Schema Management Examples

FDO API

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Creating and Editing a GML Schema File

Schema Management

Data Maintenance

Schema Management Examples

Example: Creating a Feature Schema

The following sample code creates an FdoFeatureSchema object called “SampleFeatureSchema.” The schema contains one class, which has three properties. The class and its properties conform to the table definition for the Lakes feature in the Open GIS Consortium document 98-046r1. This table definition is expressed in an XML format on page 10 of the document and is reproduced as follows:

<ogc-sfsql-table>

  <table-definition>

    <name>lakes</name>

    <column-definition>

      <name>fid</name>

      <type>INTEGER</type>

      <constgraint>NOT NULL</constraint>

      <constraint>PRIMARY KEY<constraint>

    </column-definition>

    <column-definition>

      <name>name</name>

      <type>VARCHAR(64)</type>

    </column-definition>

    <column-definition>

      <name>shore</name>

      <type>POLYGON</type>

    </column-definition>

  </table-definition>

The table definition whose name is “lakes” is mapped to an FdoFeatureClass object called “SampleFeatureClass.” The column definition whose name is “fid” is mapped to an FdoDataPropertyDefinition object called “SampleIdentityDataProperty.” The column definition whose name is “name” is mapped to an FdoDataPropertyDefinition object called “SampleNameDataProperty.” The column definition whose name is “shore” is mapped to an FdoGeometricPropertyDefinition object called “SampleGeometricProperty.”

// Create the ApplySchema command

FdoPtr<FdoIApplySchema> sampleApplySchema;

sampleApplySchema = (FdoIApplySchema *)

  connection->CreateCommand(FdoCommandType_ApplySchema);

// Create the feature schema

FdoPtr<FdoFeatureSchema> sampleFeatureSchema;

sampleFeatureSchema = FdoFeatureSchema::Create(L"SampleFeatureSchema", L"Sample Feature Schema Description");

// get a pointer to the feature schema's class collection

// this object is used to add classes to the schema

FdoPtr<FdoClassCollection> sampleClassCollection;

sampleClassCollection = sampleFeatureSchema->GetClasses();

// create a feature class, i.e., a class containing a geometric

// property set some class level properties

FdoPtr<FdoFeatureClass> sampleFeatureClass;

sampleFeatureClass = FdoFeatureClass::Create(L"SampleFeatureClass", L"Sample Feature Class Description");

sampleFeatureClass->SetIsAbstract(false);

// get a pointer to the feature class's property collection

// this pointer is used to add data and other properties to the class

FdoPtr<FdoPropertyDefinitionCollection> sampleFeatureClassProperties;

sampleFeatureClassProperties = sampleFeatureClass->GetProperties();

// get a pointer to the feature schema's class collection

// this object is used to add classes to the schema

FdoPtr<FdoClassCollection> sampleClassCollection;

sampleClassCollection = sampleFeatureSchema->GetClasses();

// get a pointer to the feature class's identity property collection

// this property is used to add identity properties to the feature

// class

FdoPtr<FdoDataPropertyDefinitionCollection> sampleFeatureClassIdentityProperties;

sampleFeatureClassIdentityProperties = sampleFeatureClass->GetIdentityProperties();

// create a data property that is of type Int32 and identifies

// the feature uniquely

FdoPtr<FdoDataPropertyDefinition> sampleIdentityDataProperty;

sampleIdentityDataProperty = FdoDataPropertyDefinition::Create(L"SampleIdentityDataProperty", L"Sample Identity Data Property Description");

sampleIdentityDataProperty->SetDataType(FdoDataType_Int32);

sampleIdentityDataProperty->SetReadOnly(false);

sampleIdentityDataProperty->SetNullable(false);

sampleIdentityDataProperty->SetIsAutoGenerated(false);

// add the identity property to the sampleFeatureClass

sampleFeatureClassProperties->Add(sampleIdentityDataProperty);

sampleFeatureClassIdentityProperties->Add(sampleIdentityDataProperty);

// create a data property that is of type String and names the

// feature

FdoPtr<FdoDataPropertyDefinition> sampleNameDataProperty;

sampleNameDataProperty = FdoDataPropertyDefinition::Create(L"SampleNameDataProperty", L"Sample Name Data Property Description");

sampleNameDataProperty->SetDataType(FdoDataType_String);

sampleNameDataProperty->SetLength(64);

sampleNameDataProperty->SetReadOnly(false);

sampleNameDataProperty->SetNullable(false);

sampleNameDataProperty->SetIsAutoGenerated(false);

// add the name property to the sampleFeatureClass

sampleFeatureClassProperties->Add(sampleNameDataProperty);

// create a geometric property

FdoPtr<FdoGeometricPropertyDefinition> sampleGeometricProperty;

sampleGeometricProperty = FdoGeometricPropertyDefinition::Create(L"SampleGeometricProperty", L"Sample Geometric Property Description");

sampleGeometricProperty->SetGeometryTypes(FdoGeometricType_Surface);

sampleGeometricProperty->SetReadOnly(false);

sampleGeometricProperty->SetHasMeasure(false);

sampleGeometricProperty->SetHasElevation(false);

// add the geometric property to the sampleFeatureClass

sampleFeatureClassProperties->Add(sampleGeometricProperty);

// identify it as a geometry property

sampleFeatureClass->SetGeometryProperty(sampleGeometricProperty);

// add the feature class to the schema

sampleClassCollection->Add(sampleFeatureClass);

// point the ApplySchema command at the newly created feature

// schema and execute

sampleApplySchema->SetFeatureSchema(sampleFeatureSchema);

sampleApplySchema->Execute();

Example: Describing a Schema and Writing It to an XML File

The following sample code demonstrates describing a schema and writing it to an XML file:

// create the DescribeSchema command

FdoPtr<FdoIDescribeSchema> sampleDescribeSchema;

sampleDescribeSchema = (FdoIDescribeSchema *)

  connection->CreateCommand(FdoCommandType_DescribeSchema);

// executing the DescribeSchema command returns a feature

// schema collection that is, the set of feature schema which

// reside in the DataStore

FdoPtr<FdoFeatureSchemaCollection> sampleFeatureSchemaCollection;

sampleFeatureSchemaCollection = sampleDescribeSchema->Execute();

// find the target feature schema in the collection, write it

// to an xml file, and clear the collection

sampleFeatureSchema = sampleFeatureSchemaCollection->FindItem(L"SampleFeatureSchema");

sampleFeatureSchema->WriteXml(L"SampleFeatureSchema.xml");

sampleFeatureSchemaCollection->Clear();

Example: Destroying a Schema

The following sample code demonstrates destroying a schema:

// create the DestroySchema command

FdoPtr<FdoIDestroySchema> sampleDestroySchema;

sampleDestroySchema = (FdoIDestroySchema *)

  connection->CreateCommand(FdoCommandType_DestroySchema);

// destroy the schema

sampleDestroySchema->SetSchemaName(L"SampleFeatureSchema");

sampleDestroySchema->Execute();

Example: Creating a Schema Read In from an XML File

The following sample code demonstrates creating a schema read in from an XML file:

sampleFeatureSchemaCollection->ReadXml(L"SampleFeatureSchema.xml");

sampleFeatureSchema = sampleFeatureSchemaCollection->FindItem(L"SampleFeatureSchema");

sampleApplySchema->SetFeatureSchema(sampleFeatureSchema);

sampleApplySchema->Execute();

sampleFeatureSchemaCollection->Clear();

SampleFeatureSchema.xml

The following sample XML schema is the contents of the file written out by the WriteXml method belonging to the FdoFeatureSchema class object that was created in the preceding sample code:

<?xml version="1.0" encoding="UTF-8" ?>

  <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"

    targetNamespace="http://fdo_customer/SampleFeatureSchema"

    xmlns:fdo="http://fdo.osgeo.org/schema"

    xmlns:gml="http://www.opengis.net/gml"

    xmlns:SampleFeatureSchema="http://fdo_customer/

      SampleFeatureSchema"

    elementFormDefault="qualified"

    attributeFormDefault="unqualified">

  <xs:annotation>

    <xs:documentation>Sample Feature Schema Description

      </xs:documentation>

    <xs:appinfo source="http://fdo.osgeo.org/schema" />

  </xs:annotation>

  <xs:element name="SampleFeatureClass"

    type="SampleFeatureSchema:SampleFeatureClassType"

    abstract="false" substitutionGroup="gml:_Feature">

    <xs:key name="SampleFeatureClassKey">

      <xs:selector xpath=".//SampleFeatureClass" />

      <xs:field xpath="SampleIdentityDataProperty" />

    </xs:key>

  </xs:element>

  <xs:complexType name="SampleFeatureClassType"

    abstract="false"

    fdo:geometryName="SampleGeometricProperty"

    fdo:hasMeasure="false"

    fdo:hasElevation="false"

    fdo:srsName="SC_0"

    fdo:geometricTypes="surface">

    <xs:annotation>

      <xs:documentation>Sample Feature Class Description

      </xs:documentation>

      <xs:appinfo source="http://fdo.osgeo.org/schema" />

      <xs:documentation>Sample Geometric Property Description</xs:documentation>

    </xs:annotation>

    <xs:complexContent>

      <xs:extension base="gml:AbstractFeatureType">

        <xs:sequence>

          <xs:element name="SampleIdentityDataProperty"

            default=""

            type="fdo:int32">

            <xs:annotation>

              <xs:documentation>

                Sample Identity Data Property Description

              </xs:documentation>

            </xs:annotation>

          </xs:element>

          <xs:element name="SampleNameDataProperty"

            default="">

            <xs:annotation>

              <xs:documentation>

                Sample Name Data Property Description

              </xs:documentation>

            </xs:annotation>

            <xs:simpleType>

              <xs:restriction base="xs:string">

                <xs:maxLength value="64" />

              </xs:restriction>

            </xs:simpleType>

          </xs:element>

        </xs:sequence>

      </xs:extension>

    </xs:complexContent>

  </xs:complexType>

</xs:schema>

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