Exposed subscription API. Test coverage dropped below 90% as a result.

README.md

@@ -12,6 +12,8 @@ Support for `Date`, `RegExp` and `symbol` as part of keys. Support for `symbol`
 
 A powerful `db.find` function that supports approximate matching and works on both indexes and regular keys with over 50 operators including regular expressions, soundex/echoes, credit card, SSNs and more. If something is missing, it can be added in as little as one line.
 
+A subscription API allows listening for changes to the database.
+
 # Usage
 
 ```javascript
@@ -35,8 +37,6 @@ Primitive keys are automatically converted to the arrays required by Deno KV.
 
 Deno KV does not provide a `db.clear` function. Denodata does.
 
-```javascript
-
 ```javascript
 await db.set("mykey", "myvalue");
 await (async () => { const {key,value,version} = await db.get("mykey")})();
@@ -129,6 +129,12 @@ await (async () => {
     console.log(value); // prints Book instance, less efficient, large index scans because of lack of cname
   }
 })();
+db.subscribe({set: {key:1,value:1}},async (value) => {
+  console.log(value); // prints {key:1,value:1} so long as db.set(1,1) is called
+});
+db.subscribe({delete: (key) => key<10 ? key : undefined},async (value) => {
+  console.log(value); // prints key so long as db.delete(key) is called with value less than 10
+});
 ```
 
 # Installation
@@ -242,6 +248,11 @@ Notes:
 - Works like `Deno KV.set`. Does not manage indexes or do specialized serialization.
 - See notes at start of API section regarding `key` and `value` types.
 
+`db.subscribe(on:{delete?:any,patch?:any,put?:any,set?:any},callback:(arg1:any,arg2?:any)=>void,{cname?:string,metadata?:{[key:string]:any}}):void`
+
+- Calls the `callback` with the same signature as `db.delete`, `db.patch`, `db.put`, or `db.set` if the value or key and value in the `on` pattern, as well as `cname` and `metadata` match the call to `db.delete`, `db.patch`, `db.put`, or `db.set`.
+
+
 # Key and Value Space
 
 ## Keys
@@ -431,7 +442,7 @@ The following operators are supported in patterns.
 # Testing
 
 - `constants.js ... 100.000% (3/3)`
-- `denodata.ts ... index.js ...  90.196% (690/765)`
+- `denodata.ts ...  82.809% (684/826)`
 - `operators.ts ... ... 95.330% (347/364)`
 
 # Release History (Reverse Chronological Order)
@@ -440,6 +451,10 @@ The following operators are supported in patterns.
 - Beta  commenced when unit test coverage first exceeded 90%
 - The exposed API is stable. Additional features may be exposed.
 
+
+2023-08-09 v0.0.27 (Beta)
+  - Exposed subscription API. Test coverage dropped below 90% as a result.
+
 2023-07-28 v0.0.26 (Beta)
   - Documentation corrections.
 

package.json

@@ -1,7 +1,7 @@
 {
   "name": "denodata",
-  "version": "0.0.26",
-  "description": "Generalized indexing and search for Deno KV",
+  "version": "0.0.27",
+  "description": "Generalized indexing, search, and change subscriptions for Deno KV",
   "type": "module",
   "main": "mod.ts",
   "scripts": {

src/denodata.test.js

@@ -460,6 +460,70 @@ const test = async (deno) => {
         expect(sum.value.value).toEqual(1n);
     })
 
+    deno.test("subscribe delete", async (t) => {
+        return new Promise(async (resolve,reject) => {
+            await db.subscribe({delete: 1},(value) => {
+                try {
+                    expect(value).toEqual(1);
+                    resolve();
+                } catch(e) {
+                    reject(e);
+                }
+            });
+            await db.delete(1);
+        });
+    })
+
+    deno.test("subscribe delete - function test", async (t) => {
+        return new Promise(async (resolve,reject) => {
+            await db.subscribe({delete: (value) => value===1 ? value : undefined},(value) => {
+                try {
+                    expect(value).toEqual(1);
+                    resolve();
+                } catch(e) {
+                    reject(e);
+                }
+            });
+            await db.delete(1);
+        });
+    })
+
+    deno.test("subscribe set", async (t) => {
+       return new Promise(async (resolve,reject) => {
+           db.subscribe({set: {key:1,value:1}},async (key,value) => {
+               try {
+                     expect(key).toEqual(1);
+                     expect(value).toEqual(1);
+                     resolve();
+               } catch(e) {
+                   reject(e);
+               } finally {
+                   await db.delete(1);
+               }
+           });
+           await db.set(1,1);
+       });
+    })
+
+    deno.test("subscribe set - function test", async (t) => {
+        return new Promise(async (resolve,reject) => {
+            db.subscribe({set: {key:1,value:(value) => value===1 ? value : undefined}},async (key,value) => {
+                try {
+                    expect(key).toEqual(1);
+                    expect(value).toEqual(1);
+                    resolve();
+                } catch(e) {
+                    reject(e);
+                } finally {
+                    await db.delete(1);
+                }
+            });
+            await db.set(1,1);
+        });
+    })
+
+
+
     return async () => {
         const errors = [],
             start = Date.now();