<p t-foreach="[1, 2, 3]" t-as="i"> <t t-set="existing_variable" t-value="True"/> <t t-set="new_variable" t-value="True"/> <!-- existing_variable and new_variable now True --> </p>

<!-- existing_variable always True --> <!-- new_variable undefined --> attributes qPlate can compute attributes on-the-fly and set the result of the computation on the output node. This is done via the t-att (attribute) directive which exists in 4 different forms: $name="{{...}}" an attribute called $name is created, the attribute value contains in the braces is evaluated and the result is set as the attribute's value: <div class="static {{'add-class'}}"/> will be rendered as: <div class="static add-class"></div> t-att-$name an attribute called $name is created, the attribute value is evaluated and the result is set as the attribute's value: <div t-att-a="42"/> will be rendered as: <div a="42"></div> t-attf-$name same as previous, but the parameter is a format string instead of just an expression, often useful to mix literal and non-literal string (e.g. classes): <t t-foreach="[1, 2, 3]" t-as="item"> <li t-attf-class="row {{ item_parity }}"><t t-esc="item"/></li> </t> will be rendered as: <li class="row even">1</li> <li class="row odd">2</li> <li class="row even">3</li> t-att=mapping if the parameter is a mapping, each (key, value) pair generates a new attribute and its value: <div t-att="{'a': 1, 'b': 2}"/> will be rendered as: <div a="1" b="2"></div> t-att=pair if the parameter is a pair (tuple or array of 2 element), the first item of the pair is the name of the attribute and the second item is the value: <div t-att="['a', 'b']"/> will be rendered as: <div a="b"></div> setting variables qPlate allows creating variables from within the template, to memoize a computation (to use it multiple times), give a piece of data a clearer name, ... This is done via the set directive, which takes the name of the variable to create. The value to set can be provided in two ways: a t-value attribute containing an expression, and the result of its evaluation will be set: <t t-set="foo" t-value="2 + 1"/> <t t-esc="foo"/> will print 3 if there is no t-value attribute, the node's body is rendered and set as the variable's value: <t t-set="foo"> <li>ok</li> </t> <t t-esc="foo"/> will generate &lt;li&gt;ok&lt;/li&gt; (the content is escaped as we used the esc directive) Note using the result of this operation is a significant use-case for the raw directive. calling sub-templates qPlate templates can be used for top-level rendering, but they can also be used from within another template (to avoid duplication or give names to parts of templates) using the t-call directive: <t t-call="other-template"/> This calls the named template with the execution context of the parent, if other_template is defined as: <p><t t-value="var"/></p> the call above will be rendered as <p/> (no content), but: <t t-set="var" t-value="1"/> <t t-call="other-template"/> will be rendered as <p>1</p>. However this has the problem of being visible from outside the t-call. Alternatively, content set in the body of the call directive will be evaluated before calling the sub-template, and can alter a local context: <t t-call="other-template"> <t t-set="var" t-value="1"/> </t> <!-- "var" does not exist here --> The body of the call directive can be arbitrarily complex (not just set directives), and its rendered form will be available within the called template as a magical 0 variable: <div> This template was called with content: <t t-raw="0"/> </div> being called thus: <t t-call="other-template"> <em>content</em> </t> will result in: <div> This template was called with content: <em>content</em> </div> template inheritance Template inheritance is used to alter existing templates in-place, e.g. to add information to templates created by an other modules. Template inheritance is performed via the t-extend directive which takes the name of the template to alter as parameter. The alteration is then performed with any number of t-xpath sub-directives: <t t-extend="base.template"> <t t-xpath="//ul" t-operation="append"> <li>new element</li> </t> <t t-xpath="//ul/li/@name" t-operation="replace"> <li>attribute value</li> </t> </t> The t-xpath directives takes a Xpath selector. This selector is used on the extended template to select context nodes to which the specified t-operation is applied: append the node's body is appended at the end of the context node (after the context node's last child) prepend the node's body is prepended to the context node (inserted before the context node's first child) replace the node's body is used to replace the context node itself before the node's body is inserted right before the context node (not available when target an attribute) after the node's body is inserted right after the context node (not available when target an attribute) inner the node's body replaces the context node's children (not available when target an attribute) No operation if no t-operation is specified, the template body is interpreted as javascript code and executed with the context node as this Warning while much more powerful than other operations, this mode is also much harder to debug and maintain, it is recommended to avoid it debugging The javascript qPlate implementation provides a few debugging hooks: t-log takes an expression parameter, evaluates the expression during rendering and logs its result with console.log: <t t-set="foo" t-value="42"/> <t t-log="foo"/> will print 42 to the console t-debug triggers a debugger breakpoint during template rendering: <t t-if="a_test"> <t t-debug=""> </t> will stop execution if debugging is active (exact condition depend on the browser and its development tools) t-js the node's body is javascript code executed during template rendering. Takes a context parameter, which is the name under which the rendering context will be available in the t-js's body: <t t-set="foo" t-value="42"/> <t t-js="ctx"> console.log("Foo is", ctx.foo); </t> XPath See also http://jean-luc.massat.perso.luminy.univ-amu.fr/ens/xml/04-xpath.html Expression Refers to ./author All <author> elements within the current context. Note that this is equivalent to the expression in the next row. author All <author> elements within the current context. first.name All <first.name> elements within the current context. /bookstore The document element (<bookstore>) of this document. //author All <author> elements in the document. book[/bookstore/@specialty=@style] All <book> elements whose style attribute value is equal to the specialty attribute value of the <bookstore> element at the root of the document. author/first-name All <first-name> elements that are children of an <author> element. bookstore//title All <title> elements one or more levels deep in the <bookstore> element (arbitrary descendants). Note that this is different from the expression in the next row. bookstore/*/title All <title> elements that are grandchildren of <bookstore> elements. bookstore//book/excerpt//emph All <emph> elements anywhere inside <excerpt> children of <book> elements, anywhere inside the <bookstore> element. .//title All <title> elements one or more levels deep in the current context. Note that this situation is essentially the only one in which the period notation is required. author/* All elements that are the children of <author> elements. book/*/last-name All <last-name> elements that are grandchildren of <book> elements. */* All grandchildren elements of the current context. *[@specialty] All elements with the specialty attribute. @style The style attribute of the current context. price/@exchange The exchange attribute on <price> elements within the current context. price/@exchange/total Returns an empty node set, because attributes do not contain element children. This expression is allowed by the XML Path Language (XPath) grammar, but is not strictly valid. book[@style] All <book> elements with style attributes, of the current context. book/@style The style attribute for all <book> elements of the current context. @* All attributes of the current element context. ./first-name All <first-name> elements in the current context node. Note that this is equivalent to the expression in the next row. first-name All <first-name> elements in the current context node. author[1] The first <author> element in the current context node. author[first-name][3] The third <author> element that has a <first-name> child. my:book The <book> element from the my namespace. my:* All elements from the my namespace. @my:* All attributes from the my namespace (this does not include unqualified attributes on elements from the my namespace). ------------ x/y[1] The first <y> child of each <x>. This is equivalent to the expression in the next row. x/y[position() = 1] The first <y> child of each <x>. (x/y)[1] The first <y> from the entire set of <y> children of <x> elements. x[1]/y[2] The second <y> child of the first <x>. ------------ book[last()] The last <book> element of the current context node. book/author[last()] The last <author> child of each <book> element of the current context node. (book/author)[last()] The last <author> element from the entire set of <author> children of <book> elements of the current context node. book[excerpt] All <book> elements that contain at least one <excerpt> element child. book[excerpt]/title All <title> elements that are children of <book> elements that also contain at least one <excerpt> element child. book[excerpt]/author[degree] All <author> elements that contain at least one <degree> element child, and that are children of <book> elements that also contain at least one <excerpt> element. book[author/degree] All <book> elements that contain <author> children that in turn contain at least one <degree> child. author[degree][award] All <author> elements that contain at least one <degree> element child and at least one <award> element child. author[degree and award] All <author> elements that contain at least one <degree> element child and at least one <award> element child. author[(degree or award) and publication] All <author> elements that contain at least one <degree> or <award> and at least one <publication> as the children author[degree and not(publication)] All <author> elements that contain at least one <degree> element child and that contain no <publication> element children. author[not(degree or award) and publication] All <author> elements that contain at least one <publication> element child and contain neither <degree> nor <award> element children. author[last-name = "Bob"] All <author> elements that contain at least one <last-name> element child with the value Bob. author[last-name[1] = "Bob"] All <author> elements where the first <last-name> child element has the value Bob. Note that this is equivalent to the expression in the next row. author[last-name [position()=1]= "Bob"] All <author> elements where the first <last-name> child element has the value Bob. degree[@from != "Harvard"] All <degree> elements where the from attribute is not equal to "Harvard". degree[@from %= "Har%"] All <degree> elements where the from attribute begin by "Har". degree[@from *= "arva"] All <degree> elements where the from attribute contains "arva". degree[@from ?= "[Aar]+.a"] All <degree> elements where the from attribute match as regular expression "[Aar]+.a". author[. = "Matthew Bob"] All <author> elements whose value is Matthew Bob. author[last-name = "Bob" and ../price &gt; 50] All <author> elements that contain a <last-name> child element whose value is Bob, and a <price> sibling element whose value is greater than 50. book[position() &lt;= 3] The first three books (1, 2, 3). author[not(last-name = "Bob")] All <author> elements that do no contain <last-name> child elements with the value Bob. author[first-name = "Bob"] All <author> elements that have at least one <first-name> child with the value Bob. author[* = "Bob"] all author elements containing any child element whose value is Bob. author[last-name = "Bob" and first-name = "Joe"] All <author> elements that has a <last-name> child element with the value Bob and a <first-name> child element with the value Joe. price[@intl = "Canada"] All <price> elements in the context node which have an intl attribute equal to "Canada". degree[position() &lt; 3] The first two <degree> elements that are children of the context node. p/text()[2] The second text node in each <p> element in the context node. ancestor::book[1] The nearest <book> ancestor of the context node. ancestor::book[author][1] The nearest <book> ancestor of the context node and this <book> element has an <author> element as its child. ancestor::author[parent::book][1] The nearest <author> ancestor in the current context and this <author> element is a child of a <book> element.