Collection

Collection is a way to group and sort data. For example in a blog, you can use collection to sort all your blog posts by dateCreated in descending order. You may also want another collection with blog posts grouped by tags.

Collection config

Add collections in your sambal.site.js file with the following schema

export const siteConfig = {
    // ... other configs
    collections: [
        {
            uri: "/blogs/byAuthor",                                          // REQUIRED - collection uri
            include: ["blogs/**/*"],                                         // REQUIRED - Globs to match uris
            groupBy: (mainEntity) => {                                       // OPTIONAL - Group by partition key
                return {
                    // group by author's name
                    author: mainEntity.author.name
                };
            },
            sort: (a, b) => {                                                // OPTIONAL - Sort
                return b.dateCreated.getTime() - a.dateCreated.getTime();
            }
        }
    ]
};

Different ways to group by

Group by function returns one or more arbitrary partition key in which all content with the same partition key will be grouped.

(mainEntity) => {
    // group by year
    return {
        year: mainEntity.dateCreated.getFullYear()
    }
}

(mainEntity) => {
    // group by section and author
    return {
        section: mainEntity.articleSection,
        author: mainEntity.author.name
    }
}

(mainEntity) => {
    // group by each tag
    return mainEntity.keywords.map(tag => ({
        tag: tag
    }));
}

Using collection

Say you want to render a list of blogposts ordered by date created, you can define a collection of all your blogposts sorted by date

export const siteConfig = {
    // ... other configs
    collections: [
        {
            uri: "/blogs/latest",
            include: ["blogs/**/*"],
            sort: (a, b) => {
                return b.dateCreated.getTime() - a.dateCreated.getTime();
            }
        }
    ]
};

You can then access the collection by it's uri in your /blogs yaml file

"@type": "ItemList"
itemListElement:
  "@id": /blogs/latest

Sambal will output a collection as a schema.org ItemList

{
    "@type": "ItemList",
    itemListElement: [
        {
            "@type": "BlogPosting",
            ...more blog props
        },
        ...more blogposting
    ]
}

Querying collection by partition key

If your collection implemented a groupBy function, you can query your collection by the partition key. For example, the /blogs/byAuthor collection above is partitioned by author's name so to get a list of all blogposts by John Smith, you can query with this uri

/blogs/byAuthor?author=John Smith

Or if you are partitioning by author and year like so

(mainEntity) => {
    // group by section and author
    return {
        author: mainEntity.author.name,
        year: mainEntity.dateCreated.getFullYear()
    }
}

You can get a list of all blogposts by John Smith written in 2019 with this uri

/blogs/byAuthor?author=John Smith&year=2019