[feature][s]:support queries by frontmatter fields

.changeset/five-melons-pull.md

@@ -0,0 +1,5 @@
+---
+"mddb": minor
+---
+
+Support for querying files by frontmatter field values (exact matches only).

__mocks__/content/blog/blog1.mdx

@@ -1,5 +1,7 @@
 ---
 title: My Test Mdx Blog 1
+author: John Doe
+draft: true
 ---
 
 # My Test Mdx Blog 1

__mocks__/content/blog/blog2.mdx

@@ -1,6 +1,7 @@
 ---
 title: My Test Mdx Blog 2
 type: blog
+author: John Doe
 tags:
   - economy
 ---

__mocks__/content/blog/blog3.mdx

@@ -1,6 +1,8 @@
 ---
 title: My Test Mdx Blog 2
 type: blog
+author: Jan Kowalski
+draft: true
 tags:
   - politics
   - economy

src/lib/markdowndb.spec.ts

@@ -110,6 +110,51 @@ describe("MarkdownDB - default config", () => {
       });
     });
 
+    test("can query by a frontmatter field", async () => {
+      const dbFiles = await mddb.getFiles({
+        frontmatter: { author: "John Doe" },
+      });
+      const dbFilesPaths = dbFiles.map((f) => f.file_path);
+
+      const expectedPaths = [
+        `${pathToContentFixture}/blog/blog1.mdx`,
+        `${pathToContentFixture}/blog/blog2.mdx`,
+      ];
+
+      expect(dbFilesPaths).toHaveLength(expectedPaths.length);
+      dbFilesPaths.forEach((p) => {
+        expect(expectedPaths).toContain(p);
+      });
+    });
+
+    test("can query by multiple frontmatter fields", async () => {
+      const dbFiles = await mddb.getFiles({
+        frontmatter: { author: "John Doe", draft: true },
+      });
+      const dbFilesPaths = dbFiles.map((f) => f.file_path);
+
+      const expectedPaths = [`${pathToContentFixture}/blog/blog1.mdx`];
+
+      expect(dbFilesPaths).toHaveLength(expectedPaths.length);
+      dbFilesPaths.forEach((p) => {
+        expect(expectedPaths).toContain(p);
+      });
+    });
+
+    test("can get records with non-existing field for `false` queries", async () => {
+      const dbFiles = await mddb.getFiles({
+        frontmatter: { author: "John Doe", draft: false },
+      });
+      const dbFilesPaths = dbFiles.map((f) => f.file_path);
+
+      const expectedPaths = [`${pathToContentFixture}/blog/blog2.mdx`];
+
+      expect(dbFilesPaths).toHaveLength(expectedPaths.length);
+      dbFilesPaths.forEach((p) => {
+        expect(expectedPaths).toContain(p);
+      });
+    });
+
     test("can query by tags AND filetypes AND extensions", async () => {
       const dbFiles = await mddb.getFiles({
         tags: ["culture"],

src/lib/markdowndb.ts

@@ -238,8 +238,9 @@ export class MarkdownDB {
     filetypes?: string[];
     tags?: string[];
     extensions?: string[];
+    frontmatter?: Record<string, string | number | boolean>;
   }): Promise<MddbFile[]> {
-    const { filetypes, tags, extensions, folder } = query || {};
+    const { filetypes, tags, extensions, folder, frontmatter } = query || {};
 
     const files = await this.db
       // TODO join only if tags are specified ?
@@ -260,6 +261,34 @@ export class MarkdownDB {
         if (filetypes) {
           builder.whereIn("filetype", filetypes);
         }
+
+        if (frontmatter) {
+          Object.entries(frontmatter).forEach(([key, value]) => {
+            if (typeof value === "string" || typeof value === "number") {
+              builder.whereRaw(`json_extract(metadata, '$.${key}') = ?`, [
+                value,
+              ]);
+            } else if (typeof value === "boolean") {
+              if (value) {
+                builder.whereRaw(`json_extract(metadata, '$.${key}') = ?`, [
+                  true,
+                ]);
+              } else {
+                builder.where(function () {
+                  this.whereRaw(`json_extract(metadata, '$.${key}') = ?`, [
+                    false,
+                  ]).orWhereRaw(`json_extract(metadata, '$.${key}') IS NULL`);
+                });
+              }
+            }
+            // To check if the provided value exists in an array inside the JSON
+            else {
+              builder.whereRaw(`json_extract(metadata, '$.${key}') LIKE ?`, [
+                `%${value}%`,
+              ]);
+            }
+          });
+        }
       })
       .select("files.*")
       .from("files")