GIS - TryCreateForInput

Dear Michael,

Thank you very much for your help and the code.

I implemented only these converters: Shapefile, Csv, Gml, so all checks not ready.

Before I will your tests:

1.GeoJson -this what you wrote:

FormatDescriptor("GeoJson", new[] { ".geojson" }, new[] { ".geojson" }) },

GeoJson has .json also is handled separately? how to fix it?

2.EsriJson -this what you wrote:

{ "EsriJson", new FormatDescriptor("EsriJson", new[] { ".esrijson" }, new[] { ".esrijson" }) },

GeoJson has .json also is handled separately? how to fix it?

3.GeoJsonSeq -this what you wrote:

{ "GeoJsonSeq", new FormatDescriptor("GeoJsonSeq", new[] { ".jsonl", ".ndjson" }, Array.Empty<string>()) },

GeoJsonSeq has .json format only , how to fix it?

Does it support also :".jsonl", ".ndjson" ?

4.TopoJson - this what you wrote:

{ "TopoJson", new FormatDescriptor("TopoJson", new[] { ".topojson" }, Array.Empty<string>()) },

TopoJson has .json format only , how to fix it?

Does it support also :".topojson" ?

4.Shapefile- this what you wrote:

{ "Shapefile", new FormatDescriptor("Shapefile", new[] { ".shp" }, new[] { ".shp", ".shx", ".dbf" }) },

In case of single file .shp, is the converter responsibility to say there are missing mandatories files:".shp", ".shx", ".dbf" , id no how to fix it?

5. Gdb- Gdb file can be represent as a dataset or just as one table. In case of dataset - the entire .gdb folder as a single file In case of one table - .gdbtable and .gdbtablx as an archive file. Does in case of one table the extension also .gdb if not your code not handle it? Can you please how to fix it?

If your fixes need a lot of changes, please provide a new modified file.

Thanks in advance,

Your quick answer will be appreciated.

I will address each item:

1–3. GeoJSON, EsriJSON, GeoJSONSeq, and TopoJSON with .json extension

When a file has the generic .json extension, the code intentionally skips the extension map and falls through to content‑based detection:

// fast-path: explicit non-json extensions
var explicitFormat = Formats.Values.FirstOrDefault(f =>
    f.MatchesFileExtension(ext) && !ext.Contains("json"));  // ← skips json variants

if (explicitFormat != null)
{
    detectReason = $"extension '{ext}' mapped to {explicitFormat.Name}";
    return factory.TryCreate(explicitFormat.Name, out converter);
}

// json variants require content inspection
if (ext.EndsWith("json", StringComparison.OrdinalIgnoreCase))
{
    var jsonFormat = DetectJsonFormat(filePath, out var jsonReason);  // ← content-based detection
    // ...
}

The current code already handles .json files correctly by reading the content and classifying them. You do not need to add .json to the file extensions in the descriptor.

Does it support also :".jsonl", ".ndjson" ?

For GeoJSONSeq, it supports .jsonl and .ndjson extensions—those are already in the descriptor for fast‑path matching. Files with the plain .json extension will be detected via the NDJSON heuristic in LooksLikeNdjson.

Does it support also :".topojson" ?

For TopoJSON, the .topojson extension is supported for fast‑path matching, but most TopoJSON files use .json and will be detected via content inspection (looking for "type": "Topology").

No changes are needed for items 1–3. The code is already designed this way.

4. Shapefile missing mandatory files

In case of single file .shp, is the converter responsibility to say there are missing mandatories files:".shp", ".shx", ".dbf" , id no how to fix it?

Validation is not the responsibility of the format detection code.

The detector’s job is to answer: “What converter should I use for this input?” If someone provides a single .shp file, the detector correctly identifies it as Shapefile format and returns the Shapefile converter.

The converter itself should validate that all required files are present when it tries to open the Shapefile, and return a meaningful error such as “Missing required .shx file” if they are not.

No changes are needed for Shapefile detection.

5. GDB single‑table format

Gdb file can be represent as a dataset or just as one table. In case of dataset - the entire .gdb folder as a single file In case of one table - .gdbtable and .gdbtablx as an archive file. Does in case of one table the extension also .gdb if not your code not handle it? Can you please how to fix it?

The current code only detects the folder‑based .gdb extension. To support single‑table mode, you need to add the table extensions to the descriptor:

{ "Gdb", new FormatDescriptor("Gdb", new[] { ".gdb", ".gdbtable" }, new[] { ".gdb", ".gdbtable", ".gdbtablx" }) },

However, there is a complication: single‑table mode requires both .gdbtable and .gdbtablx files to be valid (similar to Shapefile). But in single‑file mode, you might only provide one of them.

To handle it:

• For single‑file input (just .gdbtable): the detector will match it to GDB format, and the converter should validate that the corresponding .gdbtablx exists in the same directory.
• For archive input: the archive requirements check will ensure both .gdbtable and .gdbtablx are present before selecting GDB format.