Prisma graphql计算字段 [英] Prisma graphql computed fields
问题描述
我有这个数据模型:
type Item {
id: ID! @unique
title: String!
description: String!
user: User!
pictures: [Picture]
basePrice: Int!
addons: [Addon]
}
我正在编写一个名为parsedItem的查询,该查询从参数中获取ID并查找Item(使用Prisma生成的Item的默认查询),如下所示:
I'm writing a query called parsedItem that takes the id from arguments and looks for the Item (using the default query for Item generated by Prisma), something like this:
const where = { id: args.id };
const item = await ctx.db.query.item({ where },
`{
id
title
...
我需要在前端显示一个计算值:"dynamicPrice",它取决于Item拥有的附加组件的数量.例如:项目#1有3个插件,每个插件的价值为$ 5.计算得出的值应该是
I need to show on the frontend a computed value: "dynamicPrice" it depends on the quantity of the Addons that the Item has. e.g: Item #1 has 3 addons, each addons has a value of $5. This calculated value should be
dynamicPrice = basePrice + 3 * 5
Addon关系可能会改变,因此我需要在前端发出的每个请求中都对此进行计算.
The Addon relation could change, so I need to compute this in every request the frontend makes.
我非常想做类似的事情:
I'd like so much to do something like:
item.dynamicPrice = item.basePrice + (item.addons.length * 5)
并在解析器中返回此项目,但这不起作用.那抛出一个错误:
and return this item in the resolver, but this doesn't work. That throw an error:
"message":无法查询类型\" Item \的字段\" dynamicPrice \.(当我尝试从前端查询商品时)
此错误消息使我想到:是否应该将dynamicPrice创建为数据模型上的字段?然后可以在查询解析器中填充此字段吗?我知道我可以,但这是一个好方法吗?
This error message makes me think: Should I create dynamicPrice as a field on the datamodel? Can I then populate this field in the query resolver? I know I can, but is this a good approach?
这是一个示例,我需要为此Item模型创建更多计算值.
This is an example, I need to create more computed values for this Item model.
对于这种简单的用例,最佳的可扩展解决方案/解决方案是什么?
推荐答案
您需要为 Item
类型的 dynamicPrice
字段创建字段解析器.看起来像这样:
You need create field resolver for dynamicPrice
field at Item
type. It will looks like that:
const resolvers = {
Query: {
parsedItem: (parent, args, ctx, info) => {
...
}
...
},
Item: {
dynamicPrice: parent => parent.basePrice + parent.addons.length * 5
}
}
您可以在指南中找到更多详细信息常见的解析器模式.
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