爬虫请求返回「必须提供查询字符串」错误的原因排查

目标页面 #

https://www.sayurbox.com/category/vegetables-1-a0d03d59?selectedCategoryType=ops&touch_point=screen_CATEGORY_sembako-1-e6a33b51&section_source=shop_list_slider_navigation_category_vegetables-1-a0d03d59

原代码 #

dcID="RGVsaXZlcnlDb25maWc6VGh1cnNkYXksIDA5IEZlYnJ1YXJ5IDIwMjN8SkswMXxTRDI5fGZhbHNl"
slugcat="vegetables-1-a0d03d59"
url="https://www.sayurbox.com/graphql/v1?deduplicate=1"

payload={"operationName":"getCartItemCount",
           "variables":{"deliveryConfigId":DCId},
           "query":"query getCartItemCount($deliveryConfigId: ID!) {
  cart(deliveryConfigId: $deliveryConfigId) {
    id
    count
    __typename
  }
}"},{"operationName":"getProducts",
            "variables":{"deliveryConfigId":DCId,
                         "sortBy":"related_product",
                         "isInstantDelivery":False,
                         "slug":slugcat,
                         "first":12,
                         "abTestFeatures":[]},
            "query":"query getProducts($deliveryConfigId: ID!, $sortBy: CatalogueSortType!, $slug: String!, $after: String, $first: Int, $isInstantDelivery: Boolean, $abTestFeatures: [String!]) {
  productsByCategoryOrSubcategoryAndDeliveryConfig(
    deliveryConfigId: $deliveryConfigId
    sortBy: $sortBy
    slug: $slug
    after: $after
    first: $first
    isInstantDelivery: $isInstantDelivery
    abTestFeatures: $abTestFeatures
  ) {
    edges {
      node {
        ...ProductInfoFragment
        __typename
      }
      __typename
    }
    pageInfo {
      hasNextPage
      endCursor
      __typename
    }
    productBuilder
    __typename
  }
}

fragment ProductInfoFragment on Product {
  id
  uuid
  deliveryConfigId
  displayName
  priceRanges
  priceMin
  priceMax
  actualPriceMin
  actualPriceMax
  slug
  label
  isInstant
  isInstantOnly
  nextDayAvailability
  heroImage
  promo
  discount
  isDiscount
  variantType
  imageIds
  isStockAvailable
  defaultVariantSkuCode
  quantitySoldFormatted
  promotion {
    quota
    isShown
    campaignId
    __typename
  }
  productVariants {
    productVariant {
      id
      skuCode
      variantName
      maxQty
      isDiscount
      stockAvailable
      promotion {
        quota
        campaignId
        isShown
        __typename
      }
      __typename
    }
    pageInfo {
      hasPreviousPage
      hasNextPage
      __typename
    }
    __typename
  }
  __typename
}"}

response=requests.get(url,headers=headers,json=payload)
response.json()

错误返回结果 #

[{'errors': [{'message': 'Must provide query string.',
    'extensions': {'timestamp': 1675842901472}}]},
 {'errors': [{'message': 'Must provide query string.',
    'extensions': {'timestamp': 1675842901472}}]}]

问题排查与修复 #

1. 请求方法错误 #

GraphQL接口几乎都使用POST请求接收JSON格式的请求体，你用了requests.get()，GET请求不会将json参数放入请求体，服务端无法获取到query内容，直接返回"Must provide query string."错误。

2. 变量名大小写不匹配 #

代码中定义的变量是dcID，但payload里写的是DCId，Python是大小写敏感的，这会导致传递的deliveryConfigId值错误（甚至可能抛出未定义错误）。

3. 批量请求格式（可选） #

如果要发送批量GraphQL请求，需要将payload包装为一个列表，但要确认目标服务端支持批量请求；如果不需要同时获取购物车数量和商品列表，可以拆分请求单独发送。

修正后的代码示例 #

import requests

dcID = "RGVsaXZlcnlDb25maWc6VGh1cnNkYXksIDA5IEZlYnJ1YXJ5IDIwMjN8SkswMXxTRDI5fGZhbHNl"
slugcat = "vegetables-1-a0d03d59"
url = "https://www.sayurbox.com/graphql/v1?deduplicate=1"

# 商品列表请求payload
products_payload = {
    "operationName": "getProducts",
    "variables": {
        "deliveryConfigId": dcID,
        "sortBy": "related_product",
        "isInstantDelivery": False,
        "slug": slugcat,
        "first": 12,
        "abTestFeatures": []
    },
    "query": """query getProducts($deliveryConfigId: ID!, $sortBy: CatalogueSortType!, $slug: String!, $after: String, $first: Int, $isInstantDelivery: Boolean, $abTestFeatures: [String!]) {
  productsByCategoryOrSubcategoryAndDeliveryConfig(
    deliveryConfigId: $deliveryConfigId
    sortBy: $sortBy
    slug: $slug
    after: $after
    first: $first
    isInstantDelivery: $isInstantDelivery
    abTestFeatures: $abTestFeatures
  ) {
    edges {
      node {
        ...ProductInfoFragment
        __typename
      }
      __typename
    }
    pageInfo {
      hasNextPage
      endCursor
      __typename
    }
    productBuilder
    __typename
  }
}

fragment ProductInfoFragment on Product {
  id
  uuid
  deliveryConfigId
  displayName
  priceRanges
  priceMin
  priceMax
  actualPriceMin
  actualPriceMax
  slug
  label
  isInstant
  isInstantOnly
  nextDayAvailability
  heroImage
  promo
  discount
  isDiscount
  variantType
  imageIds
  isStockAvailable
  defaultVariantSkuCode
  quantitySoldFormatted
  promotion {
    quota
    isShown
    campaignId
    __typename
  }
  productVariants {
    productVariant {
      id
      skuCode
      variantName
      maxQty
      isDiscount
      stockAvailable
      promotion {
        quota
        campaignId
        isShown
        __typename
      }
      __typename
    }
    pageInfo {
      hasPreviousPage
      hasNextPage
      __typename
    }
    __typename
  }
  __typename
}"""
}

# 使用POST请求，传入headers（确保headers包含正确的Content-Type等信息）
response = requests.post(url, headers=headers, json=products_payload)
print(response.json())

内容的提问来源于stack exchange，提问作者Hal