Relay/GraphQL 将自定义字段添加到连接答案

【问题标题】：Relay/GraphQL add custom field to connectionRelay/GraphQL 将自定义字段添加到连接
【发布时间】：2016-11-13 10:53:37
【问题描述】：

我正在尝试添加要用于分页的记录总数。现在我可以看到我无法修改它以使我的 totalCount 与它分开的连接。

    Books: {
        type: BooksConnection.connectionType,
        args: { ...connectionArgs, isbn: { type: GraphQLString }, publisher: {type: GraphQLString}},
        resolve: ( obj, { ...args }, context, { rootValue: objectManager } ) =>
        {
            let user = obj;
            let FormatedArgs = MasterFields.FormatPredicate(args);
            return objectManager.getListBy( 'Book', user, FormatedArgs.queryArgs, objectManager.getViewerUserId( ) ).then( ( arr ) =>
            {

                let result = {};
                result.Books = arr;
                result.totalCount = arr.length;
;
                //Originally i would just pass arr instead of result.
                return connectionFromArray( result, FormatedArgs.connArgs);
            } )
        }
    },

在这种情况下，当我在 BookConnection 中获取连接对象时。我希望能够将该值分配给一个字段。

export default connectionDefinitions( {
    name: 'Books',
    nodeType: BookType,
    connectionFields: () => ({
        totalCount: {
            type: GraphQLInt,
            resolve: (connection) => { console.log(connection); return connection.totalCount; },
            description: `A count of the total number of objects in this connection, ignoring pagination.
This allows a client to fetch the first five objects by passing "5" as the
argument to "first", then fetch the total count so it could display "5 of 83",
for example.`
        }
})
});

如何使totalCount 成为connection 变量的属性？

我在这里找到了部分答案：How to pass total count to the client in pageInfo

【问题讨论】：

标签： graphql relayjs relay

【解决方案1】：

这点在看了一个小时左右后就很明显了。我不知道如何从connectionFromArray() 接收totalCount 值这就是我覆盖它的方式。

    Books: {
        type: BooksConnection.connectionType,
        args: { ...connectionArgs, isbn: { type: GraphQLString }, publisher: {type: GraphQLString}},
        resolve: ( obj, { ...args }, context, { rootValue: objectManager } ) =>
        {
            let user = obj;
            let FormatedArgs = MasterFields.FormatPredicate(args);
            return objectManager.getListBy( 'Book', user, FormatedArgs.queryArgs, objectManager.getViewerUserId( ) ).then( ( arr ) =>
            {

                let result  = connectionFromArray( arr, FormatedArgs.connArgs);
;
                result.pageInfo.totalCount = arr.length;


                return result;
            } )
        }
    },

现在这是我在抱怨。

function connectionFromArray(data, args) {
  return connectionFromArraySlice(data, args, {
    sliceStart: 0,
    arrayLength: data.length
  });
}
function connectionFromArraySlice(arraySlice, args, meta) {
  var after = args.after;
  var before = args.before;
  var first = args.first;
  var last = args.last;
  var sliceStart = meta.sliceStart;
  var arrayLength = meta.arrayLength;

  var sliceEnd = sliceStart + arraySlice.length;
  var beforeOffset = getOffsetWithDefault(before, arrayLength);
  var afterOffset = getOffsetWithDefault(after, -1);

  var startOffset = Math.max(sliceStart - 1, afterOffset, -1) + 1;
  var endOffset = Math.min(sliceEnd, beforeOffset, arrayLength);
  if (typeof first === 'number') {
    endOffset = Math.min(endOffset, startOffset + first);
  }
  if (typeof last === 'number') {
    startOffset = Math.max(startOffset, endOffset - last);
  }

  // If supplied slice is too large, trim it down before mapping over it.
  var slice = arraySlice.slice(Math.max(startOffset - sliceStart, 0), arraySlice.length - (sliceEnd - endOffset));

  var edges = slice.map(function (value, index) {
    return {
      cursor: offsetToCursor(startOffset + index),
      node: value
    };
  });

上面是具有此功能的graphql-relay lib。当他们显然有它在那里执行分页时，不传递给我们arrayLength的目的是什么？

【讨论】：