[#54 Computed Fields] (#86)

* Computed Fields

* Make configuration optional

* Add changeset for computed fields

* Update changeset

.changeset/flat-bikes-own.md

@@ -0,0 +1,6 @@
+---
+"mddb": minor
+---
+
+[#54 Computed Fields]
+- Introduce a configuration parameter to support the inclusion of a custom function for computing fields.

README.md

@@ -115,18 +115,49 @@ const blogs = await mddb.getFiles({
 });
 ```
 
-# Configuring `markdowndb.config.js`
+## Computed Fields
+
+This feature helps you define functions that compute additional fields you want to include.
+
+### Step 1: Define the Computed Field Function
+
+Next, define a function that computes the additional field you want to include. In this example, we have a function named `addTitle` that extracts the title from the first heading in the AST (Abstract Syntax Tree) of a Markdown file.
+
+```javascript
+const addTitle = (fileInfo, ast) => {
+  // Find the first header node in the AST
+  const headerNode = ast.children.find((node) => node.type === "heading");
+
+  // Extract the text content from the header node
+  const title = headerNode
+    ? headerNode.children.map((child) => child.value).join("")
+    : "";
+
+  // Add the title property to the fileInfo
+  fileInfo.title = title;
+};
+```
+
+### Step 2: Indexing the Folder with Computed Fields
+
+Now, use the `client.indexFolder` method to scan and index the folder containing your Markdown files. Pass the `addTitle` function in the `computedFields` option array to include the computed title in the database.
+
+```javascript
+client.indexFolder(folderPath: "PATH_TO_FOLDER", customConfig: { computedFields: [addTitle] });
+```
+
+## Configuring `markdowndb.config.js`
 
 - Implement computed fields to dynamically calculate values based on specified logic or dependencies.
 - Specify the patterns for including or excluding files in MarkdownDB.
 
-## Example Configuration
+### Example Configuration
 
 Here's an example `markdowndb.config.js` with custom configurations:
 
 ```javascript
 export default {
-  customFields: [
+  computedFields: [
     (fileInfo, ast) => {
       // Your custom logic here
     },

src/lib/CustomConfig.ts

@@ -0,0 +1,6 @@
+import { FileInfo } from "./process.js";
+import { Root } from "remark-parse/lib/index.js";
+
+export interface CustomConfig {
+  computedFields?: ((fileInfo: FileInfo, ast: Root) => any)[];
+}

src/lib/indexFolder.ts

@@ -1,22 +1,26 @@
+import { CustomConfig } from "./CustomConfig.js";
 import { FileInfo, processFile } from "./process.js";
 import { recursiveWalkDir } from "./recursiveWalkDir.js";
 
 export function indexFolder(
   folderPath: string,
   pathToUrlResolver: (filePath: string) => string,
+  config: CustomConfig,
   ignorePatterns?: RegExp[]
 ) {
   const filePathsToIndex = recursiveWalkDir(folderPath);
   const filteredFilePathsToIndex = filePathsToIndex.filter((filePath) =>
     shouldIncludeFile(filePath, ignorePatterns)
   );
   const files: FileInfo[] = [];
+  const computedFields = config.computedFields || [];
   for (const filePath of filteredFilePathsToIndex) {
     const fileObject = processFile(
       folderPath,
       filePath,
       pathToUrlResolver,
-      filePathsToIndex
+      filePathsToIndex,
+      computedFields
     );
     files.push(fileObject);
   }

src/lib/markdowndb.ts

@@ -12,6 +12,7 @@ import {
   getUniqueValues,
 } from "./databaseUtils.js";
 import fs from "fs";
+import { CustomConfig } from "./CustomConfig.js";
 
 const defaultFilePathToUrl = (filePath: string) => {
   let url = filePath
@@ -72,16 +73,19 @@ export class MarkdownDB {
     // TODO support glob patterns
     ignorePatterns = [],
     pathToUrlResolver = defaultFilePathToUrl,
+    customConfig = {},
   }: {
     folderPath: string;
     ignorePatterns?: RegExp[];
     pathToUrlResolver?: (filePath: string) => string;
+    customConfig?: CustomConfig;
   }) {
     await resetDatabaseTables(this.db);
 
     const fileObjects = indexFolder(
       folderPath,
       pathToUrlResolver,
+      customConfig,
       ignorePatterns
     );
     const filesToInsert = fileObjects.map(mapFileToInsert);

src/lib/parseFile.ts

@@ -28,6 +28,7 @@ export function parseFile(source: string, options?: ParsingOptions) {
   metadata.tasks = tasks;
 
   return {
+    ast,
     metadata,
     links,
   };

src/lib/process.ts

@@ -4,6 +4,7 @@ import path from "path";
 
 import { File } from "./schema.js";
 import { WikiLink, parseFile } from "./parseFile.js";
+import { Root } from "remark-parse/lib/index.js";
 
 export interface FileInfo extends File {
   tags: string[];
@@ -16,7 +17,8 @@ export function processFile(
   rootFolder: string,
   filePath: string,
   pathToUrlResolver: (filePath: string) => string,
-  filePathsToIndex: string[]
+  filePathsToIndex: string[],
+  computedFields: ((fileInfo: FileInfo, ast: Root) => any)[]
 ) {
   // Remove rootFolder from filePath
   const relativePath = path.relative(rootFolder, filePath);
@@ -52,7 +54,7 @@ export function processFile(
     flag: "r",
   });
 
-  const { metadata, links } = parseFile(source, {
+  const { ast, metadata, links } = parseFile(source, {
     from: relativePath,
     permalinks: filePathsToIndex,
   });
@@ -66,6 +68,10 @@ export function processFile(
 
   const tags = metadata?.tags || [];
   fileInfo.tags = tags;
+  for (let index = 0; index < computedFields.length; index++) {
+    const customFieldFunction = computedFields[index];
+    customFieldFunction(fileInfo, ast);
+  }
 
   return fileInfo;
 }

src/tests/process.spec.ts

@@ -11,6 +11,7 @@ describe("Can parse a file and get file info", () => {
       pathToContentFixture,
       fullPath,
       (filePath) => filePath,
+      [],
       []
     );