Protobufquery is an XPath query package for ProtocolBuffer documents. It lets you extract data from parsed ProtocolBuffer message through an XPath expression. Built-in XPath expression cache avoid re-compilation of XPath expression for each query.
go get github.com/doclambda/protobufquery
msg := addressbookSample.ProtoReflect()
doc, err := Parse(msg)ProtocolBuffer messages can also be instantiated dynamically using the dynamicpb package. Check out the referenced documentation for examples on loading bytes into those instances.
Using the ProtocolBuffer definition in testcases/addressbook we can define an example addressbook as
addressbook.AddressBook{
People: []*addressbook.Person {
{
Name: "John Doe",
Id: 101,
Email: "[email protected]",
Age: 42,
},
{
Name: "Jane Doe",
Id: 102,
Age: 40,
},
{
Name: "Jack Doe",
Id: 201,
Email: "[email protected]",
Age: 12,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-555-5555", Type: addressbook.Person_WORK},
},
},
{
Name: "Jack Buck",
Id: 301,
Email: "[email protected]",
Age: 19,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-555-0000", Type: addressbook.Person_HOME},
{Number: "555-555-0001", Type: addressbook.Person_MOBILE},
{Number: "555-555-0002", Type: addressbook.Person_WORK},
},
},
{
Name: "Janet Doe",
Id: 1001,
Email: "[email protected]",
Age: 16,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-777-0000"},
{Number: "555-777-0001", Type: addressbook.Person_HOME},
},
},
},
Tags: []string {"home", "private", "friends"},
}Using this definition we can perform the example queries below.
xml := doc.OutputXML()list := protobufquery.Find(doc, "/descendant::*[name() = 'people']/name")
// or equal to
list := protobufquery.Find(doc, "//name")
// or by QueryAll()
nodes, err := protobufquery.QueryAll(doc, "//name")list := protobufquery.Find(doc, "/people[3]")book := protobufquery.Find(doc, "//phones[1]/number")book := protobufquery.Find(doc, "//phones[last()]/number")list := protobufquery.Find(doc, "/people[not(email)]")list := protobufquery.Find(doc, "/people[age > 18]")func main() {
addressbookSample := &addressbook.AddressBook{
People: []*addressbook.Person {
{
Name: "John Doe",
Id: 101,
Email: "[email protected]",
Age: 42,
},
{
Name: "Jane Doe",
Id: 102,
Age: 40,
},
{
Name: "Jack Doe",
Id: 201,
Email: "[email protected]",
Age: 12,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-555-5555", Type: addressbook.Person_WORK},
},
},
{
Name: "Jack Buck",
Id: 301,
Email: "[email protected]",
Age: 19,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-555-0000", Type: addressbook.Person_HOME},
{Number: "555-555-0001", Type: addressbook.Person_MOBILE},
{Number: "555-555-0002", Type: addressbook.Person_WORK},
},
},
{
Name: "Janet Doe",
Id: 1001,
Email: "[email protected]",
Age: 16,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-777-0000"},
{Number: "555-777-0001", Type: addressbook.Person_HOME},
},
},
},
Tags: []string {"home", "private", "friends"},
}
doc, err := protobufquery.Parse(addressbookSample.ProtoReflect())
if err != nil {
panic(err)
}
nodes, err := protobufquery.QueryAll(doc, "//people")
if err != nil {
panic(err)
}
for _, person := range nodes {
name := protobufquery.FindOne(person, "name").InnerText()
numbers := make([]string, 0)
for _, node := range protobufquery.Find(person, "phones/number") {
numbers = append(numbers, node.InnerText())
}
fmt.Printf("%s: %s", name, strings.Join(numbers, ","))
}
}If you are familiar with XPath and XML, you can easily figure out how to write your XPath expression.
addressbook.AddressBook{
People: []*addressbook.Person {
{
Name: "John Doe",
Id: 101,
Email: "[email protected]",
Age: 42,
},
{
Name: "Jane Doe",
Id: 102,
Age: 40,
},
{
Name: "Jack Doe",
Id: 201,
Email: "[email protected]",
Age: 12,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-555-5555", Type: addressbook.Person_WORK},
},
},
{
Name: "Jack Buck",
Id: 301,
Email: "[email protected]",
Age: 19,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-555-0000", Type: addressbook.Person_HOME},
{Number: "555-555-0001", Type: addressbook.Person_MOBILE},
{Number: "555-555-0002", Type: addressbook.Person_WORK},
},
},
{
Name: "Janet Doe",
Id: 1001,
Email: "[email protected]",
Age: 16,
Phones: []*addressbook.Person_PhoneNumber{
{Number: "555-777-0000"},
{Number: "555-777-0001", Type: addressbook.Person_HOME},
},
},
},
Tags: []string {"home", "private", "friends"},
}The above ProtocolBuffer representation above will be convert by protobufquery to a structure similar to the XML document below:
<?xml version="1.0" encoding="UTF-8"?>
<people>
<name>John Doe</name>
<id>101</id>
<email>[email protected]</email>
<age>42</age>
</people>
<people>
<name>Jane Doe</name>
<id>102</id>
<age>40</age>
</people>
<people>
<name>Jack Doe</name>
<id>201</id>
<email>[email protected]</email>
<age>12</age>
<phones>
<number>555-555-5555</number>
<type>2</type>
</phones>
</people>
<people>
<name>Jack Buck</name>
<id>301</id>
<email>[email protected]</email>
<age>19</age>
<phones>
<number>555-555-0000</number>
<type>1</type>
</phones>
<phones>
<number>555-555-0001</number>
</phones>
<phones>
<number>555-555-0002</number>
<type>2</type>
</phones>
</people>
<people>
<name>Janet Doe</name>
<id>1001</id>
<email>[email protected]</email>
<age>16</age>
<phones>
<number>555-777-0000</number>
</phones>
<phones>
<number>555-777-0001</number>
<type>1</type>
</phones>
</people>
<tags>
<element>home</element>
<element>private</element>
<element>friends</element>
</tags>Note: element is an anonymous element without name.
| Name | Description |
|---|---|
| htmlquery | XPath query package for the HTML document |
| xmlquery | XPath query package for the XML document |
| jsonquery | XPath query package for the JSON document |
| protobufquery | XPath query package for ProtocolBuffer messages |