Hook Reference

Hooks allow plugins to intercept and modify EmDash behavior at specific points in the content, media, email, comment, and page lifecycle.

Hook Overview

Hook	Trigger	Can Modify	Exclusive
`content:beforeSave`	Before content is saved	Content data	No
`content:afterSave`	After content is saved	Nothing	No
`content:beforeDelete`	Before content is deleted	Can cancel	No
`content:afterDelete`	After content is deleted	Nothing	No
`media:beforeUpload`	Before file is uploaded	File metadata	No
`media:afterUpload`	After file is uploaded	Nothing	No
`cron`	Scheduled task fires	Nothing	No
`email:beforeSend`	Before email delivery	Message, can cancel	No
`email:deliver`	Deliver email via transport	Nothing	Yes
`email:afterSend`	After successful email delivery	Nothing	No
`comment:beforeCreate`	Before comment is stored	Comment, can cancel	No
`comment:moderate`	Decide comment approval status	Status	Yes
`comment:afterCreate`	After comment is stored	Nothing	No
`comment:afterModerate`	After admin changes comment status	Nothing	No
`page:metadata`	Rendering public page head	Contribute tags	No
`page:fragments`	Rendering public page body	Inject scripts	No
`plugin:install`	When plugin is first installed	Nothing	No
`plugin:activate`	When plugin is enabled	Nothing	No
`plugin:deactivate`	When plugin is disabled	Nothing	No
`plugin:uninstall`	When plugin is removed	Nothing	No

Content Hooks

`content:beforeSave`

Runs before content is saved to the database. Use to validate, transform, or enrich content.

import { definePlugin } from "emdash";

export default definePlugin({
  id: "my-plugin",
  version: "1.0.0",
  hooks: {
    "content:beforeSave": async (event, ctx) => {
      const { content, collection, isNew } = event;

      // Add timestamps
      if (isNew) {
        content.createdBy = "system";
      }
      content.modifiedAt = new Date().toISOString();

      // Return modified content
      return content;
    },
  },
});

Event

interface ContentHookEvent {
  content: Record<string, unknown>; // Content data
  collection: string; // Collection slug
  isNew: boolean; // True for creates, false for updates
}

Return Value

Return modified content object to apply changes
Return void to pass through unchanged

`content:afterSave`

Runs after content is saved. Use for side effects like notifications, cache invalidation, or external syncing.

hooks: {
  "content:afterSave": async (event, ctx) => {
    const { content, collection, isNew } = event;

    if (collection === "posts" && content.status === "published") {
      // Notify external service
      await ctx.http?.fetch("https://api.example.com/notify", {
        method: "POST",
        body: JSON.stringify({ postId: content.id }),
      });
    }
  },
}

Return Value

No return value expected.

`content:beforeDelete`

Runs before content is deleted. Use to validate deletion or prevent it.

hooks: {
  "content:beforeDelete": async (event, ctx) => {
    const { id, collection } = event;

    // Prevent deletion of protected content
    const item = await ctx.content?.get(collection, id);
    if (item?.data.protected) {
      return false; // Cancel deletion
    }

    // Allow deletion
    return true;
  },
}

Event

interface ContentDeleteEvent {
  id: string; // Entry ID
  collection: string; // Collection slug
}

Return Value

Return false to cancel deletion
Return true or void to allow

`content:afterDelete`

Runs after content is deleted. Use for cleanup tasks.

hooks: {
  "content:afterDelete": async (event, ctx) => {
    const { id, collection } = event;

    // Clean up related data
    await ctx.storage.relatedItems.delete(`${collection}:${id}`);
  },
}

Media Hooks

`media:beforeUpload`

Runs before a file is uploaded. Use to validate, rename, or reject files.

hooks: {
  "media:beforeUpload": async (event, ctx) => {
    const { file } = event;

    // Reject files over 10MB
    if (file.size > 10 * 1024 * 1024) {
      throw new Error("File too large");
    }

    // Rename file
    return {
      name: `${Date.now()}-${file.name}`,
      type: file.type,
      size: file.size,
    };
  },
}

Event

interface MediaUploadEvent {
  file: {
    name: string; // Original filename
    type: string; // MIME type
    size: number; // Size in bytes
  };
}

Return Value

Return modified file metadata to apply changes
Return void to pass through unchanged
Throw to reject the upload

`media:afterUpload`

Runs after a file is uploaded. Use for processing, thumbnails, or metadata extraction.

hooks: {
  "media:afterUpload": async (event, ctx) => {
    const { media } = event;

    if (media.mimeType.startsWith("image/")) {
      // Store image metadata
      await ctx.kv.set(`media:${media.id}:analyzed`, {
        processedAt: new Date().toISOString(),
      });
    }
  },
}

Event

interface MediaAfterUploadEvent {
  media: {
    id: string;
    filename: string;
    mimeType: string;
    size: number | null;
    url: string;
    createdAt: string;
  };
}

Lifecycle Hooks

`plugin:install`

Runs when a plugin is first installed. Use for initial setup, creating storage collections, or seeding data.

hooks: {
  "plugin:install": async (event, ctx) => {
    // Initialize default settings
    await ctx.kv.set("settings:enabled", true);
    await ctx.kv.set("settings:threshold", 100);

    ctx.log.info("Plugin installed successfully");
  },
}

`plugin:activate`

Runs when a plugin is enabled (after install or re-enable).

hooks: {
  "plugin:activate": async (event, ctx) => {
    ctx.log.info("Plugin activated");
  },
}

`plugin:deactivate`

Runs when a plugin is disabled.

hooks: {
  "plugin:deactivate": async (event, ctx) => {
    ctx.log.info("Plugin deactivated");
  },
}

`plugin:uninstall`

Runs when a plugin is removed. Use for cleanup.

hooks: {
  "plugin:uninstall": async (event, ctx) => {
    const { deleteData } = event;

    if (deleteData) {
      // Clean up all plugin data
      const items = await ctx.kv.list("settings:");
      for (const { key } of items) {
        await ctx.kv.delete(key);
      }
    }

    ctx.log.info("Plugin uninstalled");
  },
}

Event

interface UninstallEvent {
  deleteData: boolean; // User chose to delete data
}

Cron Hook

`cron`

Fired when a scheduled task executes. Schedule tasks with ctx.cron.schedule().

hooks: {
  "cron": async (event, ctx) => {
    if (event.name === "daily-sync") {
      const data = await ctx.http?.fetch("https://api.example.com/data");
      ctx.log.info("Sync complete");
    }
  },
}

Event

interface CronEvent {
  name: string;
  data?: Record<string, unknown>;
  scheduledAt: string;
}

Email Hooks

Email hooks form a pipeline: email:beforeSend → email:deliver → email:afterSend.

`email:beforeSend`

Capability: email:intercept

Middleware hook that runs before delivery. Transform messages or cancel delivery.

hooks: {
  "email:beforeSend": async (event, ctx) => {
    // Add footer to all emails
    return {
      ...event.message,
      text: event.message.text + "\n\n—Sent from My Site",
    };

    // Or return false to cancel delivery
  },
}

Event

interface EmailBeforeSendEvent {
  message: { to: string; subject: string; text: string; html?: string };
  source: string;
}

Return Value

Return modified message to transform
Return false to cancel delivery
Return void to pass through unchanged

`email:deliver`

Capability: email:provide | Exclusive: Yes

The transport provider. Only one plugin can deliver emails. Responsible for actually sending the message via an email service.

hooks: {
  "email:deliver": {
    exclusive: true,
    handler: async (event, ctx) => {
      await sendViaSES(event.message);
    },
  },
}

`email:afterSend`

Capability: email:intercept

Fire-and-forget hook after successful delivery. Errors are logged but do not propagate.

hooks: {
  "email:afterSend": async (event, ctx) => {
    await ctx.kv.set(`email:log:${Date.now()}`, {
      to: event.message.to,
      subject: event.message.subject,
    });
  },
}

Comment Hooks

Comment hooks form a pipeline: comment:beforeCreate → comment:moderate → comment:afterCreate. The comment:afterModerate hook fires separately when an admin changes a comment’s status.

`comment:beforeCreate`

Capability: read:users

Middleware hook before a comment is stored. Enrich, validate, or reject comments.

hooks: {
  "comment:beforeCreate": async (event, ctx) => {
    // Reject comments with links
    if (event.comment.body.includes("http")) {
      return false;
    }
  },
}

Event

interface CommentBeforeCreateEvent {
  comment: {
    collection: string;
    contentId: string;
    parentId: string | null;
    authorName: string;
    authorEmail: string;
    authorUserId: string | null;
    body: string;
    ipHash: string | null;
    userAgent: string | null;
  };
  metadata: Record<string, unknown>;
}

Return Value

Return modified event to transform
Return false to reject
Return void to pass through

`comment:moderate`

Capability: read:users | Exclusive: Yes

Decide whether a comment is approved, pending, or spam. Only one moderation provider is active.

hooks: {
  "comment:moderate": {
    exclusive: true,
    handler: async (event, ctx) => {
      const score = await checkSpam(event.comment);
      return {
        status: score > 0.8 ? "spam" : score > 0.5 ? "pending" : "approved",
        reason: `Spam score: ${score}`,
      };
    },
  },
}

Event

interface CommentModerateEvent {
  comment: { /* same as beforeCreate */ };
  metadata: Record<string, unknown>;
  collectionSettings: {
    commentsEnabled: boolean;
    commentsModeration: "all" | "first_time" | "none";
    commentsClosedAfterDays: number;
    commentsAutoApproveUsers: boolean;
  };
  priorApprovedCount: number;
}

Return Value

{ status: "approved" | "pending" | "spam"; reason?: string }

`comment:afterCreate`

Capability: read:users

Fire-and-forget hook after a comment is stored. Use for notifications.

hooks: {
  "comment:afterCreate": async (event, ctx) => {
    if (event.comment.status === "approved") {
      await ctx.email?.send({
        to: event.contentAuthor?.email,
        subject: `New comment on "${event.content.title}"`,
        text: `${event.comment.authorName} commented: ${event.comment.body}`,
      });
    }
  },
}

`comment:afterModerate`

Capability: read:users

Fire-and-forget hook when an admin manually changes a comment’s status.

Event

interface CommentAfterModerateEvent {
  comment: { id: string; /* ... */ };
  previousStatus: string;
  newStatus: string;
  moderator: { id: string; name: string | null };
}

Page Hooks

Page hooks run when rendering public pages. They allow plugins to inject metadata and scripts.

`page:metadata`

Capability: page:inject

Contribute meta tags, Open Graph properties, JSON-LD structured data, or link tags to the page head.

hooks: {
  "page:metadata": async (event, ctx) => {
    return [
      { kind: "meta", name: "generator", content: "EmDash" },
      { kind: "property", property: "og:site_name", content: event.page.siteName },
      { kind: "jsonld", graph: { "@type": "WebSite", name: event.page.siteName } },
    ];
  },
}

Contribution Types

type PageMetadataContribution =
  | { kind: "meta"; name: string; content: string; key?: string }
  | { kind: "property"; property: string; content: string; key?: string }
  | { kind: "link"; rel: string; href: string; hreflang?: string; key?: string }
  | { kind: "jsonld"; id?: string; graph: Record<string, unknown> };

The key field deduplicates contributions — only the last contribution with a given key is used.

`page:fragments`

Capability: page:inject

Inject scripts or HTML into pages. Only available to trusted (native) plugins.

hooks: {
  "page:fragments": async (event, ctx) => {
    return [
      {
        kind: "external-script",
        placement: "body:end",
        src: "https://analytics.example.com/script.js",
        async: true,
      },
      {
        kind: "inline-script",
        placement: "head",
        code: `window.siteId = "abc123";`,
      },
    ];
  },
}

Contribution Types

type PageFragmentContribution =
  | {
      kind: "external-script";
      placement: "head" | "body:start" | "body:end";
      src: string;
      async?: boolean;
      defer?: boolean;
      attributes?: Record<string, string>;
      key?: string;
    }
  | {
      kind: "inline-script";
      placement: "head" | "body:start" | "body:end";
      code: string;
      attributes?: Record<string, string>;
      key?: string;
    }
  | {
      kind: "html";
      placement: "head" | "body:start" | "body:end";
      html: string;
      key?: string;
    };

Hook Configuration

Hooks accept either a handler function or a configuration object:

hooks: {
  // Simple handler
  "content:afterSave": async (event, ctx) => { ... },

  // With configuration
  "content:beforeSave": {
    priority: 50,        // Lower runs first (default: 100)
    timeout: 10000,      // Max execution time in ms (default: 5000)
    dependencies: [],    // Run after these plugins
    errorPolicy: "abort", // "continue" or "abort" (default)
    handler: async (event, ctx) => { ... },
  },
}

Configuration Options

Option	Type	Default	Description
`priority`	`number`	`100`	Execution order (lower = earlier)
`timeout`	`number`	`5000`	Max execution time in milliseconds
`dependencies`	`string[]`	`[]`	Plugin IDs that must run first
`errorPolicy`	`string`	`"abort"`	`"continue"` to ignore errors
`exclusive`	`boolean`	`false`	Only one plugin can be the active provider (for provider-pattern hooks like `email:deliver`, `comment:moderate`)

Plugin Context

All hooks receive a context object with access to plugin APIs:

interface PluginContext {
  plugin: { id: string; version: string };
  storage: PluginStorage;
  kv: KVAccess;
  content?: ContentAccess;
  media?: MediaAccess;
  http?: HttpAccess;
  log: LogAccess;
  site: { name: string; url: string; locale: string };
  url(path: string): string;
  users?: UserAccess;
  cron?: CronAccess;
  email?: EmailAccess;
}

See Plugin Overview — Plugin Context for capability requirements and method details.

Error Handling

Errors in hooks are logged and handled based on errorPolicy:

"abort" (default) — Stop execution, rollback transaction if applicable
"continue" — Log error and continue to next hook

hooks: {
  "content:beforeSave": {
    errorPolicy: "continue", // Don't block save if this fails
    handler: async (event, ctx) => {
      try {
        await ctx.http?.fetch("https://api.example.com/validate");
      } catch (error) {
        ctx.log.warn("Validation service unavailable", error);
      }
    },
  },
}

Execution Order

Hooks run in this order:

Sorted by priority (ascending)
Plugins with dependencies run after their dependencies
Within same priority, order is deterministic but unspecified

// This runs first (priority 10)
{ priority: 10, handler: ... }

// This runs second (priority 50)
{ priority: 50, handler: ... }

// This runs last (default priority 100)
{ handler: ... }