Arguments**
 
-* **opts**: `Object` (optional)
+- **opts**: `Object` (optional)
 
   For information on the possible options see
   [the HTTP API for getting collection information](https://docs.arangodb.com/latest/HTTP/Collection/Getting.html).

docs/Drivers/JS/Reference/Database/DatabaseManipulation.md

@@ -166,6 +166,20 @@ const info = await db.createDatabase('mydb', [{username: 'root'}]);
 // the database has been created
 ```
 
+## database.exists
+
+`async database.exists(): boolean`
+
+Checks whether the database exists.
+
+**Examples**
+
+```js
+const db = new Database();
+const result = await db.exists();
+// result indicates whether the database exists
+```
+
 ## database.get
 
 `async database.get(): Object`

docs/Drivers/JS/Reference/Graph/README.md

@@ -3,6 +3,21 @@
 These functions implement the
 [HTTP API for manipulating graphs](https://docs.arangodb.com/latest/HTTP/Gharial/index.html).
 
+## graph.exists
+
+`async graph.exists(): boolean`
+
+Checks whether the graph exists.
+
+**Examples**
+
+```js
+const db = new Database();
+const graph = db.graph('some-graph');
+const result = await graph.exists();
+// result indicates whether the graph exists
+```
+
 ## graph.get
 
 `async graph.get(): Object`
@@ -27,7 +42,7 @@ the server response.
 
 **Arguments**
 
-* **properties**: `Object`
+- **properties**: `Object`
 
   For more information on the _properties_ object, see
   [the HTTP API documentation for creating graphs](https://docs.arangodb.com/latest/HTTP/Gharial/Management.html).
@@ -55,7 +70,7 @@ Deletes the graph from the database.
 
 **Arguments**
 
-* **dropCollections**: `boolean` (optional)
+- **dropCollections**: `boolean` (optional)
 
   If set to `true`, the collections associated with the graph will also be
   deleted.

src/collection.ts

@@ -1,6 +1,5 @@
 import { Connection } from "./connection";
 import { ArrayCursor } from "./cursor";
-import { ArangoError } from "./error";
 
 export enum Types {
   DOCUMENT_COLLECTION = 2,
@@ -31,6 +30,7 @@ export interface ArangoCollection {
   name: string;
 }
 
+const COLLECTION_NOT_FOUND = 1203;
 export abstract class BaseCollection implements ArangoCollection {
   isArangoCollection: true = true;
   name: string;
@@ -108,12 +108,15 @@ export abstract class BaseCollection implements ArangoCollection {
   }
 
   exists(): Promise<boolean> {
-    return this._connection
-      .request({ path: `/_api/collection/${this.name}` }, () => true)
-      .catch((e: ArangoError) => {
-        if (e.errorNum !== 1203) throw e;
+    return this.get().then(
+      () => true,
+      err => {
+        if (err.errorNum !== COLLECTION_NOT_FOUND) {
+          throw err;
+        }
         return false;
-      });
+      }
+    );
   }
 
   create(properties?: any) {

src/database.ts

@@ -1,13 +1,18 @@
 import { AqlLiteral, AqlQuery, isAqlLiteral, isAqlQuery } from "./aql-query";
-import { ArangoCollection, constructCollection, DocumentCollection, EdgeCollection, isArangoCollection } from "./collection";
+import {
+  ArangoCollection,
+  constructCollection,
+  DocumentCollection,
+  EdgeCollection,
+  isArangoCollection
+} from "./collection";
 import { Config, Connection } from "./connection";
 import { ArrayCursor } from "./cursor";
 import { Graph } from "./graph";
 import { Route } from "./route";
 import { btoa } from "./util/btoa";
 import { toForm } from "./util/multipart";
 
-
 function colToString(collection: string | ArangoCollection): string {
   if (isArangoCollection(collection)) {
     return String(collection.name);
@@ -37,6 +42,7 @@ export type ServiceOptions = {
   dependencies?: { [key: string]: any };
 };
 
+const DATABASE_NOT_FOUND = 1228;
 export class Database {
   private _connection: Connection;
 
@@ -91,6 +97,18 @@ export class Database {
     );
   }
 
+  exists(): Promise<boolean> {
+    return this.get().then(
+      () => true,
+      err => {
+        if (err.errorNum !== DATABASE_NOT_FOUND) {
+          throw err;
+        }
+        return false;
+      }
+    );
+  }
+
   createDatabase(databaseName: string, users?: string[]) {
     return this._connection.request(
       {
@@ -687,7 +705,7 @@ export class Database {
     );
   }
 
-  login(username: string = 'root', password: string = ''): Promise<string> {
+  login(username: string = "root", password: string = ""): Promise<string> {
     return this._connection.request(
       {
         method: "POST",

src/graph.ts

@@ -3,10 +3,9 @@ import {
   BaseCollection,
   DocumentHandle,
   EdgeCollection,
-  Types,
-  isArangoCollection
+  isArangoCollection,
+  Types
 } from "./collection";
-
 import { Connection } from "./connection";
 
 export class GraphVertexCollection extends BaseCollection {
@@ -244,6 +243,7 @@ export class GraphEdgeCollection extends EdgeCollection {
   }
 }
 
+const GRAPH_NOT_FOUND = 1924;
 export class Graph {
   name: string;
 
@@ -261,6 +261,18 @@ export class Graph {
     );
   }
 
+  exists(): Promise<boolean> {
+    return this.get().then(
+      () => true,
+      err => {
+        if (err.errorNum !== GRAPH_NOT_FOUND) {
+          throw err;
+        }
+        return false;
+      }
+    );
+  }
+
   create(properties: any = {}, opts?: { waitForSync?: boolean }) {
     return this._connection.request(
       {