Access control and permissions
Policies in Sails are designed for controlling binary ("yes or no") access to particular actions. They work great for checking whether a user is logged in or for other simple "yes or no" checks, like whether the logged in user is a "super admin".
To see an example of access control in action—as well as login, authentication, and password recovery—generate the starter web app:
sails new foo
# Then choose "Web App"
Dynamic permissions
For more complex permission schemes, like those in which a requesting user agent's access rights depend on both who they are and what they're trying to do, you'll want to involve the database. While you can use policies to accomplish this, it's usually more straightforward and maintainable to use a helper.
For example, you might create api/helpers/check-permissions.js:
module.exports = {
friendlyName: 'Check permissions',
description: 'Look up a user\'s "rights" within a particular organization.',
inputs: {
userId: { type: 'number', required: true },
orgId: { type: 'number', required: true }
},
exits: {
success: {
outputFriendlyName: 'Rights',
outputDescription: `A user's "rights" within an org.`,
outputType: ['string']
},
orgNotFound: {
description: 'No such organization exists.'
}
},
fn: async function(inputs, exits) {
var org = await Organization.findOne(inputs.orgId)
.populate('adminUsers', { id: inputs.userId })
.populate('regularUsers', { id: inputs.userId });
if (!org) { throw 'orgNotFound'; }
var rights = [];
if (org.regularUsers.length !== 0) {
rights = ['basicAccess', 'inviteRegularUsers'];
} else if (org.adminUsers.length !== 0) {
rights = ['basicAccess', 'inviteRegularUsers', 'removeRegularUsers', 'inviteOrgAdmins'];
} else if (org.owner === inputs.userId) {
rights = ['basicAccess', 'inviteRegularUsers', 'removeRegularUsers', 'inviteOrgAdmins', 'removeOrDemoteOrgAdmins'];
}
// ^^This could be as simple or as granular as you need, e.g.
// ['basicAccess', 'inviteRegularUsers', 'inviteOrgAdmins', 'removeRegularUsers', 'removeOrDemoteOrgAdmins']
return exits.success(rights);
}
};
Your action—api/controllers/demote-org-admin.js, for example—might look like this:
//…
var rights = await checkPermissions(this.req.session.userId, inputs.orgId)
.intercept('orgNotFound', 'notFound');
if (!_.contains(rights, 'removeOrDemoteOrgAdmins')) {
throw 'forbidden';
}
await Organization.removeFromCollection(inputs.orgId, 'adminUsers', inputs.targetUserId);
await Organization.addToCollection(inputs.orgId, 'regularUsers', inputs.targetUserId);
return exits.success();
Note
Remember that, while we used
checkPermissions.with(…,…)here, we could have also used.with()and switched to named parameters:await checkPermissions.with({ userId: this.req.session.userId, orgId: inputs.orgId });You may choose to use different ways of calling a helper in order to enhance code readability in different situations. When in doubt, a good best practice is to optimize first for explicitness, then for readability, and last for conciseness. Still, these priorities may shift as you implement a helper more frequently and become more familiar with its usage.
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