Creating Arrays in Hasura

Hasura is one of my favorite tools for building application hosting GraphQL APIs, it is simple to use and suitable for a variety of use cases. However, since using Hasura I have encountered the same problem repeatedly: How to create an array? Since arrays and mappings are not provided in the drop-down menu for row types, what is the best way to do it?

In fact, Hasura can implement the concept of arrays in several different ways, and the following is a breakdown of several methods. My personal favorite is the last method, JSONB, but we'll go through the other methods step by step in case you want to try the others as each has slightly different advantages.

Method 1: Create a literal array manually

Hasura does not provide "array" as type, but we can create a string array by selecting "text" and adding square brackets at the end, as follows:

We will get text[] and will prompt us to create the array in one of two ways:

 <code>["one", "two"] // 或{"one", "two"}</code>

Method 2: Create a relationship

We can also create relationships with another table containing a series of text elements. To do this, create a line with text type.

We will also create a new table via the Add Table button in the sidebar and create a very simple row with unique keys for the type we need (text, integer, or any necessary data).

Now, click on the Relationships tab. In the table, select the Array Relationship option, name it, and refer to the original table you just created.

The ID of the first table should be related to the ID of the second table we just created.

After saving, you should see the reflected array relationship in the table on the same relation tab, with the arrow indicating the direction of the relationship.

 <code>users.gameId → favoriteGames.id</code>

Now we can find the array in the " GraphiQL " tab:

Method 3: JSONB

Here is one of my favorite ways to create arrays in Hasura. I like it because it performs very well. We can use the "JSONB" type and select JSONB from the drop-down menu to create an array. Then we will receive a prompt like the text[] option:

After filling in, it will look like this:

From there, not only can we add arrays to your query like above, we can also search by tag through multiple indexes, and their GraphiQL tabs make exploration easy. See how I filter tags by content containing "animation":

 <code>query MyQuery { codesamples(where: {tags: {_contains: "animation"}}) { userId name id } }</code>

However, such searches are not necessarily efficient when used out of the box, especially when the data volume is large. Fortunately, we can define the fields to index. From the Data tab at the top, select the SQL group in the side panel, where we can define the fields to index to maintain efficient searches. In this example, we will create an index for the "tags" field:

 <code>create index codesample_gin on codesamples using gin(tags)</code>

This will run the query and index this lookup to make it more efficient in the future.

Summarize

Hasura provides an excellent developer experience to set up a fast and easy-to-use GraphQL API. For those interested in setting up arrays using Hasura, I hope this article helps you.

Thanks to Adron Hall of Hasura for proofreading this article.

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