Allors.Documents.Reflection 3.1.0

Allors Documents

Embed template tags inside OpenDocument texts: write the template in LibreOffice Writer, bind it to a model, render the document.

Status

Packages

Usage

using Allors.Document.OpenDocument;
using Allors.Document.Reflection;
using Allors.Document.Validation;

var template = new OpenDocumentTemplate<InvoiceModel>(templateBytes);
RenderResult result = template.Render(model);

File.WriteAllBytes("invoice.odt", result.Document);
foreach (Finding finding in result.Findings)
{
    Console.WriteLine(finding); // error: <$Invoice.Totl>: Invoice has no member Totl (content.xml paragraph 12 "Total <$Invoice.Totl>")
}

A template over a model type sees the public properties of T by their exact names and reads what is below them through reflection. The non-generic OpenDocumentTemplate takes any model and reads it as a dictionary unless the settings name another resolver:

var template = new OpenDocumentTemplate(templateBytes);
var model = new Dictionary<string, object> { ["Invoice"] = invoice, ["Issuer"] = issuer };
var settings = new RenderSettings { Resolver = ReflectionResolver.Instance, Culture = new CultureInfo("nl-BE"), DateCulture = CultureInfo.InvariantCulture, Number = "N2", Date = "dd-MMM-yyyy" };
RenderResult result = template.Render(model, settings);

A template is read once and rendered any number of times, from any thread. It may be a package (.odt) or a flat document (.fodt), and it renders a package unless the settings ask for a flat document. Reading a template throws InvalidDataException when the bytes are not an OpenDocument text, and TemplateException when a block never ends, an end opens nothing or a block would cut a table; Findings says which tags and where. A render never throws for what the template says: a value the model cannot give prints blank, and Findings reports it.

Tags

Tags go into placeholder fields (Insert, Field, More Fields, Functions, Placeholder):

A path is a chain of member names separated by dots, such as Invoice.Customer.Name; inside a loop it may start with the variable of that loop or of an enclosing one. A name is letters, digits and underscores. Keywords and attribute names are not case-sensitive. A placeholder whose text is not a well-formed tag, such as <$> or <@for x>, renders as the text the author typed and is reported.

Attributes

A tag takes attributes after its path, with values quoted by " or ':

An attribute a tag of that kind does not know is a validation error.

Document settings

A template carries its own defaults as custom document properties (File, Properties, Custom Properties): culture, number-culture, date-culture, date, time, datetime, number, true and false. RenderSettings carries the same settings for the caller. Formatting layers from the library's defaults (the invariant culture, no patterns, the words true and false) up through the caller's settings, the template's properties and the tag's attributes; the last layer wins, so a template whose number property says #,##0.00 prints its numbers that way whatever the caller passed.

A culture is a .NET name such as nl-BE or en-GB, or invariant for the invariant culture, whose month names and separators are the same on every machine. number-culture and date-culture set one kind apart from culture: numbers print in number-culture, dates, times and date-times in date-culture, and the rest follows culture, sorting included; a kind without a culture of its own follows culture too. The layers combine the cultures as style sheets do: a layer that sets culture resets the cultures per kind of the layers below it, and within one layer a culture per kind wins over culture, whatever the order of the properties. So a caller that prints 1.250,50 and 14-Sep-2026 with Culture = nl-BE and DateCulture = invariant is overridden as a whole by a template whose culture says en-GB, while a template whose date-culture says nl-BE changes only the dates. A tag's culture prints that one value in that culture whatever its kind, and is the only culture attribute a tag takes.

Values

• Null prints blank; text prints as it is.
• A boolean prints the true or false word.
• A date prints with the date pattern when it has no time of day and with the datetime pattern otherwise; on .NET, a DateOnly prints with date and a TimeOnly with time.
• A number prints with the number pattern; any other formattable value, such as a TimeSpan or a Guid, prints with the tag's format.
• An enum prints its name. A collection bound as a value prints its items one after the other, formatted, with nothing between them; a loop is what separates them.
• Everything else prints through ToString().

Patterns are .NET format strings, applied in the culture of the value's kind: number-culture for a number, date-culture for a date or a time, and culture unless they say otherwise.

Loops

A loop visits what the resolver yields for the value at its path: nothing for null, text once, the keys of a dictionary, the items of any other enumerable with null items skipped, and any other value once. sort orders the items before the loop runs and before the counter counts; items whose keys cannot be ordered against each other keep the collection's order, which is reported as CannotSort.

Paths that break

A member the model does not have prints blank, keeps a condition false and loops over nothing; it is reported once per tag as UnknownMember. A null before the end of a path prints blank in silence: <$Invoice.Customer.Name> prints nothing when the invoice has no customer. <@ifdef> on a path that is null before its end is false, without a finding.

Pictures

A picture binds through its description (Image, Properties, Options, Description), which holds exactly one picture tag:

<$Issuer.Logo>
<$item.Photo fit="contain" empty="keep">

The frame shows the picture at that path: the bytes the resolver yields for the value, in a format the bytes tell, PNG, JPEG, GIF, WebP, BMP, TIFF, SVG, EMF or WMF. The frame's name stays the author's and its alternative text stays in the output; the description that held the tag leaves it.

The proportions come from the picture's header. Bytes that do not tell their size, and a frame without a width and a height, fill and report CannotFit.

A picture is stored once per distinct content, under Pictures/<path>.<ext>, with .2, .3 for further pictures at the same path: Pictures/Issuer.Logo.png, Pictures/item.Photo.jpg, Pictures/item.Photo.2.jpg. Template pictures that no frame shows any more leave the package and its manifest. Every frame's name is made unique in the document (Photo, Photo 2), as Writer requires, so a bound frame may sit in a loop.

Rendering rules

• The template renders as typed. Static text and attribute values pass unchanged, including &, < and >. The engine adds no white space of its own: a word split by formatting stays one word, and two adjacent tags render without a space between them.
• Bound values are escaped for XML and keep their white space: a tab becomes text:tab, a line break text:line-break and a run of spaces text:s, as Writer saves them. Other characters below U+0020 are dropped.
• The paragraph or table row that holds a <@for>, <@if>, <@ifdef> or <@end> tag is removed with the rest of its text, so give each tag its own paragraph or row. When both tags of a block sit in one paragraph only the tags themselves are removed, so a short condition or loop can stay inline. The begin and the end of a block sit in paragraphs of one container or in rows of one table; a block that would cut a table throws when the template is read.
• The body and the headers and footers render against the same model; a loop variable is in scope between its tags only.
• The output reads as the template did: the XML declaration, no byte order mark, a full end tag on every element of the template, comments and processing instructions kept.
• The package starts with an uncompressed mimetype entry. PNG, JPEG, GIF and WebP pictures are stored; everything else is deflated.

Flat documents

A template may be a flat OpenDocument text (.fodt, File, Save As, Flat XML ODF Text Document): one XML file with the pictures embedded. RenderSettings.Flat = true renders one, pictures embedded as base64; the default is a package, whatever the template's form. The findings of a flat template name content.xml for the body and styles.xml for the styles with the headers and footers, the parts the engine splits it into. Embedded objects such as charts and formulas are not converted between the two forms.

Inspect

Inspect reads a template without a model and lists what it asks for: every tag in document order with its part and paragraph, the bound picture frames, the document settings, and the tags it cannot read.

TemplateInspection inspection = OpenDocumentTemplate.Inspect(templateBytes);

inspection.Paths;      // every distinct path, bindings and pictures alike
inspection.Bindings;   // the <$path> tags, each with Tag, Location and the enclosing Block
inspection.Blocks;     // the for, if and ifdef tags, each with its Children and End
inspection.Pictures;   // the frames whose description is a picture tag, each with FrameName, Tag and Location
inspection.Settings;   // the custom document properties
inspection.Problems;   // malformed tags and unbalanced blocks

A Location names the part (content.xml or styles.xml), the paragraph's ordinal and its text.

Validate

Validate checks a template against the shape of its model, without rendering and without data: every path, attribute, block and document setting. It never throws for what the template says; it throws only when the bytes are not an OpenDocument text.

using Allors.Document.Reflection;

IShape model = ReflectionShape.Arguments<InvoiceModel>();
TemplateValidation validation = OpenDocumentTemplate.Validate(templateBytes, model);

if (!validation.IsValid)
{
    foreach (Finding finding in validation.Errors)
    {
        Console.WriteLine(finding); // error: <$Invoice.Totl>: Invoice has no member Totl (content.xml paragraph 12 "Total <$Invoice.Totl>")
    }
}

The shape is the root the template renders against. ReflectionShape.Arguments<T>() is what OpenDocumentTemplate<T> sees: the public properties of T by their exact names. ReflectionShape.Of<T>() is an object of T itself, for a model rendered through ReflectionResolver. For a dictionary model use DictionaryShape: DictionaryShape.Open accepts every member, new DictionaryShape(members) knows exactly which names exist and what their shapes are. IsValid is true when there are no errors. Inside an <@if> or <@ifdef> block the guarded path is narrowed to the shapes that have the member, for models whose shapes declare Variants.

Findings

A Finding says what is wrong in the author's terms: the kind, the severity, the tag as typed, the path, a message and the Location. Validate reports everything it can tell from the template and the shape; Render reports what depends on the data; the constructor throws TemplateException with the findings a template cannot render with.

Models

Two interfaces describe a model. IShape is the static view Validate walks: the members a value has, whether it is a collection, the shape of its items, and the variants of an abstract shape. IResolver is the runtime view the renderer reads through: TryGetMember, Items, IsTrue, Format, Compare and Picture. The Resolver base class carries the rules this document describes for iteration, truthiness, formatting and ordering, and takes a byte array as a picture; derive from it, implement TryGetMember, and override the rest for your own value types. A resolver may hand out its own value types and recognise them again when it formats, compares or iterates them, which is how a host prints an amount in its currency.

TryGetMember returns false for a member the scope does not have, which the renderer reports, and true with a null value for a member that is empty, which prints blank. The renderer never passes a null scope.

Build

Prerequisites: .NET SDK 10.0 and Task.

• task or task ci — build, test and pack
• task test — build and run tests
• task pack — create the NuGet packages in artifacts/nuget
• task clean — clean build outputs

Versioning is handled by Nerdbank.GitVersioning (version.json).

Release

Pushing a tag vX.Y.Z or vX.Y.Z-rc.N runs release.yml: it builds, tests and packs, publishes both packages to nuget.org through trusted publishing from the nuget-release environment, and creates a GitHub release. The package version comes from version.json, so set it to the tag's version before tagging.