CODEWITHSUNDEEP
gographql
majidarif
majidarif

Reputation: 20005

Passing variables with graphql using a http client

I'm trying to interface with shopify storefront api in golang. But this is my first encounter with graphql and I'm a bit confused.

I need to pass variables for the request and did some research where I came to the conclusion that I could pass variables like shown below. But shopify keeps returning this error:

{"errors":[{"message":"Parse error on \"variables\" (IDENTIFIER) at [13, 3]","locations":[{"line":13,"column":3}]}]}

Here is my current code:

body := strings.NewReader(fmt.Sprintf(`
    mutation ($checkoutId: ID!, $lineItems: [CheckoutLineItemInput!]!) {
        checkoutLineItemsAdd(checkoutId: $checkoutId, lineItems: $lineItems) {
          userErrors {
            message
            field
          }
          checkout {
            id
          }
        }
      }
    variables: { "lineItems": [ { "quantity": 1, "variantId": "%s" } ], "checkoutId": "%s" }
`, productID, checkoutID))

req, err := http.NewRequest("POST", "https://myshop.myshopify.com/api/graphql", body)
if err != nil {
    // handle err
    fmt.Println(err)
}
req.Header.Set("Content-Type", "application/graphql")
req.Header.Set("X-Shopify-Storefront-Access-Token", "mytoken")

resp, err := http.DefaultClient.Do(req)
if err != nil {
    // handle err
    fmt.Println(err)
}
defer resp.Body.Close()

data, err := ioutil.ReadAll(resp.Body)
if err != nil {
    // handle err
    fmt.Println(err)
}

My question is, what is the correct way of passing variables when using application/graphql?

After updating the code with the answer of @DanielRearden I'm now getting this error:

{"errors":[{"message":"Variable checkoutId of type ID! was provided invalid value","locations":[{"line":1,"column":11}],"extensions":{"value":null,"problems":[{"path":[],"explanation":"Expected value to not be null"}]}},{"message":"Variable lineItems of type [CheckoutLineItemInput!]! was provided invalid value","locations":[{"line":1,"column":29}],"extensions":{"value":null,"problems":[{"path":[],"explanation":"Expected value to not be null"}]}}]}

Updated code:

    body := strings.NewReader(fmt.Sprintf(`{
        "query": "mutation ($checkoutId: ID!, $lineItems: [CheckoutLineItemInput!]!) { checkoutLineItemsAdd(checkoutId: $checkoutId, lineItems: $lineItems) { userErrors { message field } checkout { id } }}",
        "variables": { 
            "$lineItems": [ 
                { "quantity": 1, "variantId": "%s" }
            ], 
            "$checkoutId": "%s"
        }
    }`, productID, checkoutID))
    ...
    ...
    req.Header.Set("Content-Type", "application/json")

Removing the $ token on the variables as shown below returns another error:

{
        "query": "mutation ($checkoutId: ID!, $lineItems: [CheckoutLineItemInput!]!) { checkoutLineItemsAdd(checkoutId: $checkoutId, lineItems: $lineItems) { userErrors { message field } checkout { id } }}",
        "variables": { 
            "checkoutId": "%s",
            "lineItems": [ 
                { "quantity": 1, "variantId": "%s" }
            ]
        }
    }

And the error is: (status 500)

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8" />
  <meta name="referrer" content="never" />
  <title>Something went wrong</title>

But I guess this is not a graphql issue anymore but more of a shopify api problem.

Upvotes: 4

Views: 4173

Answers (1)

Daniel Rearden
Daniel Rearden

Reputation: 84687

You can't use variables when you set the Content Type to application/graphql because the entire request body is treated as a single GraphQL document. Variables cannot be included inside a GraphQL document -- they have to be submitted separately. Instead of using application/graphql, you should use application/json as the Content Type. Then, your request body should be a JSON string with two keys -- query and variables:

{
  "query": "mutation ($checkoutId: ID!, $lineItems: [CheckoutLineItemInput!]!) {...}",
  "variables": {
    "checkoutId" "",
    "lineItems": [
      ...
    ]
  }
}

Upvotes: 12

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