sync-gateway-config.json

{
  "interface":":4984",
  "log": ["HTTP", "Auth"],
  "databases": {
    "todo": {
      "server": "walrus:",
      "bucket": "todo",
      "users": {
        "user1": {"password": "pass", "admin_channels": ["user1"]},
        "user2": {"password": "pass", "admin_channels": ["user2"]},
        "mod": {"password": "pass", "admin_roles": ["moderator"]},
        "admin": {"password": "pass", "admin_roles": ["admin"]}
      },
      "roles": {
        "moderator": {},
        "admin": {}
      },
      "sync": `
function(doc, oldDoc){
  /* Type validation */
  if (isCreate()) {
    // Don't allow creating a document without a type.
    validateNotEmpty("type", doc.type);
  } else if (isUpdate()) {
    // Don't allow changing the type of any document.
    validateReadOnly("type", doc.type, oldDoc.type);
  }

  if (getType() == "moderator") {
    /* Control Write Access */
    // Only allow admins to add/remove moderators.
    requireRole("admin");

    /* Validate */
    if (!isDelete()) {
      // Validate required fields.
      validateNotEmpty("username", doc.username);

      if (isCreate()) {
        // We use a key pattern to ensure unique moderators within the system, 
        // so we need to ensure that doc._id matches the pattern
        // moderator.{username}.
        if (doc._id != "moderator." + doc.username) {
          throw({forbidden: "_id must match the pattern moderator.{username}."});
        }
      } else {
        // doc._id is tied to username, validated during create, and must remain this
        // way to ensure unique moderators within the system.
        validateReadOnly("username", doc.username, oldDoc.username);
      }
    }

    /* Route */
    if (!isDelete()) {
      // Add user to moderator role.
      role(doc.username, "role:moderator");
    } 
    // Add doc to the user's channel.
    var username = doc._deleted ? oldDoc.username : doc.username;
    channel(username);

    /* Grant Read Access */
    if (!isDelete()) {
      // Grant user access to moderators channel.
      access(doc.username, "moderators");
    }
    // Grant user access to their channel.
    access(doc.username, doc.username);
  } else if (getType() == "task-list") { // Task List access control
    /* Write Access */
    var owner = doc._deleted ? oldDoc.owner : doc.owner;
    try {
      // Moderators can create/update lists for other users.
      requireRole("moderator");
    } catch (e) {
      // Users can create/update lists for themselves.
      requireUser(owner);
    }

    /* Validation */
    if (!isDelete()) {
      // Validate required fields.
      validateNotEmpty("name", doc.name);
      validateNotEmpty("owner", doc.owner);

      if (isCreate()) {
        // Validate that the _id is prefixed by owner.
        if (!hasPrefix(doc._id, doc.owner + ".")) {
            throw({forbidden: "task-list id must be prefixed by list owner"});
        }
      } else {
        // Don’t allow task-list ownership to be changed.
        validateReadOnly("owner", doc.owner, oldDoc.owner);
      }
    }

    /* Routing */
    // Add doc to task-list's channel.
    channel("task-list." + doc._id);
    channel("moderators");

    /* Read Access */
    // Grant task-list owner access to the task-list, its tasks, and its users.
    access(owner, "task-list." + doc._id);
    access(owner, "task-list." + doc._id + ".users");
    access("role:moderator", "task-list." + doc._id);
  } else if (getType() == "task") {
    /* Write Access */
    if (!isDelete()) {
      validateNotEmpty("taskList", doc.taskList);
    }
    var owner = doc._deleted ? oldDoc.taskList.owner : doc.taskList.owner;
    var listId = doc._deleted ? oldDoc.taskList.id : doc.taskList.id;
    try {
      requireAccess("task-list." + listId);
    } catch (e) {
      requireUser(owner);
    }

    /* Validate */
    if (!isDelete()) {
      // Validate required fields.
      validateNotEmpty("taskList.id", doc.taskList.id);
      validateNotEmpty("taskList.owner", doc.taskList.owner);
      validateNotEmpty("task", doc.task);

      if (isCreate()) {
        // Validate that the taskList.id is prefixed by taskList.owner.  We only need to
        // validate this during create because these fields are read-only after create.
        if (!hasPrefix(doc.taskList.id, doc.taskList.owner + ".")) {
            throw({forbidden: "task-list id must be prefixed by task-list owner"});
        }
      } else {
        // Don’t allow tasks to be moved to another task-list.
        validateReadOnly("taskList.id", doc.taskList.id, oldDoc.taskList.id);
        validateReadOnly("taskList.owner", doc.taskList.owner, oldDoc.taskList.owner);
      }
    }

    /* Route */
    // Add doc to task-list and moderators channel.
    channel("task-list." + listId);
    channel("moderators");
  } else if (getType() == "task-list.user") {
    /* Control Write Access */
    if (!isDelete()) {
      validateNotEmpty("taskList", doc.taskList);
    }
    var owner = doc._deleted ? oldDoc.taskList.owner : doc.taskList.owner;
    var username = doc._deleted ? oldDoc.username : doc.username;
    try {
      requireUser(owner);
    } catch (e) {
      requireRole("moderator");
    }

    /* Validate */
    if (!isDelete()) {
        // Validate required fields.
        validateNotEmpty("taskList.id", doc.taskList.id);
        validateNotEmpty("taskList.owner", doc.taskList.owner);
        validateNotEmpty("username", doc.username);

        if (isCreate()) {
          // We use a key pattern to ensure unique users w/in a list, so we need to
          // ensure that doc._id matches the pattern {taskList.id}.{username}.
          if (doc._id != doc.taskList.id + "." + doc.username) {
            throw({forbidden: "_id must match the pattern {taskList.id}.{username}."});
          }

          // Validate that the taskList.id is prefixed by taskList.owner.
          if (!hasPrefix(doc.taskList.id, doc.taskList.owner + ".")) {
              throw({forbidden: "task-list id must be prefixed by task-list owner"});
          }
        } else {
          // Don’t allow users to be moved to another task-list.  Also, doc._id is tied to
          // these values, validated during create, and must remain this way to ensure
          // uniqueness within a list.
          validateReadOnly("taskList.id", doc.taskList.id, oldDoc.taskList.id);
          validateReadOnly("taskList.owner", doc.taskList.owner, oldDoc.taskList.owner);
        }
    }

    /* Route */
    // Add doc to task-list users and moderators channel.
    var listId = doc._deleted ? oldDoc.taskList.id : doc.taskList.id;
    channel("task-list." + listId + ".users");
    channel("moderators");

    /* Grant Read Access */
    // Grant the user access to the task-list and its tasks.
    if (!isDelete()) {
      access(doc.username, "task-list." + listId);
    }

    channel(username);
  } else {
    // Log invalid document type error.
    log("Invalid document type: " + doc.type);

    throw({forbidden: "Invalid document type: " + doc.type});
  }

  function getType() {
    return (isDelete() ? oldDoc.type : doc.type);
  }

  function isCreate() {
    // Checking false for the Admin UI to work
    return ((oldDoc == false) || (oldDoc == null || oldDoc._deleted) && !isDelete());
  }

  function isUpdate() {
    return (!isCreate() && !isDelete());
  }

  function isDelete() {
    return (doc._deleted == true);
  }

  function validateNotEmpty(key, value) {
    if (!value) {
      throw({forbidden: key + " is not provided."});
    }
  }

  function validateReadOnly(name, value, oldValue) {
    if (value != oldValue) {
      throw({forbidden: name + " is read-only."});
    }
  }

  // Checks whether the provided value starts with the specified prefix
  function hasPrefix(value, prefix) {
    if (value && prefix) {
      return value.substring(0, prefix.length) == prefix
    } else {
      return false
    }
  }
}
      `
    }
  }
}