使用XfMaps读取XML：扁平化示例-从XML文件中提取所有属性

ArticlebyMitaAtSafe·2016年2月11日晚上09:34·edited·2018年5月14日下午06:37

Article created with FME Desktop 2016.0

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Here is a technique for recursively extracting all attributes from below a tag match. This little trick can allow any FME user to read almost any XML dataset quickly, so it is very powerful. It can also be combined with XML geometry reading methods.

Description

许多用户在阅读复杂的xml或gml时遇到问题。方法是使用FME的通用XML读取器。这可以通过特征路径完成。然而，xfmaps是xml解释脚本，它使您能够完全灵活地以您想要的方式读取xml，包括几何图形解释，这是featurepath尚不支持的。基本思想是在featuremapping部分中指定xml结构中要生成要素类型的节点。然后在“要素内容映射”区域中指定这些要素中的每一个要素所包含的内容。

XfMap Structure Command

This can take a fair bit of time to list out all your attributes, so here is a technique for recursively extracting all attributes from below a tag match. This little trick can allow any FME user to read almost any xml dataset, so it is very powerful.

The 'mapping match="Feature/*"' means that this maps all children whose parent is . The command flattens their names from:

约翰温哥华11-22-9912-11-09

to:

attribute1=John attribute2=wincover activeDate\u from=11-22-99 activeDate\u to=12-11-09

Considerations

The only caveat is that it builds attribute names of the form parent_childAttrbite for everything below the tag matched. Also, where 'childAttribute' occurs multiple times, you get a list construct in FME childAttribute{0}, childAttribute{1}. You could then decide to match the tag at the childAttribute level rather than the parent level, or you could use a ListExploder within FME to create individual features for every list element.

The point is, this is a quick way to read xml data into FME, particularly if it is attribute only. You can mix literal definitions with these recursive definitions, so long as they dont overlap. If you try to match a tag twice the first one the interpreter hits wins, so to avoid conflict, you need to list the tags you dont want recursively deconstructed under the exceptions.

Source XML example

Suppose we want to read the source xml below. The structure command above would allow us to read all the attributes below the tag. But how would we read the geometry as well?

John温哥华11-22-9912-11-09-123.1,49.25-122.9，49.15六月萨里02-25-059-15-10-122.8,49.12-122.5,49.0

Adding Geometry to Structure XFMaps

The trick is to define an exception so that we dont try to render the geometry field 'Coordinate_BOX' automatically into an attribute. We do this by qualifying the mapping expression with:

 
这意味着structure命令将遍历Feature/*（因此是通配符）下面的所有元素，但跳过Coordinate\u BOX元素。然后我们可以像在基本示例中那样处理长方体几何体：      
                  
                   
总而言之，我们现在有了一个xfmap，它将为创建一个新的feature类型，动态地捕获下的所有元素作为属性，并向其中添加长方体几何体。我知道，这个xfmap的东西可能看起来有点奇怪，但是一旦你玩了一些这样的例子，你就会发现它并不像你现在想象的那么可怕。已完成“展平示例”XFmap

xml xfmaps

source.xml (641 B)

xfmap-structure.xml (1.2 kB)

xml2ffs格式-结构.fmw (24.3 kB)

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10 |4000characters needed剩余字符数超过个字符

附件：最多可以使用10个附件（包括图像），每个附件最多4.0 MB，总共4.0 MB。

使用XfMaps读取XML：扁平化示例-从XML文件中提取所有属性

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Description

XfMap Structure Command

Considerations

Source XML example

Adding Geometry to Structure XFMaps

已完成“展平示例”XFmap

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