如何将额外的参数传递给RxJS映射运算符 [英] How to pass extra parameters to RxJS map operator

问题描述

在Angular应用中，我使用 HttpClient 和RxJS运算符进行一些API调用.例如:

In an Angular app, I use HttpClient and RxJS operators to make some API calls. For example:

return this.httpClient.put(url, JSON.stringify(treeOptions))
        .pipe(
        map(this.extractTreeData),
        catchError(this.handleError)
        );

extractTreeData 方法基本上更改了API返回的一些属性:

The extractTreeData method basically changes some properties returned by the API:

private extractTreeData(res: any) {
    let apiTree = res.data;  // The tree comes inside the 'data' field
    let newTree : any;

    try {
        let str = JSON.stringify(apiTree);

        str = str.replace(/"children"/g, '"items"');
        str = str.replace(/"allowdrag"/g, '"allowDrag"');

        newTree = JSON.parse(str);        
    } catch(e) {
        // Error while parsing
        newTree = null;
    }

    return newTree || {};
}

我需要根据树的类型进行更多更改.如何将这种类型传递给映射方法?我的意思是:

I need to do some more changes depending on the type of tree. How could I pass this type to the mapped method? I mean:

[...]
.pipe(
  map(this.extractTreeData), <== HOW TO PASS VARIABLE 'treeType' TO extractTreeData
[...]

预先感谢

推荐答案

行

map(this.extractTreeData)

等同于

map(tree => this.extractTreeData(tree))

如果使用扩展形式，则可以对其进行更新以传递更多参数，如下所示:

If you use the expanded form, you can then update it to pass more parameters as follows:

map(tree => this.extractTreeData(tree，treeType))

尽管您没有显示 treeType 的来源，但是很难给您完整的答案.

It is hard to give you a full answer though as you don't show where treeType is coming from.

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