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f# - 如何遍历 Odata 实体模型图？

问题描述

#r "nuget: Microsoft.OData.Edm"

open Microsoft.OData.Edm
open System.Xml

let reader = XmlReader.Create("metadata.xml")
let success, edmModel, errors  = Csdl.CsdlReader.TryParse(reader)

let container = edmModel.EntityContainer
let elements = edmModel.SchemaElements |> Seq.cast<IEdmSchemaElement> |> Array.ofSeq

for elem in elements do
    printfn $"1  {elem.Name} : {elem.SchemaElementKind} : {elem.Location()}"

let entitySets = container.EntitySets() |> Seq.cast<IEdmEntitySet> |> Array.ofSeq

for elem in entitySets do
    let cElems = elem.Container.Elements |> Seq.cast<IEdmEntityContainerElement> |> Array.ofSeq
    printfn $"   2  {elem.Name} : {elem.ContainerElementKind}"

    for celem in cElems do
        printfn $"      3  {celem.Name} : {celem.ContainerElementKind}"

这是我可以使用 Microsoft.OData.Edm 遍历 odata 实体模型图的程度。2 级和 3 级打印的结果是相同的。我想访问实体类型的键和属性。

我总是可以切换到走 XML 图，但使用维护的 odata 库似乎是正确的做法。

标签： f#odata

解决方案

我认为这里的诀窍是尽可能将元素向下转换IEdmEntityType：

let entTypes =
    edmModel.SchemaElements
        |> Seq.choose (function
            | :? IEdmEntityType as entType -> Some entType
            | _ -> None)
for entType in entTypes do
    printfn "%s" entType.Name
    for prop in entType.DeclaredProperties do
        printfn "   %s %s" prop.Name (prop.Type.ShortQualifiedName())

输出将类似于：

Product
   ID Int32
   Name String
   Description String
   ReleaseDate DateTimeOffset
   DiscontinuedDate DateTimeOffset
   Rating Int16
   Price Double
   Categories
   Supplier ODataDemo.Supplier
   ProductDetail ODataDemo.ProductDetail
FeaturedProduct
   Advertisement ODataDemo.Advertisement
ProductDetail
   ProductID Int32
   Details String
   Product ODataDemo.Product

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