如何Work with Shopify’s query Argument in GraphQL

This is a complimentary blog post to a video from theShopifyDevs YouTube channel. In this article, Chuck Kosman, a Launch Engineer at Shopify Plus, rounds up his five part series of tutorials on working with GraphQL. Starting with a simple query, he’ll walk you step-by-step through learning the syntax for creating aqueryargument in GraphQL, and why it might be useful for you. Finally, he’ll point you in the direction of additional resources you can use to keep expanding your knowledge of GraphQL.

Starting a simple query

We're going to cover an argument in particular to Shopify'sAdmin APIthat is called thequeryargument. It allows you to supply a filter on aconnectiontype, so that you can really narrow down your search results without your application having to do that already for you. You can also step back and read up onwhat is GraphQLif you’d like an overview of getting started and the language itself.

I've got a very simple query here:

I have to figure out that I have exactly 21 products in the store, so I named myqueryFirstTwentyOneProductsand I'm using the argument on the products fields for(first:21). All that I'm doing here is gettingedges,node,title, anddescription. We might also gettagstoo because I might want that depending on what other applications are adding and removing tags.

Some of my products fall into a women's category, and some of my products fall into a men's category. In a previous tutorial onGraphQL fragments, I actually added anon-saletag as well to this particular product.

You'll find that this argument,(first:21), can be supplied on anyfieldthat returns aconnectiontype. So, the productsfieldreturns a productsconnection, a list of productedges.

Introducing thequeryargument

I'm going to inspect the syntax of this query in particular. I'm going to click onproducts, and among other parameters that I have, here is one calledquerythat is astring.

It seems like there's a lot of different things I can do with this.

It’s a little bit cut off by my own video, but there are things likebarcode,created at,tag,sku,price,product_type, and so on and so forth. This is a very useful argument in order to allow Shopify to do filtering on your behalf, so that your application does not have to get a whole list of results and then parse through it on its own.

"This is a very useful argument in order to allow Shopify to do filtering on your behalf, so that your application does not have to get a whole list of results and then parse through it on its own."

I'm just going to jump to the productconnection, actually theproductsfield.

OK, so I've jumped here to the definition ofproductson the query route just to see what kinds of things I can do and to show you a really useful link here as well.

Onproductsin particular, just note it'll be different depending on what type ofconnectionyou're getting back. It's saying that you can use these properties of the product for your filter, all these ones here, and the important part here is this link at the bottom that says, “How do you actually use these? What's the syntax that you use to supply this argument?”

So I'm going to go to the “detailed search syntax” link for more.

You might also like:如何Work With Pagination in GraphQL.

Exploring the Shopify API search syntax

There's a whole specification on how to use this particularsearch syntax. There's quite a lot of formal specification. I find the examples to be the most useful if you're just getting started. It kind of looks like this:

To query, you can sayquery=. We're actually going to use=, and then:is actually going to be the same thing.

We can use connectives likeANDorORto chain different ones together.

We can specify whether things should be=or using other comparison operators. We can even say things likeNOT, so this one comes in handy as well.

There’s also a definition of the comparators as well.

Going back to the store, the way I'm going to do this is I’m going to say get me the product whosetitleisOcean Shirt Blue. I don't know the idea ahead of time, I'm just trying to do a look up here.

What I'm going to do is I'm going to supply thequeryargument. Soquery:and then the query itself is astring. We’re going to put in a set of double quotes. Just to confirm, I can indeed query bytitle, so let's do thetitle.

And the way that it’s written is like this:"title: Ocean Shirt Blue". I'll run that query.

Great, so instead of getting me all 21 products in the store, I actually only got back this one because thetitlematched.

Let's do something a little bit more sophisticated or practical.

This is good for atitlelookup. This could also be used for something like aSKUlookup, because it so happens thatSKUis one of the things that I can look for.

Querying a product by itstagin GraphQL

One of the most common use cases of this is finding all products bytag.tag:is the syntax that I need to use, so I'll saytag:. And the schema in my own store for my own tags is that I have a lowercasemenand lowercasewomen.

This returns all products only where thetagon them iswomen.

Another really useful one that some developers and merchants frequently ask about is, "Well, how do we get everything that doesn't have a tag of something?"

For example, if I were to remove this query entirely, just temporarily, and re-issue the simple query, I have one product that's on sale.

如何exclude results with specific tags

Now sometimes, out of interest, people ask, "How do we get all the ones that aren't on sale?"

Well, if we go back to thesearch syntax, we’re going to scroll down to the modifier.

It looks like what we want to do is say-in front of thefieldthat we want to eliminate, and use the:as the comparison operator to say equal to and then thetagitself.

What we’re going to say is:query:“-tag:on-sale”.

Now if I were to scroll through, I’d get everything that doesn't include thetagon-sale.

我可以同样well combine this. Let's say I didn't wanttagon-sale,我只希望男人的物品that are noton-sale. I could say something like,query:“-tag:on-sale AND tag: men”.

That will give me all of the products tagged withmenbut not tagged withquery. You can combine a lot of different ones like this to make really sophisticated filters that Shopify is providing you, so that your application doesn't have to do it on your behalf.

Additional resources to expand your knowledge of GraphQL

We’ll finish with some additional learning resources that are well worth looking at to further explore some of the topics that we’ve discussed over the course of our GraphQL series.

"First and foremost,graphql.orgis an excellent place to learn all things GraphQL."

首先,也是最重要的,graphql.orgis an excellent place to learn all things GraphQL. There are two different parts of the site that are particularly very useful for covering some of the content that was covered here in our tutorials:

1. The“learn”resource has a lot of the concise descriptions of the different features we’ve covered, things like aliases, fragments, working with pagination, and so on
2. The“code”section of the website has a listing of different server and client libraries that you can start working with if you want to move beyond GraphQL

This resource is actually where I was first introduced to the graphql-request library that I demoed in my code editor in an earlier part of this tutorial, when we looked at how to useGraphQL operation names and variables.

You might also like:如何Build a Shopify App in One Week.

If you're interested in learning more about cursor-based pagination and where the specification came from, I recommend a source from a library calledRelay. This set forth the specification that many GraphQL schemas now use.

If you want to see the difference between cursor and offset pagination, I highly recommendthis blog postfrom hasura.io.

You can also visit theAdvanced Concepts GraphQL sectionin the Shopify docs, Shopify’s concise guide to some of these topics. That covers using aliases to use the same fields more than once, and fragments to actually retrieve the data.

Finally, if you ever need a reference for thatqueryargument, you can use theShopify API search syntax.