| Fix the following issue: |
|
|
| # Fix DataFrame uploads with reserved/geometry columns |
|
|
| Uploading a `pandas`/`geopandas` DataFrame to CARTO via `Dataset(df).upload(...)` is |
| generating inconsistent and sometimes broken SQL. For example, a DataFrame whose only |
| columns are `cartodb_id` and `the_geom` ends up producing a `CREATE TABLE` statement with |
| a dangling leading comma like `CREATE TABLE t (, the_geom geometry(...))`, which the |
| database rejects. The root cause is that the column list used to create the table, the |
| column list used in the `COPY` statement, and the values written to each row are all |
| computed independently and can disagree about how many columns there are and what they are |
| called. |
|
|
| Make the upload path derive a single, consistent description of the destination columns |
| from the DataFrame and use it everywhere. The observable behavior of an upload (the |
| `CREATE TABLE` statement and the `COPY ... FROM stdin` statement together with the rows of |
| CSV data streamed to the backend) must satisfy the following contract. |
|
|
| ## Column selection and ordering |
|
|
| - Every column of the DataFrame is uploaded, in the DataFrame's original column order. In |
| particular `cartodb_id` is treated as a normal column and is kept. |
| - A column named `the_geom_webmercator` (matched case-insensitively) is always dropped and |
| never appears in the table, the `COPY` column list, or the data. |
|
|
| ## Geometry handling |
|
|
| - Exactly one column is treated as the geometry. If the DataFrame is a GeoDataFrame with an |
| active geometry column, that column is used; otherwise the first column whose lower-cased |
| name is one of `the_geom`, `geom`, `geometry` is used, considered in that order of |
| priority (so if several are present, `the_geom` wins, then `geom`, then `geometry`). |
| - The chosen geometry column is named `the_geom` in the destination, declared with type |
| `geometry(<GeometryType>, 4326)` where `<GeometryType>` is detected from the data (e.g. |
| `Point`), and its values are emitted as `SRID=4326;<WKT>`. A null/missing geometry value |
| produces an empty field. |
| - Any other column that merely happens to be named like a geometry but was not selected as |
| *the* geometry column is uploaded as an ordinary column: it keeps its (normalized) name |
| and its value is written verbatim, not re-encoded. |
|
|
| ## Ordinary columns |
|
|
| - Non-geometry column names are normalized to SQL-safe names (lower-cased, spaces and other |
| unsupported characters replaced, etc.) in both the `CREATE TABLE` and the `COPY` column |
| list. Values are written in their string form; a null value produces an empty field. |
| - Column SQL types in `CREATE TABLE` are derived from the DataFrame dtypes: |
| `float64`/`float32` → `numeric`, `int64` → `bigint`, `int32` → `integer`, |
| `object` → `text`, `bool` → `boolean`, datetime dtypes → `timestamp`; anything else |
| defaults to `text`. |
|
|
| ## `with_lnglat` |
| |
| - When `with_lnglat=(lng_col, lat_col)` is passed, an extra geometry column named |
| `the_geom` of type `geometry(Point, 4326)` is appended after the regular columns, built |
| per row as `SRID=4326;POINT (<lng> <lat>)`. The `lng_col` and `lat_col` columns are still |
| uploaded as ordinary columns. |
| - When `with_lnglat` is used, any geometry column that would otherwise have been detected in |
| the DataFrame is dropped, so the synthesized point is the only geometry uploaded. |
|
|
| ## Statement format |
|
|
| The `COPY` statement keeps its existing shape: |
|
|
| ``` |
| COPY <table>(<col1>,<col2>,...) FROM stdin WITH (FORMAT csv, DELIMITER '|'); |
| ``` |
|
|
| with the destination column names joined by commas (no spaces). Each streamed row is the |
| column values joined by `|` and terminated by a newline, encoded to bytes. |
|
|
